Pnblication1 Committee: F. w. GRAFF R. H. GRIFFITH G. C. BUTTE < J. ·L. HENDERSON D. B. CASTEEL E. J. MATTHEWS FREDERIC DUNCALF C. E.RoWE ' , --t ~ The Univ~rsity publishes bull~tins six times a month, so ·nUm.­.bered that the first two digits of the number show the year of issue; -the last two the position in !he_ yearly series. (For ex­ample, Ne. 1701 is the first bulletin .of the year 1917.) These • . comprise the official publications of the "University, publications on humanistie and scientific subjects, bulletins prepared by the . Department_of Extension and by the Bureau of Government Re­search, and other bulletins of general educationaI interest. With . the exception of special n:um'Qers, any b.uJ.letin will. be sent to a citizen of Texas free on request: All communications about Uni­versity plibllcatjons should be. addressed to the Chairman of the Publications Committee, University of ~ex:as, Aus~in. Bl2'6-lllfHM-L University of Texas Bulletin No. 1932: June 5, 1919 The Geology and Mineral Resources of Bexar County By E. H. SELLARDS BUREAU OP ECONOMIC GEOLOGY AND TECXNOLOG~ DIVISION OF ECONOMIC GEOLOGY J. A. UDDEN, Director of the Bureau and Read of the Division PUBLISHED BY THE UNIVERSITY SIX TIMES A MONTH, AND ENTERED AS SECOND-CLASS MATTER AT THE POSTOFFICE AT AUSTIN, TEXAS, UNDER THE ACT OF AUGUST 2i, 1912 The benefits of education and of useful knowledge, generally diJfused through a coDIDWJlity, are essential to the preservation of a free govern­ment. Sam Houston Oo.Itivated mind is the guardian genius of democracy. • • It is the only dictator that freemen acknowl­edge and the only security that free­men desire. Mirabeau B. Lamar CONTENTS Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Early settlements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Acknowledginents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Location with respect to major physiographic divisions. . . . . 10 Topography and drainage . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . 12 Climate and rainfall . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Balcones Escarpment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • 13 Minor physiographic divisions ........................... 14 The Glenrose hills . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 The Edwards flint hills . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 The Del Rio plain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 The Austin hills . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 The Taylor-Navarro plain ........................... 17 The Midway-Wilcox hills ........................•.. 18 The Carrizo sand hills . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Stream terrace plains , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Stratigraphic geology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 The Pre-Cretaceous sediments . . . . . . . . . . . . . . . . . . . . . . . . . 19 Table of geologic formations . . . . . . . . . . . . . . . . . . . . . . . . . . 20 The Mesozoic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Comanchean Cretaceous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Trinity Travis Peak formation . . . . . . . . . . . . . . . . . . . . . . . . . 21 Glenrose formation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Fredericksburg Comanche Peak formation . . . . . . . . . . . . . . . . . . . . . 24 Edwards formation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 Washita Georgetown formation . . . . . . . . . . . . . . . . . . . . . . . . . . 27 Del Rio formation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 Buda formation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 Upper Cretaceous .................................... 34 Eagle Ford formation . . . . . . . . . . . . . . . . . . . . . . . . . . 34 Austin formation .............................. 36 Tayior formation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 Navarro formation ............................. 49 The Cretaceous-Tertiary contact . . . . . . . . . . . . . . . . . . . . . . . 53 The Cenozoic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 Eocene ....................................... 54 Midway formation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 Wilcox formation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 Carrizo formation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 Pleistocene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 Uvalde formation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 Leona formation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 CONTENTS Late Pleistocene Alluvial deposits ................. 72 Cave deposits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73 Recent ................. . ............................ 74 Calcareous concretions .. . ....... . .................... 75 Structural geology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . 77 Location of principal faults ..................... 77 Structurally high areas . . . . . . . . . . . . . . . . . . . . . . . . 82 The Culebra structure . . . . . . . . . . . . . . . . . . . . . . . . . . 83 The San Antonio structure . . . . . . . . . . . . . . . . . . . . . 84 The Alta Vista structure . . . . . . . . . . . . . . . . . . . . . . . 85 The Geological Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86 Index to levels on the Del Rio formation. . . . . . . . . . 87 Notes on exposures seen on the public roads, including Blanco, Bulverde, Nacogdoehes, Austin, St. Hedwig, Pleasanton, Somerset, PearsaJl, Castroville, Potranca Culebra, Bandera, Babcock and Fredericksburg roads ......................................... 90 Economic Geology ... , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 Artesian and other underground waters ................ 97 Principles of artesian wells and ground-water ac­cumulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98 Water of the Glenrose-Travis Peak formations .........100 Water of the Georgetown-Edwards limestones ...... . . 101 Areas of artesian flow ............................. 101 Water of the Del Rio and Buda formations .......... 103 Water of the Eagleford and Austin formations.......104 Water of the Taylor and Navarro formations ... . ......104 Water of the Tertiary formations....................104 Springs ................................... . ......104 Warm sulphur water in the Comanchean limestones ....105 Source of hydrogen sulphide in underground waters...106 Cement ............... ..................... ...... . . !08 Clay ....... . ....... . ....... . .......................112 Building brick ......................................112 Fuller's earth .... ...................................114 Bentonite .... ..................... .................115 Concrete ... ...... ..... .............................116 Greensand ..... .............. .................. .....117 Lignite .............................................118 Limestone ..................... . ........... .. ... . ...llB Lime ........ .. ........................ . ............120 Building st-0ne ... . . . ......................... . ......121 Petroleum and Natural gas............................121 The Alta Vista oil field ........ . ........ . .....122 The Mission oil field ...........................123 The Gas Ridge oil and gas field ........... .......123 The Somerset oil field .... . .....................124 CONTENTS The South Medina oil field .....................125 Relation of the Bexar County oil fields to structure......125 Quality of the Bexar County oil. . . . . . . . . . . . . . . . .......127 General considerations .. . ....................... . ....127 Road materials ......... . ....... .. ...................128 Well records ................................. . . . ......129 Wells entering the Pre-Cretaceous formations ... ........129 Wells terminating in the Comanchean formations . .......135 Tabulated records .......... .. . . ........ .. .....136 Logs and other data supplementary to the tab­ ulated records ........................143 Wells terminating in the Upper Cretaceous.. ..... ......171 Index ..............................................199 ILLUSTRATIONS. Figures. Page Fig. 1. Sketch niap to show the location of Bexar County with respect to the major physiographic provinces of Texas .... . ...... ... . ... ........... ... . ... .. 11 Fig. 2. Sketch map to show the minor physiographic prov­ inces in Bexar County . . . . . . . . . . . . . . . . . . . . . . . . 15 Fig. 3. Table of geologic formations and columnar section . . 20 Fig. 4. Graphic representation of logs of wells arranged in order from northwest to southeast. . . . . . . . . . . . 78 Fig 5. Schematic representation of structure on an approx­imately north-south line through Bexar County. . . . 79 Fig 6. Sketch map indicating the location of brick, cement and fullers earth plants, lime kilns, lignite mine, oil and gas fields, and areas of flowing artesian water ..... .................................... 98 Plate. Pl. 1. Pisolitic gravel in the Pleistocene as seen in pit ex­cavated for gravel road material near the Mission Loop Road south of San Antonio . . . . . . . . . . . . . . . . 72 Map. Geologic and structural map of Bexat' County .. Inside back cover GEOLOGY AND MlN.l!:RAL RESOURCES OE' BEXAR COUNTY• BY E. H. SELLARDS Bexar County is located in south-central Texas, about 125 miles from the Gulf Coast, and approximately an equal distance from the Mexican border. The adjoining counties are Kendall and Comal on the north, Guadalupe and Wilson on the east, Atascosa on the south, and Medina and Bandera on the west. San Antonio, the county-seat, is one of the large cities of the southwest part of the United States. The area of Bexar County is estimated at 1,268 square miles. The population, according to the latest census, that of 1913-1914, was 119,676. EARLY SETTLEMENTS In 1718 the Spanish established the mission ot San Antonio de Valero and the Villa de Bexar near the headwaters of the San Antonio River and on the site of the present city of San Antonio. The principal natural advantage inducing settlement at this place was the existence of large springs which emerge at the head of the San Antonio River a few miles farther inland. The location for this setllement is said to have been pointed out to the Spaniards by the Frenchman, Saint Denis, as a suitable place :for a city "in the most pleasant place" in the province of Texas.t Subsequently, between the years 1718 and 1731, there was built up by the Spanish, the several missions of which the ruins still remain. Of these, the mission of San Antonio de Valero, already noted, and Conception Mission are within the limits of the present city of San Antonio. The others are farther­south, but all are within the valley of the San Antonio River, where water from the springs was available and was used in irrigation. The presence of these springs, giving rise to a per­manent flowing stream in a region otherwise lacking in surface' water supplies, determined the original location of the city of San Antonio. tClark, Robert Carlton. The Beginnings of Texas. Univ. of Texas Bull. No. 98, p, 87, 1907. *Issued March, 1920. Universityi of Texas Bulletin Settlement by citizens of the United States began in Bexar County while Texas was still a Spanish provin-0e, although not until 1820 was official permission secured to establish an Ameri­ Sand Hills: The surface exposures of the Car­rizo formation are characterized by low hills and very sandy soils. The vegetation on the hills is chiefly deciduous oaks. In Bexar County the sand hills of this belt occupy a limited area in the southern part of the county. Stream Terrace Plains: A prominent feature of the Coastal Plains part of the county is the river flood plains. These stream deposits are of different ages, from Pliocene or early Pleistocene to Recent. They are found likewise at different levels, and many of them have been cut into by erosion. Some of the larger plains are those on which Kelly and Brooks aviation fields are located. These plains are described in connection with the discussion of the Pleistocene geology. Geology and Mineral Resources of Bexar Co1~nty STRATIGRAPHIC GEOLOGY. The formations exposed at the surface in Bexar County are those of the Mesozoic and Cenozoic eras. The Mesozoic rocks of this county are those of the Lower and Upper Cretaceous (Comanchean and Cretaceous systems), this division of geo­logic time being well represented. The Cenozoic deposits are those of the Eocene, together with terrace deposits of the Pleistocene. For convenience of reference the formations found in the county are listed in the table which follows. Al­though not exposed at the surface, pre-Cretaceous formations are reached by deep wells in the northern part of Bexar County. PRE-CRETACEOUS Two of the wells of Bexar County of which records have been obtained have passed entirely through the Cretaceous formations and into older deposits. Of these two wells one is located on the Leon Springs Reservation north of the Balcones fault zone, while the other is on the Camp Bullis Reservation a few miles south of the first fault of that zone. Both wells were drilled in an effort to obtain an adequate water supply for the Leon Springs Government reservation, and in each of the wells the rocks lying next below the Cretaceous were found to be schists. In the well north of the Balcones fault zone the schists below the Comanchean formation were entered at about 1015 feet below the surface and were pene­trated 1500 feet, or to the total depth below the surface of 2500 feet. Among pebbles from the basal part of the Coman­chean in this well, Dr. J. A. Udden, who has studied the cuttings, recognizes pebbles resembling fragments of the Hickory formation of the Central Mineral region; also a few fl.int pebbles, dark in color and laminated like pebbles from the Bend series. With regard to the schists, he says, ''Samples 45 to 49 inclusive (representing cuttings from the schists) are most probably pre-Carboniferous, and in my opinion they are identical with similar material described from below 1100 feet in the boring at Georgetown in Williamson County". (lVISS.) The second well reaching into the pre-Cretaceous, on the Camp Bullis Reservation, is south of the Balcones Escarpment and within the fault zone. In this well the schists were reached at the depth of 1790 feet and were penetrated 115 feet, or to the total depth below the surface of 1905 feet. With regard to the schists of this well, Dr. Udden, who ha~ examined University of Texas Bulletin TABLE OF GEOLOGIC FORMATIONS IN BEXAR COUNTY. <:) ·3 N g ~ Formation name Q) i:l ~ Flood­ ~ plain '(i) deposits p:; Thick­ness I~-'--~~~~~:'~~ ICarrizo S-. i:l -g 2 ~ rf: ..i:: <:) i:l ol s 0 0 Edwards . Comanche Peak Glenros~ Travis PeaK ? 600± 200+ • 65 70 50± 8 O O ± 1200± Fig. 3. Table of Geologic formations together wit graphic representa­tion of the Columnar section. Ktp, Travis Peak; Kgr, Glenrose; Ke,Edwards including Georgetown; Kdr, Del Rio; Kba, Buda; Kef, Eagleford;Ka., Austin Chalk; Kt. Taylor; Kn, Navarro; Em, Midway; Ew, Wilcox; Pl, Geology and Mineral Resources of Bexar County the samples, states that the formation represented is jirobably the Packsaddle Schists of the Central Mineral Region. (Mss.) The logs of these two wells are given in the sectirm on well records. How far to the east from the Balcones Escarpment these schists lie immediately below the Comanchean formations can be determined only by subsequent drilling. The fact that the schists have been found under the Comanchean at George­town and at San Antonio indicates that they underlie those formations through a considerable north and south distance along the Balcones fault zone. MESOZOIC COMANCHEAN CRETACEOUS The formations of the Comanchean series in this county are shown in the table on page 20. They are included on the Trinity, Fredericksburg and Washita divisions as there indicated. TBAVIS PEAX POBM.ATIOK The term Travis Peak formation has been applied by Hill to the lowermost rocks of the Cretaceous of south-central Texas. This formation represents in part at least the Trinity or Base­ment sands of northern Texas. Although not exposed at the surface, the Travis Peak formation is reached by some of the deep wells in the northern and north-central parts of the county. Records have been obtained of about six wells in the county which pass into or through this formation. The well of R. Mercke at Bulverde on the Cibolo River at the north line of the county, is reported by Hill and Vaughan• as reaching a depth of 361 feet. The surface exposure at this locality is the Glenrose formation, and on the basis of the log, Hill and Vaughan have regarded this formation as extending to the depth of 137 feet. From 147 feet to the bottom of the well, 361 feet, the formation is identified by them as Travis Peak. A well drilled on the Leon Springs Reservation in this county in 1909, starting in the Glenrose formation, passed entirely through the Travis Peak formation and into underlying schists. Samples of the cuttings from the well were submitted to the *18th Ann. Rept., pt. 2, U. S. Geol. Surv., P. 272, 1898. University of Texas Bulletin Bureau of Economic Geology and were examined by Dr. J. A. Udden. A log of the well and supplementary data were sent to the Bureau by Mr. Alexander Deussen. The record from this well, which is of especial importance in determining the thick­ness of the Glenrose and Travis Peak formations, is given on a later page. From the surface to the depth of 1025 feet, the cuttings from this well are identified by Dr. Udden as Coman­chean. Mr. Alexander Deussen has assigned the strata from 535 feet to 1015 feet to the Travis Peak, indicating for the formation a thickness of about 480 feet. The third well passing into this formation is also a Gov­ernment well located on the Camp Bullis Reservation, six miles south and one-half mile east of the well on the Leon Springs Reservation. In this well the combined thickness of the Glenrose and Travis Peak formations, including Basement sand, amounts to between 1200 and 1300 feet. A fourth well believed to enter or pass through the Travis Peak formation was drilled on the Waring Estate near the Bandera Road, seven and one-half miles northwest of San Antonio. Of this well there is preserved the driller's log, but unfortunately no samples of the cuttings. A blue print record of the log of the well has been obtained from the Con­structing Quartermaster's office at Fort Sam Houston. The data for the log were preserved and the blue print record made at the time the well was drilled by Mr. F. A. Gartner. In this well the Comanchean formations were entered at 400 feet from the surface. The well was drilled to the depth of 2853 feet, thus penetrating 2453 feet of Comanchean or older sediments. The Ridder well on the Medina River southwest of San An­tonio and the Kearney Pipe Line and Oil Company well south of Leon Creek, record of which is subsequently given, probably terminate in the Travis Peak formation. As indicated by the drillers' logs and more particularly by the cutings from these wells, the Travis Peak formation under­lying Bexar C'ounty includes layers of limestone alternating with softer layers, chiefly of marly clays. The limestones, as indicated by the well on the Leon Springs Reservation, in­clude both ordinary and dolomitic layers, while the marly clays frequently contain pyrite. A phase of this formation is recorded in the logs as "red mud" or "red clay". The samples of cuttings seem to indicate that the layers so recorded include Geology and .llineral Resources of Bexar County rather soft calcareous clays or marls with, in some instances, a calcareous and ferruginous cement, together with fine sands or silts. As this formation lies unconformably on the pre-Cretaceous, its thickness may be expected to vary exceedingly. Of the structure and rate of dip of the formation, very little can be determined from the scanty records now available. North of the Balcones fault zone it is to be expected that the formation will conform to the Glenrose and have a similar moderate southeast dip. In that part of the county within and east of the Balcones fault zone, it is to be expected that this forma­ tion shares in the disturbed conditions common to the other formations of that belt, which are more fully described else­ where. GLEJIBOSE :POBllllA.TIOJI The Glenrose formation of the Lower Cretaceous ( Comanchean) age, is the eldest of the formations exposed at the surface in this county. This formation includes chiefly alternating layers of moderately hard and soft r-0cks. The harder ledges are chiefly limestone, as this formation contains almost no flint. Some of the limestone layers are fine-grained and quite hard, although as a rule the limestones of this formation are of but medium hardness. The marl layers of the formation are usually thin, being from a few inches to one or two feet thick, and rather soft. At the surface the marl layers, like the limestone ledges, are usually yellow. When buried within the earth, they may be at times gray or blue. The formation may usually be recognized by the characteristic succession of hard and soft strata, although in places the formation is more heavily bedded. Occasionally also, the heavy limestone ledges are honey-combed and under these conditions resemble the non-flinty ledges of the overlying Edwards formation. The examination of any considerable sec­tion, however, will usually afford a basis for separation from the Edwards formation. The marls of this formation have been used in road-making on some of the roads passing through this area where other ma­terials are not readily available. The calcium sulphate mineral, celestite, is occasionally found filling cavities in this formation, University of Texas Bulletin and has been mined to a limited extent near Austin, in Travis County. The sub-surface layers of the formation produce mod­erate supplies of water, and many of the wells yielding moderate supplies north of the Balcones fault zone terminate in this formation. Thickness: The fact that the base of the Glenrose formation is nowhere exposed in this county makes it impossible to measure the thickness of the formation from surface exposures. By combining surface exposures and well records, however, it is possible to determine the thickness of this formation probably within reasonatbly close limits. Perhaps the most trustworthy measurement of the thickness of the formation in this county is that obtained on the Leon Springs Military Reservation. In the deep well on the reservation, as already noted, the Glenrose is regarded as extending from the surface to a depth of 535 feet. In the hills near the well, the Edwards limestone is pro­visionally-identified as coming into the section at about the 1420 foot level. The ground level at the well is about 1156 feet above sea level. Hence to the 535 feet of this formation penetrated in the well must be added between 265 and 315 feet exposed at the surface, making a total thickness for this formation of about 800 feet. This measurement, however, may include the equiva­lent of the Walnut clays and the Comanchean Peak limestone; which, however, are of limited development in this county. Physiographic expression: The alternately hard and soft strata of this formation gave rise in the early literature to the term "alternating beds" as applied to the formation. This suc­cession of hard and soft layers occasions the characteristic ter­raced appearance already referred to as distinguishing the Glen­rose Hills. Common fossils: Among the fossils found in considerable abundance in the Glenrose, the most frequently met with are the gastropod LunatW, (Tylostoma) pedernalis and the bivalve Gyprina? mediale. Neither of these, however, is confined to the Glenrose since both are found likewise in the Travis Peak forma­tion. COl!AJl'CBE PEA.X :l'OB.lllU.TIOH The Comanche Peak limestone has not been differentiated as Geology and Mineral Resources of Bexar County a formation in this county, and in the mapping and in the measurement of sections it is included either with the Glenrose or with the Edwards. According to Hill and Vaughan this formation is present in the Austin quadrangle to the northeast of this county and likewise in the Uvalde quadrangle to the southwest, where it is a nodular, somewhat massive limestone, containing the oyster Exogyra texana. In these quadrangles the formation has a thickness of from 50 to 60 feet. Hence, although not yet differentiated, it is probably present also in Bexar County. EDWABDS l'OBKATIOlll" The Edwards formation consists chiefly of limestones. The rock of the formation as developed in this county is usually coarsely crystalline, although in this respect it is variable, some parts of the formation being particularly dense and of fine texture, approaching a lithographic stone in structure. Fre­quently both on surface exposures and deep within the earth, as indicated by well borings, the formation is profoundly honey­combed and cavernous. These openings in the rock, where ex­posed in quarrying the limestone, follow more or less the bedding planes and joint planes of the .formation. The Edwards forma­tion is especially characterized by a great abundance of flints enclosed within the limestone. These flints are in the form of layers which lie parallel with the bedding planes, or replace for a considerable space the limestone layers of the formation. Some of' the flint, however, is in the form of nodules, oval or flattened masses, or so-called "boulders" in the limestone. Upon the disintegration of the limestone, the flints remain on the surface in great profusion. Usually the Edwards limestone may be recognized by the presence of these flint masses both in the rock when seen in place, and in the residue. The soils derived from the flinty phase of the Edwards formation are prevailingly red, and the belt of country occupied is referred to locally as the "red lands." In parts of this formation, however, the flints are less abundant and exposures may frequently be met with in which no flints are observed. In the absence of fossils some difficulty may be experienced in separating such exposures from University of Texas Bullet?'.n the hard phases of the Glenrcse on the one hand, and the Buda on the other. If in such exposures the texture is found to be coarsely crystalline, the rock may be quite definitely separated from the Buda, which never presents this appearance in this county. If, on the other hand, the rock is close-grained, dense and of fine texture, the separation from the Buda can perhaps be safely made only on the fauna. Aside from the flint masses which it contains, the Edwards limestone is for the most part a very pure calcium ·carbonate. It is also, as previously noted, a very dense, hard, partly crys­tallized limestone. These characteristics make it valuable for a number of purposes. Several quarries have been opened in this formation in Bexar County for the manufacture of lime. Rock from this formation is taken from a quarry at Beckman for use as rip-rap in Government work on the harbors of the Gulf coast. The hard, dense rock of the Edwards formation, when crushed, should afford material favorable for concrete, although so far as observed no part of the formation is being so used at the present time, owing perhaps to the abundance of concrete ma­terial in this county. This rock should be of service also in road-buildin,g. Upon partial decay the rock in places assumes a soft, spongy appearance. This form of the rock has been used in road-building on the Bulverde and Blanco roads. Thickness : A full measure of the thickness of the Edwards formation has not been obtained from surface exposures in this county, but from well records the thickness of the formation is estimated to be between 400 and 500 feet. Physiographic Expression: The belt of country occupied by the Edwards formation is moderately to distinctly hilly, although in places there are areas of relatively level lands. The native vegetation is chiefly juniper and small oaks, including in places a limited amount of mesquite. The surface materials from the formation, as already noted, contain quantities of flint. The soils, especially those derived from the flinty phases of the formation, are characteristically red in color. The soil supports a good growth of grass and these lands form desirable ranch lands and are used chiiifly for this purpose. Oonvm.o1i fossils: Although not always abundant, several of Geology and Mineral Resources of Bexar County the fossils of the Edwards formation are very unusual in ap­pearance. This is true in particular of the bizarre mollusku of the genera Radiolites, Monopleura, and Requienia. Surface exposures and local details: The surface exposures of the Edwards limestone form a belt varying in width, lying immediately south of the Glenrose area and hence at the north­ern margin of the Balcones fault zone. This belt is widest at the eastern margin of the county and narrows towards the west. Where crossed by the Bulverde Road, in the eastern part of the county, this belt of the Edwards formation, including possibly the Georgetown, .has a width of over five miles. On the Blanco R-0ad the belt is somewhat narrowed. At the Fredericksburg and Babcock road-crossing, the belt is further narrowed, and at the Bandera Road crossing has a width not exceeding one-half mile. At the pit of the San Antonio Lime Company, on the Fred­ericksburg Road 16 miles from San Antonio, the limestones of the Edwards ~ormation are well stratified, consisting of layers of hard rock varying £rem a few inches to four or five feet in thickness. Some layers of the rock ·contain numerous small cavities produced iby ground water. Flint layers are present usually lying parallel with the bedding planes, although flint concretions are seen, and occasionally flint ~eposits are found filling joint planes. The solution cavities also are more or less lined with silica. The limestone rock is heavy and upon close examination is seen to be in places minutely banded. The right bank of Helotes Creek below the Bandera Road crossing affords a good exposure of this formation. The creek here follows on or near the main fault line separating the Glen­rose and the Edwards formations. GEOBGE'l'OWJ!I' J!'OBKA'l'IC'W Lithologically the Georgetown formation if present in this area is very similar to the Edwards, and in the mapping and columnar section these formations are not separated. This treatment of the two formations has seemed the more necessary since in well logs there is almost no opportunity to separate them. An exposure which probably represents the Georgetown is seen on the Bandera Road, 17 miles from San Antonio. The University of Texas Bulletin limestone rock exposed here, lying immediately below the Del Rio clay, is a very hard, close-grained rock, containing little or no flint. In the eastern part of the county a similar rock is seen lying below the Del Rio on the Peter Clausen ranch, 11h mile north of the Nacogdoches Road. The Georgetown formation in the Colorado River section is reported to have a thickness of from 65 to 70 or 80 feet. In the Uvalde folio the formation is estimated by Vaughan to have possibly a thickness of 40 feet. These two formations, the Edwards and Georgetown, are of special economic importance in this county as the chief large water-bearing formations of the area. DEL BIO J'OBllltA.TIO:N The Del Rio formation consists largely of days which on surface exposure are usually yellow, but when encountered below the surface are usually blue in color. The clays of this formation contain in places great numbers of fossils, especially of the small oyster Exogyra arietina. Occasionally these shells are cemented together iby calcareous or ferruginous cement forming indurated layers within the day beds. The formation contains more or less iron sulphide as pyrite and in well cuttings the amount of pyrite is not infrequently found to be considerable. On the surface exposures gypsum in small quantities is not in­frequently observed in the clay. Thickness: No surface exposure has been found in this county in which the whole thickness of this formation can be measured. In the records of wells, however, the formation is quite uniformly reported as having a thickness of from 50 to 70 feet. Rarely does-tbe reported thickness of the formation fall below or rise above these limits. In Bexar County this formation is quite generally known to the well drillers as the "mud hole" or the "second mud", or the "big mud". These names have uri~i­nated because of the charade;~ and position of the formation. It is known as· the "mud hole" because the clay when churned up by the drill becomes mud. The term "second mud" is sometimes applied to it because a formation at a higher level, the Eagle­ford, frequently contains enough clay to cause cable tools to stick, and hence gives the formation the character of mud. The Geology and Mineral Resources of Bexar County origin of the term ''big mud" is similar. As the Del Rio forma­tion has a thickness of from 50 to 70 feet while the clayey phase of the Eagleford rarely exceeds 30 to 35 feet, the Del Rio has come come to be known as· the "big mud". Physiographic expression:, The Del Rio formation, being chiefly a relatively non-resistant clay lying between relatively resistant limestones (the Georgetown-Edwards series below and the Buda limestone above), is found as a rule on surface ex­posures to occupy a valley, or the abrupt slope from an upland to the valley. The soils derived from this formation are black or brownish in color. The timber growth is chiefly mesquite, and frequently the Del Rio outcrop when in avalley may be followed by the dense growth of mesquite, differing in this respect from the mixed growth of timber, chiefly oak and juniper, found on the hard phases of the limestone formations. Common fossils: As already noted, the small oyster, E xogyra arietina, is a very characteristic index fossil of this formation, and its stratigraphic equivalents. This fossil is particularly aibundant in the lower part of the formation. Near the top the deposits become relatively unfossiliferous. A fossil occasionally found in the upper part of the formation is the oyster, Gryphea muetronata. Lithologically, the beds change somewhat towards its upper limit, becoming more calcareous and including in places shelly lime rock. Near the contact with the Buda is seen occa­sionally a soft, light-colored phase of the formation superficially resembling in a degree the partially disintegrated phases of the Eagleford formation. Surface exposures and local details: The surface exposures of the Del Rio formation are found throughout a belt of country next south of the exposure of the Georgetown-Edwards forma­ tions. The formation being thin, this belt of surface outcropping is relatively narrow, usually not exceeding a half mile. There are, however, some localities where the belt of surface exposures of this formation is widened, owing to minor faulting, which brings the formation successively to the surface. This belt of minor faulting is crossed on the Fredericksburg Road from 10.2 to 13.2 miles from San Antonio, and on the Babcock Road from 12 to 15 miles from San Antonio. Within this belt on the Fred­ University of Texas Bulletin ericksburg Road, owing to a combination of faulting and folding together with variations in surface level, the Del Rio formation shows itself in five successive belts as follows : First belt, from 10.2 to 10.3 miles from San Antonio; second ibelt, from 10.5 to 10.7; third belt, from 11.4 to 11.6; fourth belt, from 11.9 to 12.3; fifth belt, from 12.7 to 13.2 miles. On the Babcock Road, suc­cessive belts of this formation come in as follows: First belt, 12.05 to 12.1 miles from San Antonio; second belt, 12.4 to 12.5; third belt, 12.6 to 12.7; fourth belt, 12.8 to 12.85; fifth belt, Valley of Leon Creek probably occupied chiefly by this forma­tion, about 13 to 13.5 miles. The formations alternating with 1lhe Del Rio in these ex·­posures are the underlying Georgetown-Edwards and the-·over­lying Buda, including the Eagleford and a part of the Austin. As already stated, the successive exposures of the formation are due in part to faulting and in part to changes in the surface elevation. East of the Leon Springs Reservation in this county and also west of the Bandera Road, this formation so far as observed appears as but a single belt with usually but few actual surface exposures. On the Blanco Road the belt is crossed, without any observed exposures immediately on the road, at about 12 miles from San Antonio. On the Bulverde Road, the Buda formation is well exposed at the foot of a north-sloping hill 13.5 miles from San Antonio. Although no exposures of the Del Rio clays are seen on the road, this formation may be expected to occupy the valley at the foot of this hill and to extend to the limestone hills which begin on this road at about 13 miles from San An­tonio. To the east of the Bulverde road the Del Rio formation has not been traced in detail, but is to be expected as a rela­tively narrow belt extending as mapped in a general northeast­ward direction to the county line at the Cibolo River. Near the county line an exposure is seen at a water-tank on the Clausen Ranch, 1112 miles north of the Nacogdoches Road crossing of the Cibolo River. West of the Bandera Road exposures of this formation continue for two or three miles, beyond which the belt narrows and the formation in places is faulted out of sight. The Del Rio formation is extensively used in its belt of sur­ Geology and Mineral Resources of Bexar County :n face outcropping in the construction of ponds. On the Bandera Road a pond made from this formation is seen near Helotes Creek 17 miles from San Antonio. The clays of the formation are utilized in making a pond on the Clausen ranch, near the east county line, llh miles north of the Nacogdoches Road. At these. localities the small fossil ExogY1·a arietina is extremely abundant. BVDA rOBJllU.TIO:S The Buda formation as developed in this county is quite uniformly a close-grained, dense, hard limestone. On surface exposures this rock is usually light-colored, or tinged with gray, yellow, or blue. As seen in well cuttings, the limestone is usually of light color, although a part of the formation fre­quently shows as a blue rock. Black specks in the limestone is a characteristic frequently referred to by drillers in describing the cuttings from wells. The change in sedimentation from the Del Rio to the Buda and from the Buda to the Eagleford formations appears to have been abrupt, there being little or no gradation between the formations. The hard limstone of the Buda formation lying between the softer rocks of the Del Rio and Eagleford forms a horizon both conspicuous and readily followed on the surface. The Buda limestone in this county is but little utilized at the present time. Its hardness and close texture indicate that as here developed the limestone would be suitable for concrete material. Thickness: Both in lithologic characteristics and in thickness the Buda formation is perhaps the least variable of the Creta­ceous formations as developed in this county. Well records indi­eate that the Buda limestone is here quite uniformly between 55 and 65 feet thick. Rarely is the formation reported to vary beyond these limits. Physiograpkic expresswn: In its surface exposures the Buda limestone appears as hard, thickly bedded rock. The surface is frequently rough owing to partial dissolution through the agency of surface waters. The soils derived from the formation are dark colored and usually relatively thin, including many rock fragments. When found capping hills the soils from the Buda University of Texas Bulletin formation support a rather heavy growth of timber made up chiefly of oaks. In this respect, the Buda formation resembles the hard rock phases of the Austin formation. Common fossils: The Buda limestone on surface exposure~: is usually found to contain fossils, sometimes in considerable num­ber. The shells of invertebrates have, however, for the most part been replaced or filled with a m~neral deposit, probably usually calcite. Hence the fossils are seldom easily removed from the matrix, and are with difficulty used in identifying the formation. Thin sections of the rock have shown that in this formation are found numbers of foraminifera. * Lithologically the formation may be in a measure recognized by its uniformly close-grained, dense structure, although similar dense masses of rock are found also at places in the Georgetown and Edwards formations, and less distinctly so in the hard rock phases of the Austin formation. The position of the Buda limestone, lying between the lithologically very different Del Rio and Eagleford formations, assists materially in locating this formation on sur­face exposures and in well drillings determines its position definitely. Sw·face exposures and local de.tri·ils: The Buda formation in Bexar County comes to the surface in a relatively narrow belt having a general northeast-southwest trend. On the Bulverde Road the rocks of this formation are exposed near the base of a north-sloping hill about 13.5 miles from San Antonio. The for­mation .here dips into the hill under the Eagleford and Austin formations, the belt of exposed rock being narrow. So far as observed the rocks of the Buda are not again exposed on this road. To the east of the road the line of outcropping of this formation has not been traced in detail although it is known to continue in a general northeast direction to the county line. A small anticline in this formation is observed at the Salado Creek crossing of the Blanco Road. Just above this crossing as much as 35 or 40 feet of the Buda formation is exposed in the right bank of the stream. Downstream the Buda disappears be­ neath the Eagleford and Austin formations within about one­ £ourth mile below the road crossing. When followed upstream --.U. S. G·eol. Surv., 18th. An. RJ?t. pt. 2, p. 228, 1898. Geology and Mineral Resources of Bexar County the rocks of the Buda formation are found likewise to dip below the stream level, giving place to the Eagleford and Austin formations in the stream banks. However, the Buda reappears in this stream within about three-fourths or one mile further upstream, indicating a relatively limited development of the west slope of the anticline. On the Blanco Road the Buda is exposed at the Salado Creek crossing, and again between eleven and one­half and twelve miles from San Antonio. On the Fredericksburg and Babcock roads the Buda formation is found to share in the minor faulting which, as already men­tioned, brings these thinner formations repeatedly to the surface. On the Fredericksburg Road the Buda formation is first met with lying below the Eagleford formation a short distance beyond the Lockhill-Selma Cross-road, about 10.1 miles from San Antonio. It is last seen on this road at the Bacon Ranch cross­road, 12.7 milt>..s from San Antonio. On the Babcock road the formation appears at intervals from 12 to 12.9 miles from San Antonio. On both of these roads this formation alternates by changes in surface elevation and by faulting with the Del Rio and other formations. The belt of Buda exposures may be seen at intervals as far west as the Hoffman Ranch, about three miles west of Helotes Creek. Beyond this place the belt of Buda exposures narrows and the formation shows but limited exposures to the Medina County line. The place of the formation below the surface is recorded in well records throughout most of the central part of the county. From its surface exposures the formation dips with variations due to faulting and folding toward the south and southeast. At the northern limits of the city of San Antonio this formation may be expected at from 300 to 350 feet beneath the surface, depending upon variations in surface elevation. At the southern city limits, six miles farther south, owing to steep dips and faults, this formation lies much deeper and is there encountered in well drilling at between 1200 and 1300 feet. A few miles farther south, near the ChaYanneux Cross-road, it is found by well drilling to ibe buried to a depth of 1600 or 1700 feet. 3-Bex. University of Texas Bulletin UPPER CRETACEOUS The Upper Cretaceous series is well represented in the Bexar County section. The formations in order, beginning with the oldest, are: Eagleford, Austin, Taylor and Navarro. EAGLE:POBD :POBMATIOJ!I' The Eagleford formation as developed in Bexar County includes a very characteristic series of calcareous a11d more or less sandy shales. The rock is granular in appearance, and breaks horizontally into thin slabs, giving a :fiaggy appearance. With this light-colored :fiaggy rock are found frequently layers of much harder indurated clay-lime rocks. These interpolated layers frequently have a thickness of from one-half to one foot or more and are probably continuous over considerable areas. The formation is to some extent bituminous and when encoun­tered in drilling is frequently of a dark color. It also contains sufficient clay material in parts of the formation to cause the tools to-stick more or less in drilling. For this reason the forma­tion is sometimes known to the drillers as the ''first mud'' (the Del Rio formation being the ''second mud''). To most of the drillers in the central part of Bexar County this formation is known as the ''lignite''. This name, although scarcely justified by the characteristics of the formation, is firmly fixed in the nomenclature of the drillers of this county. It is not to be con­fused, however, with the true lignite deposits which are found in much later formations (Tertiary) not represented in the central and northern parts of the county. Thickness: The Eagleford formation is relatively thin in Bexar County. Practically all well records place the thickness of this formation at from 30 to 35 feet. In a few records this thickness is exceeded slightly, while in others the thich."lless is recorded.as less, the formation being recorded as absent in a few wells. With regard to the reported absence of the formation in wells, it is not impossible that occasionally a well is so located with respect to a fault that this formation is missed in drilling. Such would be the case i£ the well were located at a place where the Austin formation is faulted against the Buda formation. On Geology and Mineral Resources of Bexar County the other hand, the aprarent thinness and possibly the supposed absence of the formation may also be due to local mduration in the formation so that it is not recognized in drilling. Two ex­posures have been found in the county in which it is believed that the full thickness of this formation is shown. Both of these exposures are on Salado Creek near the Blanco Road crossing, one below and one above the crossing. In these exposures the base of the formation, resting upon the Buda limestone, is defi­nitely limited. The top of the Eagleford where this formation passes into the Austin formation is much less definitely marked. It appeared to the writer, however, that not more than about 30 or 35 feet of the exrosure at these localities can be referred to the Eagleford formation. Physiographk expression: The exposures of the Eagleford are scarcely extensive enough to develop well marked topographic features. However, as the formation is softer and less resistant than either the Buda below or the lower part of the Austin above, the formation when exposed on relatively level land is usually represented by a slight although more or less well­marked valley. On steep hill slopes the rocks of this formation, though in themselves characteristic by their lithologic characters, do not notably affect the surface features. Common fossils: Among the characteristic fossils which may be frequently utilized in identifying the Eagleford formation are plant stems and fragments, fish scales and shark's teeth. As developed in Bexar County, the formation is rather more lacking in plant remains than at some other localities. Fish scales and teeth are occasionally present, although rarely abundant. However, the lithologic characters of this formation are so distinctive that little or no difficulty will be experienced in locating the formation on surface exposures. In well drillings likewise the place of the formation is readily recognized by its place between the Austin and the Buda formations. Surface exposures: As the Eagleford is· the thinnest of the formations recognized in Bexar County, the surface exposures are correspondingly limited. The belt of surface exposures of this formation is closely associated with the belt of exposures of the Buda formation already described. On the Bulverde Road University of Texas Bulletin it is found exposed, as already noted, with and just above the Buda formation at about 13.5 miles from San Antonio. On the Blanco Road are found the exposures of the full thickness of this formation on Salado Creek which have previously been mentioned, and also an exposure in the road on the hill b~·yond the creek. An isolated exposure of this formation is seen also on a small stream on the Lockhill-Selma Road, slightly south of west of the Blanco Road crossing on Salado Creek. On the Fredericksburg and Babcock roads the formation is first crossed at about 10 and 11 miles respectively from San Antonio. In the western part of the county the formation is found in a narrow belt too limited to map except by exaggeration. Exposures may be seen on Canyon Creek on the Hoffman Ranch, within a few miles of the west boundary line of the county. In its sub-surface position, the Eagleford formation partakes of the general southward dip, passing under the later formations The depth at which it may be expected from the surface may be deduced from the structural contour map accompanying this report, on which the actual level of the top of the Del Rio forma­tion is indicated. The stratigraphic interval from the top of the Del Rio to the base of the Eagleford is about 60 or 65 feet. A'USTDI' POBllltA.'1'10B' The Austin formation includes a thick deposit of limestone, chalk, and marl. The lower beds of the formation are hard limestones. Hi.gher up the formation passes into a more chalky and as a rule softer phase, while near the top the deposits be­ come chalky marls. The formation is stratified and consists in places of alternating harder and softer beds, which on weather­ ing give a banded appearance, in some instances not entirely un­ like that of some exposures of the Glenrose formation. On sur­ face exposures the rocks of this formation are prevailingly creamy yellow, while in sub-surface exposures the rock is either blue, white, or yellow. In drilling, the cuttings from the upper part of this formation, including perhaps one or two hundred feet, as they come to the surface are blue in color and resemble a clay or mud and are in some instances so recorded in the drillers' logs. At lower Geology and Mineral Resources of Bexar County :n levels the formation is white or yellow in color and is usually somewhat harder than near the top. This phase of the forma­tion is often referred to as the ''Magnesian'' rock, although so far as known, it is a calcium carbonate. Beneath the "magne­sian'' phase of the formation are the harder limestone layers al­ready referred to, often described in well logs as blue, gray, white, or yellow limestones. The chalk rock of the Austin formation is used near San An­tonio in the manufacture of portland cement. The harder lime­stones from the lower part -0f the formation are used for con­crete. The formation yeilds moderate supplies of water, although frequently containing more or less hydrogen sulphide gas. The oil of the Alta Vista and Mission fields is from this formation. Thickness: The thickness of the Austin formation is difficult of exact measurement either on surface exposures or from well records. No locality has been found in the· county where the full thickness of the formation can be measured at the surface. On the other hand, in the well logs it is extremely difficult if not impossible to determine the level at which the drill passes from the Taylor to the Austin formation. The most trustworthy measurements of the formation are those obtained from wells known to be located near the contact line on the surface of the Austin and Taylor formations together with data from wells passing entirely through the whole Upper Cretaceous. Of a number of wells so located, the following may be cited as afford­ ing the most trustworthy records available. The average ob­ tained from these wells indicates a thickness of between 300 and 400 feet. The Government well at the old target range, now the aviation post, on the Austin Road, 6 miles from San Antonio, is probably located within the belt of Taylor exposures but quite near the Taylor-Austin contact. In the bed of Salado Creek about one mile northeast of the well and at a level approximately 75 feet lower, is an exposure placed by Dr. Stephenson as the probable Taylor-Austin contact. Judging from the surface exposures at the well and from this exposure in the stream bed it is probable that as much as 50 or 75 feet of the deposits at the well are to be referred to the Taylor formation. In this well the base of the Austin was recognized at the depth of 353 feet. University of Texas Bulletin In the log this interval is divided up as follows: ''Soil, 2 feet; yellow and blue clay and soft limestone or shale, 218 feet; and chiefly hard limestones, light gray, blue-gray, and white, 133 feet". On the basis of the data given above, it is probable that between 275 and 300 feet of this interval is to be referred to the Austin formation, representing the full thickness of the forma­tion at that place. A well on the Waring estate near the Bandera Road, 7~ miles from San Antonio, is believed to be located within the belt of surface exposures of the Austin formation or with only a thin covering of the Taylor. In this well there is recorded beneath the surface soil and gravel, 145 feet of "blue clay", and 155 feet of yellow, white, and blue limestones, giving a total of 300 feet, all of which with the possible exception of some clays near the surface is to be referred to the Austin forma­tion. A well drilled at Schertz on the Cibolo River is also near the contact line of the Austin-Taylor formations. A short dis­tance upstream from this well are found surface exposures of the Austin formation, while immediately downstream are ex­posures of the Taylor formation. In this well there are recorded 14 feet of yellow clays, 215 feet of blue clay, and 149 feet of magnesian and other limestones. This would seem to indicate a possible thickness of 378 feet for the Austin. However, upon other data it is suspected that a fault or a very steep dip passes immediately north of this well; that is between the well and the exposures of the Austin formation. If this is true, only a part Qf the 229 feet of yellow and blue ''clays'' of this record is to be referred to the Austin formation. A well at the residence of A. E. Goforth on the Culebra Road, 18 miles northwest of San .Antonio, appears to be located near the contact line of the Austin-Taylor formations. In this well the base of the Austin was recognized at the depth of 349 feet, all of which apparently, aside from the surface materials, is to be referred to the Austin formation. From these records it appears that the Austin formation in Bexar County in its belt of surface exposures, approximates 300 feet in thickness. From the record of a considerable number of wells drilled south of the belt of surface exposures it appears probable that the formation thickens toward the south. Among­ Geology and Mineral Resources of Bexar County the wells which indicate a thickening of the limestones southward are the following: City water supply wells on Market Street in San Antoino, hard rock above the base of the .Austin about 380 feet; City water supply well near Conception Mission in south San Antonio, magnesian and other limestones, 417 feet, with blue clays above; Ho:ffheintz well, southwest city limits, mag­nesian and other limestones, exclusive of overlying blue clay, 310 feet; Hill and Roby well, 7 miles south of San .Antonio, magnesian and other limestones, exclusive of overlying clay, 480 feet. In the Benke well on the Culebra Road near the west county line, limestone above the Eagleford are reported through an interval of 485 feet, which if referable in full to the .Austin, represents the maximum recorded thickness of the formation in the county. With due allowance for the indefinite record afforded by the well logs, it appears that the harder limestones of this formation vary in thickness. In the columnar section the thickness of 350 feet is assigned to the formation, which is probably an average, being neither the maximum nor the mini­mum thickness in the county. Physiographic expression: The .Austin formation appears on surface exposures under two different phases corresponding to the hard and soft rocks of the formation. The limestones of the lower part of the formation, when exposed, usually make up ranges of hills having a northeast-southwest trend. On these hills the soils are thin and contain considerable rock debris. The timber growth includes a preponderance of oaks with relatively little mesquite. This phase of the formation where exposed usually forms a conspicuous feature of the landscape and the belt of the hills may often be seen and its trend across the county mapped, at a distance of some miles. The softer rocks of the upper part of the .Austin formation, however, present on surface exposures entirely different topographic features. The country underlying the exposures of this part of the formation is usually gently rolling with rounded hills and gentle slopes. The native timber is largely mesquite. The soils are black and at the present time the lands are largely cleared for agricultural purposes. This physiographic development corresponds to the upper 150 or 200 feet of the formation as now delimited. Urlliversity of Texas Bulletin Common fossils: The Austin formation is highly fossiliferous and a large number of species of marine invertebrates is included in the fauna. Among conspicuously abundant fossils of the lower limestones of the formation are the oysters, Grypkea auceUa and Exogyra laeviuscula. These fossils are particularlly abundant in certain layers of the limestones of the Austin forma­tion. One of the best exposures showing these fossils is found in the rock quarry near the north side of San Pedro Park where the fossil horizon includes a ledge of rack from one to two feet thick, lying five or six feet above the base of the exposure. A similar fossiliferous ledge appears in the Ling Quarry at the west side of San Antonio River at the north city limits, lying near the base of the exposure. From a well drilled nearby, it is known that the base of the Austin formation at this place lies about 100 feet below the bed of: the river, hence unless affected by concealed faulting the horizon of these fossils at this place is between 100 and 125 feet above the base of the formation. A notable exposure of a similar fossiliferous bed of the Austin formation is seen in the bluffs on Leon Creek near th~ Bandera Road crossing. The upper beds of the formation contain considerable numbers of the large oyster, Exogyra ponderosa,"' found also in the Taylor formation. This oyster is believed not to extend its range be­low the softer beds of the upper part of the formation, being apparently absent from the hard limestones of the lower beds. This fossil is ~ound in the upper part of the formation at many localities. At the Bandera Road crossing on Leon Creek, the species seems to extend its range downward to the top of the hard limestones of the formation and to within a few feet of the level of the Gryphea bed. Surface exposures and local details: Surface exposures of the Austin formation are found throughout a broad belt having a northeast-southwest trend across this county. The Aust~n belt is somewhat interrupted in part by surface erosion and in part by terrace deposits, but more especially by faulting and folding *The Exogyra of the Austin formation, according to Bose is specifically dis~inct from E. ponderosa of the Taylor formation. Univ. Texas Bull., No. 1902, 1919. Geology and Mineral Resources of Bexar County by which other formations are interpolated into the belt of country otherwise occupied chiefly by this formation. On the line across the Austin formation in the eastern part of the county marked by the Bulverde and Perrin-Beitel roads, there are two distinct belts of Austin. The northern belt of Austin exposures is crossed on the Bulverde Road from 11/2 miles north of Wet­more to Wetmore; the southern belt is crossed on the Perin­Beitel Road from about 11;2 miles south of Wetmore to Fratt station on the Austin Road. On the Blanco Road extending due north from San Antonio, are likewise found two belts of the Austin formation. On this road, however, the northern belt is found to be much wider than on the Bulverde Road, having a width of about five miles. The southern belt on the other hand is much narrowed, having a width probably of scarcely :more than a mile. This southern belt, as indicated in the mapping, passes below the surface within the city of San Antonio, giving place to the Taylor formation. The broad belt of surface exposures of the Austin formation is crossed on the Culebra Road from Leon Creek to about 181/2 miles from San Antonio. From surface exposures it is known that the Taylor formation lies on this road both at the south­eastern and at the southwestern boundaries of the Austin ex­posures. The evidence relating to structure of these formations is more fully presented subsequently. The high lands of the central part of this belt present surface exposures that on litho­ logic characters must be placed as well . down in the Austin formation. The Potranca Road which branches off from the Culebra Road at the Leon Creek crossing, and runs slightly south of west, affords for some miles exposures which are prob­ably near the top of the Austin, many of them containing an abundance of Exogyra ponderosa. However, from about Medio Creek to the county line, this road in places affords exposures including the Gryphea zone that are to be referred to the lower half of the Austin formation. In its sub-surface position, this formation presents the char­acteristics of the other formations of this part of the state. In general the dip is to the south or south~st. The southernmost well in this county in which the formation has been definitely University of Texas Bulletin recognfaed, is that on the J. K. Lamb property 16 miles south and 21h miles east of San Antonio. At this place the top of the formation lies approximately 1600 feet below the surface. To the southeast the formation lies somewhat deeper. From the log of the Bradley and Winters well at Saspamco it appears that the formation at the county line on the Goliad Road altho not reached must lie at least 2500 feet from the surface. The rock bluffs and cliffs at the west side of Brackenridge Park in San Antonio are composed of this formation and afford good exposures of the heavy limestones. The Ling rock quarry just across the city limits at the north side of the park, is opened up also in the Austin formation. In a well drilled at the north city limits in Brackenridge Park, in 1918, a log of which is given elsewhere, the Eagleford shales were recognized at the depth of 101 feet. It is thus seen that the exposures in Brackenridge· Park and in the rock quarry north of the park lie within the lower part of the Austin and represent the formation from about 100 to 140 or 150 feet above its base. The rock as seen at these exposures is light-colored or tinged with yellow; it is evenly bedded, consisting of layers from six inches to several feet in thickness. Pyrite nodules originally on the limestone have be­come oxidized and are represented by spots or nodules of rusty­colored iron oxide. Near the base of the section at the quarry is a layer in which a small Gryphea is very abundant. At the west limits of Alamo Heights, overlooking the valley of Olmos Creek, there is a bluff into which a quarry has formerly been opened, representing a phase of the Austin formation similar to that seen in Brackenridge Park. The Gryphea layer at this exposure lies 45 feet or more above the stream bed, indicating that the section here affords an exposure lying a little lower in the forma­tion than the exposures at Brackenridge Park. Immediately west of the West Texas Military Academy, a little more than a mile north of the north city limits of San Antonio, is another west-facing bluff, exposing a similar section of the Austin forma­tion. The exposures of this formation at the cement plant two miles north of the city limits are described elsewhere. At San Pedro Park are seen exposures of the hard limestones of the Austin formation from which springs emerge. The exposures Geology and Mineral Resources of Bexar County here described lie within and represent an upthrust block of the Austin formation which forms the range of Austin Hills indi­cated on the sketch map (Fig. 2). The southernmost exposure seen of this belt of Austin is found near the intersection of Zal­zamora and Ruiz streets in west San Antonio, where a much later phase of the formation is seen, consisting of soft marly rock. To the northeast, exposures of this belt of the Austin formation may be seen to the county line at the Austin Road crossing on the Cibolo River. Particularly good exposures are seen at the cross­ing of the Austin Road on Salado Creek, and at the Perin-Beitel Road crossing of a tributary entering from the east. On these exposures Baker has made the following notes: When fresh the chalk has a light bluish-gray color while on weathered exposures it is light yellowish-buff, passing upward, upon weathering, to a brown substance resembling marl. It is much jointed in very irregular fashion and breaks often with a semi-con­choidal fracture. Nodules of pyrite are present which weather to limonite. Some beds of the rock are slightly more indurated than others and so stand out more prominently on exposed surfaces. This rock forms the bed rock at Fratt. Near the mouth of the small creek tributary to Salado Creek and heading northeast of Fratt, the dip (probably not true dip) is 1° S 65 ° E. About one-fourth mile downstream and about 200 yards above the junction with Sal­ado Creek, the dip (perhaps not maximum) is 4° to the south. In the soft chalk rock of the Austin formation at the crossing of the Perrin-Beitel Road near Fratt, Stephenson has noted the presence of the following fossils (Mss. notes) : Scaphites sp., Placenticeras sp., and a large Baculites. In the more indurated rocks of this formation about one mile farther west, he notes the presence of the following fossils: Exogyra laeviuscula, Avicula?, Pecten sp., Liopsitha elegantula (Roemer) 1, Barbatia sp. Exposures in the large belt of the Austin formation passing through the county north of San Antonio are too numerous to receive separate description. This belt of the Austin is crossed by all roads running north and northwest from San Antonio. At the Leon Creek crossing on the Bandera Road are seen good bluffs exposing the hard limestones of the formation including in some layers an abundance of fossils. Other good bluffs are seen University of Texas Bulletin at the first and second crossings of the Culebra Creek on the Culebra Road. At the Salado Creek crossing of the Bulverde Road, the bluffs seen at the right are a part of the limestones of the Austin formation and represent the west margin of the block originating in San Antonio. 'r.6.YLOB J!'OBXA.TIOl!I' The Taylor formation includes chiefly marls and calcareous clays. In surface exposures and to the depth affected by weathering, the clays are y~llow, although where unaffected by weathering they are for the most part blue in color. As a water-bearing formation, the Taylor is of but slight importance as the marls and clays are too close in texture to carry large quantities of water. The bentonite deposits of this county probably lie within the Taylor formation. The fuller's earth deposits are either near the top of this formation or in the next later formation, the Navarro. The gas of the Gas Ridge field is probably from this formation, while the oil of the Somer­set field appears to be either from this or from the Navarro formation, or possibly in part from the Midway. Thickness: A measurement of the thickness of the Taylor formation is extremely difficult. No surface exposures found in Bexar County are adapted to that purpose while in well records, it is difficuli to determine from logs or from cuttings, the depth at which the formation is either entered or passed through. In the Terrell well six miles south of San Antonio there was assigned to this formation by Hill and Vaughan• a thickness of about 400 feet. In the Alta Vista oil Fields the combined thickness of the Navarro and 'l'aylor formations, if present, apparently does not exceed six or seven hundred feet, although here a part of the Navarro may have been removed by erosion.** In the Kearney· test well for oil south of Leon Creek, the combined thickness 0£ the Navarro and Taylor formations may be as much as 900 feet. In the columnar section, this formation has been *Hill, R. T. and Vaughan, T. W., 18th Ann. Rept. U. S. Geol. Surv., Part II. **Record of Elder-Wolf well. Geology and Mineral Resources of Bexar County assigned a thickness of 450 feet which may be regarded as an average thickness where the formation is fully developed. In the Mathey well of the Bexar Petroleum Company the Ter­tiary as noted subsequently under the discussion of the thickness of the Midway formation, appears to extend to the depth of between 1340 and 1402 feet, while the Austin formation accord­ing to the driller was entered at 1892 feet and continued to the bottom of the "'ell 2025 feet. If this is true there remains for the Taylor and Navarro formations at this place a combined thickness of not more than 552 feet. The reduced thickness of these formations may of course be accounted for by possible erosion from the top since the Tertiary-Cretaceous contact is very· probably an erosion unconformity. Samples of cuttings from this well from 1938 feet and below submitted by the driller and examined by Dr. J. A. Udden apparently represent the Austin formation. Physiographic expression: Much of the area underlain by the Taylor formation in this county consists of a level plain often gravel covered by terrace deposits. When subjected to stream erosion, the hills formed from the Taylor marls are rounded, with moderate slopes. The soils derived from this formation are black and in wet weather very sticky. The prevailing timber growth is mesquite. Common fossils: The lower part of the Taylor formation contains an abundance of the large oyster, Exogyra ponderosa, which is also present as already noted in the upper part of the .Austin formation. The Taylor formation may be separated from the .Austin probably within approximate limits upon litho­logic characters, particularly by the presence of an increased clay ingredient. Ji'rom the overlying Navarro formation it may be separated pr0bably also within approximate limits. Glauconite is usually more or less abundant in the Navarro, while it is present in much smaller quantities, if at all, in the Taylor. The following notes on the Taylor formation have been made by Stephenson (manuscript notes):­ Taylor marl, consisting of weathered greenish-gray, calcareo11s clay, is poorly exposed in the west-facing slope of Salado Creek at U'llliversity of Texas Bulletin the crossing of the Seguin Road about four miles north by east of the post-office building at San Antonio. The thickness exposed ia about 10 feet. It is overlain by a Pleistocene gravel bed and the latter is overlain by sandy loam. The Pleistocene is 15 or 20 feet thick. On the east-facing slope of Salado Creek Valley about one mile above the crossing of the Missouri, Kansas and Texas Railroad, the followin·g section is exposed along a private roadway or trail: Section Feet Pleistocene: 3. Yellow sandy clay loam with lines of pebbles at irregular intervals ................16 2. Bed of gravel with chiefly flint pebbles and cobbles ........•................... 8 (Unconformity) Cretaceous (Taylor): 1. Gray calcareous clay or shale with a few poorly preserved fossils. . . . . . . . . . . . . . • • 6 From the Taylor (layer No. 1) obtained the following fossils (Collection No. 182): Hamulus onyx Morton Ostrea plumosa Morton Anomia argentaria Morton Paranomia sp. Pecten sp. (small) Liopistha (.Cymella) bella (Conrad)? Bluff on Salado Creek, left bank, 3 % miles due east of Alamo Heights, Bexar County, Texas. Section Feet Pleistocene: Irregularly bedded loam and calcareous sand and gravel. The sand and gravel are ex­tremely calcareous in places, consisting chiefly of a spongy mass of lime. In places the chief matrix of the gravel is spongy lime. F'requently pebbles are noticed with concentric layers of lime about them ............ : .•...•......20 (Unconformity) Cretaceous (Taylor): Gray (greenish gray to yellow where weath­ ered) calcareous shaly clay carrying a Geology and Mineral Resources of Bexar County few poorly preserved fossils. The shale contains occasional seams of gypsum .... 2 5 The fossils collected include: Lima (young individual) Pecten (small) Two feet of relatively soft bluish-gray chalk is exposed in the bed of Salado Creek, about a half mile above the preceding. The following poorly preserved fossils were obtained (Collection No. 184): Inoceramus sp. Ostrea plumosa Morton Placenticeras sp. Crustacean (fragment) This locality is one mile below the crossing of the Austin Road. The rock is probably at the extreme top of the Austin chalk. Surface exposures and local details: Surface exposures of the Taylor formation are found in successive belts which extend in a general northeast to southwest direction across the county. Owing to structural features subsequently to be described, the belts of exposures of the Taylor formation in part surround Austin exposures. The northernmost belt of Taylor is that which lies on the north side of the Austin exposures on the Culebra Road. The Taylor in this belt extends north to within a mile or less of the Balcones escarpment. Exposures represent­ing this formation may be seen on the property of H. Wehmeyer, H. Mossman, and R. Brown, north of the Culebra Road. Ex­posures may be seen also farther east on the Hoffman Road on the property of R. Brown and G. Wehmeyer, where the clays are utilized in making ponds. At many of these exposures, particu­larly those on the _Brown and Wehmeyer properties, the fossil Exogyra ponderosa is abundant. This belt of Taylor apparently terminates somewhat east of the Hoffman Road at the north turn north of the Steubing cross-road. A large area of Taylor exposures lies south of the main Austin exposures. At the west county line these exposures are found north of the Castroville Road, and extending northeast, lying somewhat south of, and approximately paralleling the Potranca Road to the Leon Creek crossing. East of Leon Creek the Taylor is seen on the Culebra Road at a cut in the road 8 miles from University of Texas Bulletin San Antonio. At about this place, the Taylor belt is divided iby a southward projecting nose of Austin exposures. On the Fredericksburg Road, marls containing Exogyra ponderosa are seen from 9.3 to 9.7 miles from San Antonio. In the city of San Antonio, the Taylor exposures are again divided by a southward projecting nose of the Austin formation. The western area of Taylor marl is interpreted as crossing the Bandera and Fredericksburg roads at from 2.6 to 6.6 and from 2.5 to 5.4 respectively miles from San Antonio. This Taylor belt may be expected to narrow farther to the east, and probably does not extend as far as the east county line. The oyster, Exogyra ponderosa, is found in clays resembling the Taylor on the slope to the alluvial plain of the Cibolo on the Nacogdoches road about 15 miles from San Antonio. In the western part of San Antonio are seen several exposures which are referred more or less definitely to the Taylor forma­tion. One of these is seen in the cut on the Fredericksburg road at the crossing of a small stream about two miles from the Court­house. Another is seen at the Culebra Road crossing of the same stream a little farther south. In neither of these exposures are fossils found and the reference to the Taylor formation is on the lithology. A similar exposure of yellow clay is seen on the same creek still further south, at the crossing of the old Castroville Road near its union with Zalzamora Street. The southernmost belt of Taylor exposures in this county is that which extends from San Anotnio northeastward to the county line. Exposures of the Taylor of this area may be seen at a cut in the public road on River Avenue, at the north city limits, and again on the Austin road opposite the Aviation Post about 6 miles from San Antonio. At neither of these exposures so far as observed are fossils found and the identification is chiefly on lithologic characters. The belt of the Taylor marls is here narrow as the Austin formation is exposed a short dis­tance to the north, while fossils indicating the Navarro are found not far to the south of these localities. To the east of Salado Creek the Taylor formation lies south of and approxi­mately parallel to the Austin road, to the county line. Geology and Mineral Resources of Bexar County llAVABBO POBllU.~011 The Navarro formation includes chiefly deposits of clay and marl although in parts of the formation, particularly toward the upper limits, there are layers of well indurated lime rocks and in places limestone ledges. Lithologically the formation on sur­face exposures resembles the Taylor. In the Navarro, however, is found considerable glauconite which is frequently in such abundance as to give a greenish tinge to the clays and shales of the formation. Within the formation, probably in its upper part, is a green glauconitic sandstone, often met with in drilling anWAY The Midway formation of this county includes chiefly arenaceous clays in which are imbedded many concretions of sandy or limy rocks. The concretions are of various sizes from small concretions weighing only a few pounds, to those of large size, making up masses of rock of several tons weight. Thickness : The most reliable measurement of the thickness of the Midway formation obtained is that from the Mathey well drilled in 1919 near Losoya. The following data on this well have been kindly supplied by Messrs. H. L. Hamilton and W. L. Walker. STitATIGRAPHIC DATA FORM MATHEY WELL LOSOYA, TEXAS Horizon. Lignite cuttings at 367, 560 and 590 feet Wilcox. First fossils recovered, f.rom cuttings, at 665-670 feet were: •volutilithes limopsis Conrad Midway. Olivella mediavia Midway. Fossils found in core sample from 927 to 928 feet: Linthia alabamensis Clark Midway. Pecten alabamensis Midway. Fossil from cuttings, 1070-10!.IO feet: Cerithium mediaviae Midway. Fossils from cuttings at 1110, 1135, 1170, 1195, 1270 and 1340 feet all were characteristic Midway forms except a few that carry through to Cretaceous. Fossils f>rom a core sample 1402-1406 feet, were the first to definitely establish the Cretaceous: Ammonite Cretaceous. Cuspidaria Cretaceous. •All fossil identifications were checked by Dr. J. P. Smith. Geology and Mineral Resources of Bexar County The top of the Midway horizon is somewhere between 590 and 665 feet deep. The bottom is between 1340 and 1402 feet. While there is no lithological suggestion of lower contact, it would ap­pear that the upper contact lies close to the 600-foot level. From these determinations it appears that the Midway at this place has a thickness of between 675 and 810 feet, and that the Midway and Wilcox have a combined thickness of between 1340 and 1402 feet. The record of a second well showing a great thickness of the Tertiary, the Sarah Smith No. 1 of W. C. Steubing, the data for which has been supplied by the United States Geological Survey1 is given in the chapter on well records. Physiograhpic expression: The belt of country occupied by the Midway formation is for the most part moderately hilly, the hills having as a rule a southward slope which possibly in, many instances approximates a dip slope. The soils derived from the formation are dark or brown in color and are more sandy than are the soils of the Cretaceous although less sandy than the soils of the Wilcox formation. The prevailing timber grown on the Midway hills is mesquite. Common fossils: Marine fossils are found in the Midway although rarely abundant. Of the mollusks the genus Veneri­cardia is the most abundantly represented. Surface exposures and local details: The Midway formation is well exposed in the cut made by the Missouri, Kansas and Texas Railway in the southeastern part of San Antonio. On fresh exposures the clays of the Midway at this cut are massive, much jointed and of medium hardness. On exposure they crumble to very small particles. The clays include numerous oval or flattened small concretions, frequently hollow, or con­taining hematite or other minerals. Veneric,ardia was obtained from this section by Stephenson. (Mss. Notes). The following notes have been made by Mr. Baker, who :first examined this exposure and recognized it as of the Midway formation: 'Ilhe Midway clays beneath the Uvalde in the new "Katy" · cut through the hill in the eastern part of San Antonio are not ap­preciably sandy but are more weathered than in the lower-lying exposures of lower horizons. This weathering was to some extent University of Texas Bulletin at least accomplished in pre-Uvalde times. The clays are irregu­larly mottled yiellowish-brown and light olive green with thin films of dendritic manganese oxide on joint planes, and an occasional small white nodule or concretion of CaCO,. The clays are much jointed. Among other exposures of the Midway noted by Baker are the following : Greenish drab unctuous clay, weathering yellow-brown with a few r.ed limonite sandy concretions and carrying Venericardia planicosta and a few other fossils as casts, is found in the gully east of ridge just below the junction of Salado and Rosilla creeks. In this gully are seen also the large yellow brown concretions, some of them with cone-in-cone structure. The Midway apparently ca-rries marine fossils to its very top. Thus the highest beds a mile above the mouth of Comanche Creek (south of Alta Vista oil field) carrying the unctuous clay casts of Venericardia alticostata and other fossils. As usual the Midw:iy here carries the brown limestone concretions. In the Alta Vista oil field very large concretions are exposed at the surface which with little doubt are Tertiary and prob­ably of the Midway formation. At the crossing of the Gal­veston, Houston and San Antonio Railway on Rosilla Creek, east of San Antonio, exposures of the Midway clays are seen both in the stream bed and in the railway cut. In the dump from dug wells near this crossing were seen the massive clays of this formation, including numerous small concretions identi­cal with those of the Midway at the Missouri, Kansas and Texas Railyaw cut in San Antonio. On the Medina River exposures recognized as Midway are found as far downstream as the Palo Alto Road crossing. The following section at this crossing is from notes made by Steph­enson:­ Section in ravine near north end of bridge over Medina River, Palo Alto road: Feet Terrace deposit: 1. Yellowish sandy loam . . .... .. ....... .. . . . 18 2. Bed of coarse gravel . . . . . . . . . . . . . . . . . . . . . 2 Eocene (Midway): Geolo!TY and Mineral Resources of Bexar County 3. Hard, gray, earthy sandstone streaked with reddish limonitic iron ore. Shows faint cone-in-cone structure in the more earthy streaks . . . . . . . . . . . . . . . . . . . . . . 1 4. Dark gray, fineiy sandy, shaly clay ..........18 5. Ferruginous layer of fine earthy concretion­ary sandstone with some concretionary masses of hard limestone in center. Faint cone-in-cone structure noted in the more earthy portions. A few faint fossil impressions. Probably same as layer at bottom of bluff below Garza crossing ... .. . .... ............ . . . .. 1-2 6. Dark gray, finely sandy, shaly clay .. ... ......2 7. Concealed to water .. .... ... ......... . ... 15 ± The lowest layer in the prEceding section dips down to water­level within about 200 yards below the bridge. WILCOX l"OBMA.TIO:N The Wilcox formation is well developed in this county and includes thinly laminated sands, sandstones, sand and limestone concretions, clays and lignites. The presence of sea shells in­dicates the marine origin of parts of the formation, while the lignite and land plants preserved in some of the shale indicate the lacustrine or near-shore origin of parts of the formation. Thickness: No data is at hand at present by which to approx­imately determine the thickness of this formation in Bexar County. A well drilled near the south county line at Saspamco starting at or near the top of the Wilcox, extended to a depth of 2500 feet. This well with little doubt passes through both the Wilcox and Midway and into the Cretaceous, but it is not possible from the log to determine the limitations of the sev­eral formations. A well drilled on the J. K. Lamb property in the southern part of the county starts near the top of the Wilcox. In this well the Eagleford formation, according to examination of the samples made by Dr. J. A. Udden, was probably reached at about 1900 feet (Mss. notes). Allowing for the Cretaceous, overlying the Eagleford, its usual thickness of about 1200 or 1300 feet, there remain 600 or 700 feet to be assigned to the Wilcox and Midway formations. Physiographic expression: The soils derived from the Wilcox formation are sandy and frequently of a red color. The coun­ University of Texas Bulletin try underlain by the formation becomes somewhat hilly and rough by the development of stream channels and valleys. The timber growth is mesquite in part, although deciduous oaks and other hardwood trees are found on the more sandy lands. Common fossils: The fossils of the Wilcox formation of this county as already indicated are in part marine invertebrates and land plants. Surface exposures and local details: In the bluffs west of the Pearsall Road crossing on the Medina River are numerous heavy limestone concretions. The cut made for the public road on this bluff exposes thinly laminated sands carrying plant fragments. These sands and concretionary limestones appear to represent the Wilcox formation. Similar laminated sands including limestone concretions are seen in he bluffs in the vicinity of Van Ormy. Good exposures of these sands are seen on the St. Anthony farm about three-fourths of a mile south of Van Ormy. Sandy lime concretions are seen here which measure as much as 35 feet in length by 15 feet in width and 8 feet or more in thickness. They are imbedded, finely­laminated, clayey sands. On the Gonzales Road, laminated micaceous sands of the Wil~ox formation are seen on the slope to Saunders Creek, 131;2 miles east of San Antonio and thence in numerous ex­posures to the east county line. At the intersection of the Gonzales and Prie Roads about 17 miles from San Antonio, the dump from a dug well was found to contain typical sandy clays of the Wilcox formation including a few well preserved leaves. Thin lignite beds are reported in well logs of this part of the county. Much of the field work on the Wi1cox formation in Bexar County was done by Mr. Baker, from whose notes the following observations are taken: On Losoya Creek, at concrete bridge on the Corpus Christi Road, the strata dip 3° S 60° E, which may not be the true dip. At tbe base of the section are thin alternating beds of loose brown sands and laminated clays overlain by brown, much cross-bedded sand­stone 3 feet. above which is mainly laminated sandy clay about 20 feet. The bottom of a small syncline is seen at the bTidge, the axis Geology and Mineral Resources of Bexar County 5!J of which trends northeast-southwest. The dip on the northwest limb runs up to 10° or more, but flattens rapidly. A splendid section of the Wilcox is exposed at the jog in the public road about three miles north of Elmendorf. The section is as follows: Brownish stained sands, weathering into "bad lands" . . . . . . . . . . . . . . . . . . . . . . . . 8 Laminated gray, medium-grained sands, weathering light brown with some thin interlaminae of yellow-brown clay ......15 Gray drab, unctuous, structureless fire clay, passing downward into chocolate carbonaceous shale and finally into a good grade of lignite. The lignite has a minimum thickness of 2 feet with the base not exposed ... .. ............... 6 Slightly laminated brownish-gray medium­ grained micaceous sand with large flat­ tened elliptical sandstone concretions at top and bottom .............. . ... 10 The observed dip in a direction about 20° south of east, ap­peared to be 7°, but flattened out toward the south. The lower Wilcox on Medina River at southern boundary of San Antonio topographic sheet, west-southwest of Earle, consists of medium-grained gray cross-bedded sands, with large sandstone con­cretions, weathering brown. In the bed of Comanche Creek a short distance above its junction with Leon Creek are many very large flattened sandstone concretions. Associated with these are inter­bedded brown sands and shaly gray sandy clay. The lower Wilcox at the bridge over Six Mile Creek, where crossed by old Espada Mission ditch, is medium-grained gray sandstone, somewhat cross­bedded, weathering brown and locally cemented into sandstone. Near mouth of first tributary on the west side of Calaveras Creek south of crossing of road running east-northeast of Elmendorf, are black and brown layers carrying carbonaceous materials in brown­ish laminated sands, with alum incrustations. Most of the 10-foot section is fine sand, some layers with an admixture of clay. The apparent dip here, possibly due to slumping, is about 50 to the east. Large ripple-marked fl.at blocks Of brown sandstone occur in Cal­averas Creek bed in this locality. The sands are laminated and when fresh are light gray in color but are often stained with limonite. The Wilcox soils are light brick red and generally sandy. The sandstone layers in the Wilcox here are often cross-bedded and ripple-marked. W•hen fresh, the sandstone is gray in color, but oxidation of the iron gives the brown most generally seen. Locally University of Texas Bulletin they may be almost as hard as quartzite but they seem to be almost, if not quite, always local indurations of a concrelionary nature. At one place on Calaveras Creek about half a mile below the bridge before noted, ripple-marked and cross-bedded sandstone about 3 feet in thickness overlies large flattish concret.ionary masses cementing a conglomerate of light brown clay balls. Some have septarian structure and are seamed with crystalline calcite and cone-in-cone structure. These concretions contain marine Eocene fossils, carbonaceous fragments and grains of glauconite. In all respects they resemble the Wilcox concretions in Sabine-town bluff, this being the first locality of marine Wilcox found west of the Sabine basin. The concretionary layer is only about 4 feet above the bed of the creek. Below are 4 to 5 feet of loose laminated sands and above the ·sandstone layer overlying the concretions are about 20 feet of laminated gray clayey sands, limonite-stained and locally cemented. The latter are found in the bluff about 200 feet to the westward. The sandstone blocks between here and the b:ridge evidently belong to the same stratum, the one over the fossil-bearing concretions, only one large fossiliferous concretion being known to occur here. Nearly half a mile farther down is another 20 foot exposure of ·wilcox. Here is about 5 feet of lavender carbonaceous sandy and unctuous clays at base, succeeded by cross-bedded, laminated sands with occasional thin laminae of clayey material for the next 10 feet. 'fhe upper five feet consists of two one-foot beds of gray clayey laminated sands separated and overlain by cros&-bedded brown sands, the upper 2 feet of which is more consolidated and consists of a conglomeratic sandstone with small clay-iron-stone pebbles and small sharks' teeth. This sandstone is also ripple-marked. Peb­bles of clay-iron-stone in such a formation mean little, for they are soon formed in consolidated condition along st'ream banks and ocean or lake littoral deposits. From this point on downstream to below the steel wagon bridge at Saspamco the banks sometimes 30 feet high are composed of alluvium of clayiey sand. The first section on Parita Creek, 1h mile above mouth, shows at base 6 feet of lavender, carbonaceous, cross-bedded, laminated, sandy clay, dipping upstream at an angle of about 10 °, succeeded above by about 6 feet of laminated sand and being nearly horizon-· tal. The whole section is prevailingly sandy, with indu·rated sand­stone layers both above and below. The first exposure on Parita Creek south of the bridge, about 4 miles northeast of Elmendorf (about 1-5 mile south. of bridge) shows 9 feet of thinly interlaminated clay and sand layers. The sand layers are genP.rally thicker than the clay layers, but few of the formeT are much thicker than an inch. The sand is brown, weathering gray when fresh. The clay laminae are gray when dry Geology and Mineral Resources of Bexar Co·unty 61 and lavender or light chocolate when wet. Sand is fine-grained and micac€ous and some layers are 2 to 3 inches thick. The .next three exposures downstream show substantially the same. The in­terbedding of sand and clay laminae still continues. Either one may sometimes be extremely thin, sometimes not much thicker than bristol board or thin cardboard. Light exposure about 1 mile be­low bridge shows above 10 feet of laminated, brown, fine~grained sands, with nodules arranged in thin layers of a whitish powdery substance, probably CaC03• Below is 10 feet of mainly light gray, thinly-laminated, sandy clay but containing one 21h 11 layer of sand 21h feet above base. The clay member has three interlaminae of sand as was noted farther upstream. This exposure at junction of east tributary. One-half mile downstream below last 3 feet of rusty brown ripple and rill-marked irregular-bedded sandstone over­lies unconsolidated sands with interbedded laminae of clay. The next exposure downstream shows a good deal of cone-in-cone struc­ture in brown sandstone concretionary layers, interbedded with clayey sands. On Calaveras Creek, about 21h miles northeast of Elmendorf, and of Parita Creek, near the Bexar-Wilson county line, about 1h mile north of southermost of two main road crossings in a northeasterly direction from Elmendorf, is exposed about 10 feet of light brown laminated sands. Next exposure, a mile farther upstream, has the usual interlaminated sands and clays with flattish sandstone con­cretions and selenite crystals 10 feet thick. Also a 7-foot exposure of the latter on road just east of bridge over Calaveras Creek 3 miles northeast of Elmendorf. The first exposure of any moment on the largest eastern tributary of Parita Creek, near the Bexar-Wilson county line, about 1h mile above mouth of creek, consists of about 5 feet of thinly-laminated light chocolate clay, with very thin partings of light gray mica­ceous sand; above is 7 feet of thinly-laminated light gray clayey sand, seamed with limonite, and becoming sandier and less lami­nated in the upper 21h feet; capped by 8 feet of light gray, fine­grained sand weathering light brown with thin beds, especially at the top, of a white kaolin-appearing substance. The basal clays contain carbonaceous remains. The next exposure, at least 3/4 mile farther upstream, consists of the same sort of materials as the last and a recent well dug in the creek bed between the two shows about 10 feet of gray micaceous sandy clays and clayey sands. Under the last exposure noted lie brown concretionary sandstones some with cone-in-cone structure. These concretionary laye·rs, as usual, are ripple-marked. Some of them are large flattened discs, gray in color when fresh, and hard as quartzite. The concretionary layers are interbedded with the usual clayey sands, which are lami­nated. Some of its larger concretions are probably cemented with sphaero-siderite. A conglomeratic concretionary layer, found at least Univerrmty of Texas Bulletin 1 lf.i miles upstream from the mouth of the largest eastern tribu­tary of Parita Creek, was composed of rolled iron-stone pebbles, shark's teeth and oyster fragments. The latter may have come from the Cretaceous. Also worn fragments of other shells. As one goes upstream and consequently into lower strata, the beds become more clayey, becoming gray drab stained with oxide of manganese, and with small whitish soft, perhaps calcareous concretions. The following notes on the Wilcox and other Cenozoic for­mations in Bexar County have been contributed by Dr. L. W. Stephenson : Medina River, a ·few hundred yards below the crossing of the Corpus Christi Road near Losoya, Bexar County, Texas, 13 % miles south of the San Antonio postoffice building. Section Feet Pleistocene: 2. Massive brown loam, becoming sandy and pebbly toward base and locally a basal bed of gravel reaching 3 or 4 feet in thickness. The material stands up in a vertical wall along the bluff like loess. 20-35 (Profound unconformity) Eocene (Wilcox?): 1. Gray to greenish gray, cross-bedded sand and sandstone. The sandstone consti­tutes local indurations of the sand. It is sofit; to very hard and is poorly ex­posed along the base of the bluff which is covered with talus .... . .........15-30 Faint banding is noticeable in layer No. 2, and about 10 feet below the top is a distinctly lighter band having a yellowish color. The bluff extends for several hundred yards along the left bank. Earle, Texas, 11 ~ miles due south of the San Antonio postoffice building. At the head of a gully on the east side of the road and south of Medina River, sandstone has been quarried for use in concrete work at the new bridge at Earle. The rock is the indurated. portion of a greenish gray, cross­bedded, rather fine sand formation. It is not very well exposed, the slopes being covered with vegetation and rock debris. Unin­durated portions of the sand are exposed in the head of the gully PrO'Iler. Thirty-five or forty feet of the rock and the unconsolidated Geology and Mineral Resources of Bexar County sand is exposed. The rock rises nearly to the surface of the sur­rounding upland. Down the gully the rock and sand are overlain by Pleistocene sandy loam which rests unconformably against it. The sandstone contains large numbers of fossil leaves well preserved. As the rock does not split well the leaves are hard to get out in perfect condition. (Collection No. 181). I was informed of the where­abouts of the fossil plant locality just described by Mr. T. B. Apple­white, whose address is R. F . D. No. 7, Box 33, San Antonio,. Texas. (The fossil leaves from this locality have been described by E. W. Berry' in Prof. Paper 91, pp. 8-20, pis. 1-3, 1916). Corpus Christi Road, crossing of Losoya Creek, half a mile south of Medina River crossing. Section Feet Surficial-alluvium: Reddish brown sandy loam with accumula­tion of pebbles at base in places. Con­tains land shells ................... 4-15 (Great unconformity) Eocene (Wilcox?): Laminated, finely sandY1 gray clay, and part­ings and thin layers of gray to brown­ish fine sand, some layers 6 or 8 inches thick. Some vegetable particles. Max .. 20 Layer of ferruginous earthy sandy lime­stone, apparently of concretionary· origin, cemented, on top of which is a thin conglomeratic layer composed of coarse pebbles, most of which appear to be fine ferruginous sandstone and sandy i r o n carbonate concretions. Among those pebbles were collected a few poor prints of Venericardia. Also some silicified wood. . . . . . . . . . . . . . . . . . 1 Irregularly bedded sandstone and loose sand, some showing ripple marks, with subordinate gray laminated clay. . . . . . . . 4 c.a.:amzo roBMA'l'X01' The Carrizo sandstone was named and described by Owen in the First Report of Progress of the Texas Geological Survey, published in 1889. The Carrizo formation of the Cambrian system exposed in the Carrizo Mountains of the Van Horn UniveJrsity of Texas Bulletin Quadrangle, was named by Von Streeruwitz in 1891.* If, tl1ere­fore, the Carrizo of the Eocene is recognized as of formation rank, the name as applied to this sandstone takes precedence over the Carrizo formation of the Cambrian. The Queen City member of the Wilcox formation, which is usually regarded as the northeast Texas equivalent of the Carrizo sandstone, was named by Kennedy in 1896.t The Carrizo sandstone is re­garded by some as a member of the Wilcox formation. A belt of sand hills extends across the southernmost part of Bexar County, representing "Country underlain either by the Carrizo sandstone or by very sandy phases of the Wilcox. This area is referred to locally as the "sand hills". The approximate location of this belt of country is indicated on the map. Some of the hills near the county line in the southwestern part of the county, thickly strewn with concretionary ironstone fragments, may represent outliers from the Mt. Selman forma­tion. PLEISTOCENE No marine formations are found in this county of later date than the Eocene period, the late Cenozoic being represented only by non-marine deposits, including river flood-plain, and to some extent chemically formed, sediments. Presumably, as indicated by the absence of marine formation, this area has been subjected to surface erosion during the latter part of the Tertiary and all of the Pleistocene. In this long interval there has been formed a complicated and extensive series of river flood plains. The earliest or oldest of these have themselves been more or less com­ pl~tely destroyed and removed by erosion. Of those that remain some are as old as the early Pleistocene, or possibly older, while others were formed during the middle and latter part of the Pleistocene period. For a part only of this county are topographic maps available, and it has not been practicaible to make a detailed study of the successive flood plains. It is important, however, to indicate *Second Annual report of the Geol. Surv. of Texas, p. 683, 1890. tThe Eocene Tertiary of Texas east of the Brazos River. By Wm. Kennedy. Proc. Acad. Nat. Sci. Phila. for 1895, p. 135, 1896. Geology and Mineral Resources of Bexar County the general characteristics of the flood plain deposits, and to map the laTger areas. The flood-plain deposits of the county may be divided into two main groups, each of which is distinctive. The first of these groups includes the older and hence higher terraces of the county which are not obviously associated with the existing streams. The second group includes the low or late terraces whose rela­tion to existing streams is sufficiently evident. Data on which t<> determine the age of the older terraces are wanting, but they may safely be placed as early Pleistocene or older. The late terraces are recognized as belonging to the latter part of the Pleistocene period. The older and higher flood-plains, of which there are at least two and probably several, have some characteristics in common. As already stated they are not obviously associated with the existing streams. The sediments of these older terraces are locally more or less firmly cemented by calcium carbonate thus differing from the materials of the recent terraces, which are largely uncem1;mted. Paleontologically, the older terraces pre­sent the negative characters of a complete or almost complete absence of fossils, while the more recent terraces contain fresh water land snails and in places vertebrate remains. Concretion­ary or pisolitic calcium carbonate pebbles subsequently more fully described, are occasionally found in the older flood-plains and in places are abundant, making up locally the greater part or all of the formation. 'UVALDE E'OBlllATJ:Ollr AlfD 'UVALDE PL.a.Dr (Pliocene or Pleistocene) The oldest and highest flood plain deposits of this area are proba"bly contemporaneous in age with those which have else­where been referred to the Uvalde formation. The materials of this formation as developed in Bexar County include limestone and flint boulders often imbedded in a softer matrix of finer material, clay or silt, or in some instances soft calcareous ma­terial resembling caliche. Approaching the Balcones Escarp­ment, the limestone boulders, as would be expected, increase both in relative abundance and in size. Southward from this escarp­ 5-Bex. University of Texas Bulletin ment the relative amount of fl.int pebbles, although of smaller size, are in pr0portionately greater abundance. Th'e flints of this formation were derived largely from the Edwards forma­tion The foncstone boulders came originally from this or from other limm;tonc formations, having been moved in many in­stances proba.bly no great distance. Well to the south where this flood plain overlies Upper Cretaceous formations, there are undoubtedly exteneive inclusions from these formations. Un­der these con the Uvalde may contain beds of clay arnl mnrly ,(eposits whirh are with difficulty separated from the im­mediately underlying Upper Cretaceous formations. Mally of the fl.int pebbles of this formation are coated with calcium car­bonate. The amount of this coating varies from mere films surrounding JaJ'ge flints to calcium carbonate concretionq oi varying sizes awund fragments of flints as a nucleus. 'l'hese concretions me more fully described subsequently. The gradient (Jf the streams bein~ reduced in passing coastward from the hills, the coarse ID:!teriflls of all these flood plains grade to finE' silts and loams which are non-resistant to erosion and are finally lost. The gravels of the Uvalde formation are utilized in road building and for concrete. Tkickness: The Uvalde plain, being the oldest of the flood plains of this area, has been cut into and largely destroyed by erosion, and hence persists as hardly more than a remnant of its former extent. In thickness the formation probably varied greatly depending upon the irregularities of the top surface of the underlying formations. In those areas where the formation now persists there is observed a thickness varying from a few feet to as much probably as 70 feet, although more commonly the gravels of this formation are between 15 and 30 feet in thickness. Surrface exposures and local detail6: Originally the Uvalde flood plain must have occupied an extensive area immediately south of the Balcones Escarpment, grading from very coarse materials near the hills to silts and loams farther south. The softer materials of the formation probably were first removed by erosion, the gravels and heavy conglomerates having been more persistent. Some of the areas occupied by this formation are indicated on the map, although for reasons elsewhere stated it has Geology and Mineral Resources of Bexar County not been possible to represent all of the flood plains deposits of the county. The range of Austin Hills crossed on the F.redericksburg Road eight miles from San Antonio are overlaid by a remnant of the T.Tvalde formation. The formation is well exposed on this road 7.8 miles from San Antonio, where it consists of flint and hard limestone gravel imbedded in a chalky matrix. In a cut on the Altgelt-Wurtzbach road near its union with the Fred­ericksburg Road, 8.7 miles from San Antonio, is another good exposure of the formation. The lower part of the exposure here is chiefly very soft white marly material overlain by about eight feet of gravel including some very heavy limestone boulders. This. area of the Uvalde formation continues with some interrup­tions as far to the southeast as the Waring estate between the Bandera and Culebra roads. The elevation of these exposures varies from about 1010 feet at the Fredericksburg Road crossing to 850 or 900 feet at the Waring estate. No fossils are known from the Uvalde gravels except possibly some invertebrates that have washed into the formation from the older formations. Ph;ysiographic expression: The Uvalde formation makes a plain now much cut into by erosion. The slope of this plain is more pronounced than that of the next later plain. Thus the Uvalde plain, if correctly identified, slopes south at the rate of about 20 feet per mile, while the lower plain on which Kelly field is located, slopes south at about 15 feet per mile. Locally the materials of this formation have become firmly cemented forming hard calcareous rocks. Under these conditions rocky thin soils are found, clothed with a mixed vegetation, chiefly oaks; more commonly, especially toward the southern part of the area, occupied by the formation, the soils are very gravelly and the prevailing timber growth is mesquite. Surface exposures and 'Weal details: On the west side of Leon Creek west of San Antonio is found a considerable remnant of a flood plain which may be either an extension of the Uvalde plain or probaibly may be a plain at a slightly lower level. The plain here lies at the Castroville road crossing at an elevation of from 750 to 800 feet above sea level. To the south this plain Univ·ersity of Texas Bulletin may be recognized to about the Frio Road crossing where it terminates by surface erosion although probably remnants may be found somewhat farther south. The plain may be traced to the north where it seems to pass without any very appreciable break onto the plain adjacent to Gulebra Creek. On the up­lands between Medio and Potranca creeks are terrace plain rem­nants which apparently lie at about the same level, and origi­ nally perhaps were parts of the same plain. At the north side of the Castroville Road, about one-fourth mile beyond Leon Creek, deep gullies have washed into the gravel beds of this plain, affording a good exposure. The formation here rests on the Navarro and the lower three feet in this exposure consists of a very heavy pebble conglomerate in which are found large masses of glauconitic sandstone de­rived from the Navarro formation. These green sandstones of the. Navarro are now exposed as elsewhere noted in the same bluff. Above this level is seen white marly material. Near the top of the exposure pebble beds again come into the section. An exposure of gravel which is probably to be referred to the Uvalde formation is seen in a cut in the public road on New Braunfels Avenue, about 0.7 mile north of the north city limits of San Antonio. In this cut there are exposed about ten feet of clay, white chalky marl, and gravel. The gravel beds are strongly cross-bedded. The clay of this exposure, although probably included within the gravel series, closely resembles the clay of the Taylor formation which is exposed on River Avenue nearby. Similar gravel beds underlie the high lands north and northeast of Alamo Heights, lying at elevations of from 750 to 800 feet. Heavy gravel deposits overlie the highlands in the north­eastern part of the city of San Antonio and are well exposed in the cut made by the Missouri, Kansas and Texas Railway as well as in pits opened up for road material. The gravel beds at this exposure rest upon the Midway clays and are variable in thickness from a few feet to a maximum of 25 feet. The upper 3 or 4 feet are in places caliche cemented and form a very hard rock. At lower levels the gravel is less firmly cemented and is frequently cross-bedded. Lenses of clay like­ Geology and Mineral Resources of Bexar County wise are observed, one of which is a foot thick and 50 or 60 feet in lateral extent. Many of the flints are coated with a thin covering of calcium carbonate; on some of the flints, especially the smaller ones, this coating is thicker and shows concentric or concretionary layers. Concretions consisting wholly of calcium carbonate, or with merely a nucleus of flint or other material, are present in this exposure, although not particularly abundant. In a pit opened for road material on the Sulphur Springs R-0ad near tills cut, the deposit consists almost who!ly of small calcareous concretions. These are more fully described later in connection with the description of similar concretions from other localities. LEONA (?) l'O:BMATION AND l'LAIN (l\Iid-Pleistocene?) The term Leona was proposed in 1900 by Dr. T. \V. Vaughan, and was applied to a well dewloped flood plain in the Uvalde quadrangle lying at a lower level than the Uvalde plain* In Bexar County there is a well developed flood plain which very possibly is contemporaneous in time with the flood plain to which the name Leona has been applied, and which is there­fore tentatively correlated "·ith that formation. In Uvalde County, according to Vaughan, the position of the Leona formation is intermediate between that of the present ffood pluin and the Uvalde plain. In Bexar County the conditions are more complicated, in that there are three Pleistocene flood plains, the Leona being intermediate between the older and the younger. The relation of the Leona flood plain to the existing streams is perhaps less obvious in Bexar than in Uvalde County. However, the writer offers the tentative suggestion that this flood plain as developed on the broad plains on which Kelly Field is located, is associated with the Leon Creek drainage. In the chapter on structure it is shown that the plunge of the structures underlying this area is to the southwest. Leon Creek in cutting across these structures has therefore tended to shift its course to the southwest. The effect of the south­ ----.-U. S. Geol. Surv., Uvalde Folio, p. 3, 1900. University of Texas Bulletin west shifting is seen at the present time in the high bluffs of this creek all of which in this part of its course are found at the right, or southwest, side of the stream. The tentative explana­tion offered is that the Kelly Field plain as now developed was built up chiefly by Leon Creek or its predecessor which has gradually shifted and is still shifting its course in a south­westward direction. The plain east of San Antonio may in the same way be associated with the Salado C'reek drainage. 'rhe high bluffs of the Salado, like those of the Leon, are on the right bank, the plain being entirely to the east of the stream. That the San Antonio River has taken so small a part in the development of this plain may be explained by the fact that its drainage system scarcely extends back to the Balcones escarpment and the flood waters which it carries are less ef­fective than are those of some of its tributaries. The materials of this formation are extensively used for road building. Water is obtained from the gravel beds of the forma­tion, chiefly through shallow dug wells. At the Castroville Road crossing on Leon Creek this plain stands at a level of from 700 to 710 feet above sea, or from 50 to 100 feet below the level of the plain on the west side of Leon Creek already described. The slope of the plain is to the south or southeast and amounts to between ten and fifteen feet per mile. Its southern margin on the Somerset and Corpus Christi roads, six or seven miles south of San Antonio, ap­proximates six hundred feet above sea level. The part of this plain lying to the east of Salado Creek has a slope from north to south amounting to an average of about 15 feet per mile. The materials of this plain are largely gravel, and loam, although over a considerable area adjacent to the San Antonfo River and Salado Creek, the deposits consist largely of con­cretionary calcite pebbles. At an excavation on the Quintana Road, 7 miles southwest of San Antonio, there is exposed of the formation 15 or 18 feet. The materials of the formation as seen in this exposure are stratified and consist of alternating layers of heavy gravel and calcareous sand. The deposits are here sufficiently well indurated to require blasting in working. Thickness: Numerous pits for road material have been opened into gravel deposits of this plain. In these pits the Geology and Mineral Resources of Bexar County formation as a rule has a thickness of from 20 to 30 feet. In some of the wells dug into these gravels they have been found to be from 40 to 45 feet thick. Since the gravel rests upon an eroded surface of the Upper Cretaceous and Tertiary forma­tions, they may be expected to vary greatly in thickness from place to place. Physiographic expression: The plain formed by these deposits has a very gradual south or southeast slope amounting on an average to about fifteen feet per mile. The soils include gravels and loams. The vegetation on the uncleared lands is chiefly mesquite. The elevation of this plain at its northern limit is about 750 feet while its gradual slope carries it to a level of about 650 or 600 feet at its southern limits. Common fossils: No fossils have been found by the writer in this formation, although the presence of vertebrates, particu­larly large proboscidians, has been reported from excavations within the city of San Antonio. Inasmuch, however, as the locality in question is near the headwaters of the San Antonio River where this plain merges with the later Pleistocene alluvial plain, an exact record of the fossils in the excavation is necessary in order to make sure of their place in this formation. In the absence of fossils the plain is referred doubt­fully to about the middle part of the Pleistocene period. This reference is based on the fact that this plain lies above the late Pleistocene plain, to be described, and on the fact that the materials of the formation are not infrequently quite well cemented. Awaiting a more detailed study of these deposits, or the discovery of indigenous fossils, the age of the formation can scarcely be more accurately determined. Surface exposures and local details: The largest continuous development of this plain is that extending from Leon Creek to the San Antonio River. The northern margin of this plain is found at the foot of the hills of the Austin and Taylor formations near or south of the Culebra Road. At its southern margin the plain terminates probably by surfac·e erosion some six or seven miles south of San Antonio, although near the San Antonio River remnants of the plain, too limited to map, are found several miles forther to the south. Another large development of this plain is that found east of Salado Creek University of Texas B'ldletin and extending from just south of the Austin Road crossing to about the Goliad Road crossing. Good exposures of the gravels of this plain are afforded in the pits opened for road materials. In these pits the gravels are seen to be irregularly stratified or cross-bedded, often with alter­nated bands of coarser and finer materials. Most of the gravel is flint, although in this plain, as in the higher Uvalde plain, there are local areas in which the materials are made up en­tirely of small calcium carbonate concretions. On this plain such concretions are seen in numerous pits on the west side of the San Antonio River and on the east side of the Salado River. In the valley of the San Antonio River this plain apparently merges into the late Pleistocene and recent plains within the city of San Antonio. The concretionary gravels are subse­quently described. LATE PLEXSTOCEliE AL:LUVXAL DEPORTS The flood plains here regarded as of late Pleistocene age are those which border on, and have an obvious relation to, the existing streams and which lie above the present flood plain. The most pronounced development of the plains of this kind are those of the Medina River. The inorganic materials of this plain are chiefly silts and loams. The maximum width of this late Pleistocene plain is found on the Medina west of the central part of the county where that river lies near the boundary between the Cretaceous and Tertiary deposits. Farther to the east where the river is cutting through the Tertiary formations, the plain, although conspicuous, is not as a rule so wide. The next best development of this plain is that which borders Salado Creek. Here also the maximum width of the plain is found where the creek is cutting through the soft upper Cretaceous formations, the Taylor and Navarro. In the Ter­tiary formations the plain is noticeably narrowed. On the San Antonio River there is but a slight development of this plain. Thickness: The late Pleistocene flood plain deposits attain a maximum thickness on the Medina River of about 50 feet. On the smaller streams they are of lesser development. Physiograplvi,c expression: The late Pleistocene plains are seemingly very level, although as a matter of fact they slope Univ. of Texas Bull. 1932. PL I Pisolitic gravel in the Pleistocene as seen in pit excavated for road material near the Mission Loop Road south of San Antonio (See page 75). Geology and Mineral Resources of Bexar County very gradually downstream, the rate of slope amounting to about 15 feet per mile. The soils are calcareous loams, and the timber growth includes considerable hardwood deciduous trees. Common fossils: The late Pleistocene and the Recent deposits of this area are characterized by an abundance of the small land snail, Bulimulus dealbatus mooreanus• which is common throughout this region at the present time. The presence of this snail in the late Pleistocene deposits and its absence so far as observed in the older formations, suggests changed climatic or environmental conditions in the late Pleistocene. In addition to the land snails, proboscidian remains have been found in this formation at a number of localities. From the lower plain on the east side of Salado Creek, Baker secured the tooth of a mammoth, Elephas (Mss. notes). From the loam deposits at the Frio Road crossing on Medina River, Mr. C. H. Vogt collected some years ago a number of teeth of the elephant together with other large bones probably of the same animal. Surface exposures and local details: The exposures of this late Pleistocene plain are found bordering all the larger streams lying from 25 to 35 feet above the present flood plain. The formation is readily recognized where typically developed by the presence of calcareous loams, containing a great abundance of the small land snail. In mapping, it has not been practicable on the scale used to represent this formation on the smaller streams, nor to show its full extent upstream. In all cases, however, it narrows in width and approaches and gradually merges into the present flood plain. Probably the maximum thickness of the formation is seen on the Medina River near the Pleasanton Road crossing, where typical exposures are seen. CAVE DEPOSITS Numerous caves exist in the Cretaceous and Comanchean limestones of this county. One of these caves on the property of Mr. A. Friesenhahn, about 20 miles north of San Antonio, has been found to contain vertebrate fossils. The presence of *Kindly identified from Bexar County specimens by Dr. Paul Bartch. University of Texas Bulletin fossils in this cave was discovered some years ago and a small amount of collecting from the cave has been done by those locally interested. The entrance to this cave at the present time is through an opening extending vertically downward for about 25 feet. Formerly, however, there was another and dif­ferent opening through which the debris that partly fills the cave has been washed in. In addition to bones of small animals, this cave contains teeth and bones of the elephant. The sabre­tooth tiger has also been reported. With these bones there is associated a number of specimens of the land snail, Bulim1dus dealbatus. The presence of this fossil suggests that the cave deposits probably are not older that the deposits of the Medina flood plain which this snail, so far as present observations have shown, first appears in the stratigraphic succession. The presence of the snail together with the elephant remains sug­gests that the cave deposits are probably contemporaneous with the flood plain deposits of the Medina river.• RECENT The Recent deposits of this area are chiefly those in the flood plains of the streams. Near the foothills of the Edwards Plateau, the streams, although for the most part intermittent in flow, have great volume and velocity for a short time following heavy rains. For this reason the beds of the streams near the foothills contain a large amount of flint and limestone boulders and rock fragments, derived from the limestones of the Balcon~s fault zone and of the Edwards Plateau. In passing southward away from the foothills, the materials of the flood plains are found to contain relatively less of the heavy rocks and boulders and relatively more of the silts and clay loams derived from other formations through which the stream flows. In the southern part of the county the materials of the flood plain of the streams are chiefly silt, loam, and gravel. The gravel in the stream beds is relatively free from objection­able silt and for this reason is much used in road building especially in that part of the county just south of the Balcones escarpment where the largest bodies of clean gravel are found. Some of the higher flood plains are utilized in farming, since -•rii. O. P. Hay states that he has obtained sixteen species of fossils from this cave (Letter of Nov. 6, 1919). Geology and Mineral Resources of Bexar County only occasionally are they overflowed. On the Medina River the high recent flood plain has frequently been utilized in pecan growing. In mapping, the flood plains of the streams have been in­cluded with the late Pleistocene flood-plain. The flood plains of all of the streams are narrow and could not well have been suc­cessfully represented on a map of the scale used for this report. CAUCAREOUS CONCRETIONS OF THE PLEISTOCENE OF BEXAR COUNTY (Pl. 1, p. 72) In connection with the description of the Pleistocene flood plain deposits it has been noted that calcareous concretions are present and in places are very abundant. Concretions of this nature are particularly numerous in the deposits referred to the Leona formation where they make up, over considerable area, the greater part of the formation, especially in areas adjacent to the San Antonio River and Salado Creek. Similar concretions are found locally in deposits that, judged by their present ele­vation above the stream levels, are to be referred to the Uvalde formation. In the literature the writer has been able to find only two references to these concretions, both of which unfortunately are merely abstracts of more extended papers. The earliest of these is a brief reference in an informal communication on various kinds of concretions made before the Geological Society of Washington at the meeting of January 25, 1911, by C. W. Hayes. The abstract of this paper given in Science is very brief, that part of it referring to the concretions from Bexar County being as follows : Calcite concretions from San Antonio, Texas. These occur in great abundance in the "tepetate" or "caliche," a widespread chalky limestone formation, produced at or near the surface in semi-arid limestone regions by the ascent of water through capillary action and evaporation with deposition of the dissolved salts. Ordinarily the deposit has a platy structure, but in places, as at San Antonio, it is strongly concretionary.• A paper on these concretions was read by Alexander Deussen at the California meeting of the Geological Society of America, ~i. New Ser., Vol. XXXIII, p. 550, April 7, 1911. University of Texas BU:Zletin 1915. The abstract of this paper, published in Volume 26, No. 4 of the Bulletins of the Geological Society of America is 'I ery brief and does not include the author's conclusions. However, in reply to an inquiry by the writer, Deussen has stated that his investigations led him to the conclusion that these concretions were formed from thermal springs.• The suggestion that these concretions were formed from thermal springs appeals to the writer as both reasonable and probable. It is probably not accidental that these concretions lie down stream from the location of the pronounced breaks or faults from which springs now issue supplying the present streams of San Antonio and Salado. It is true that these faults cross other creeks, as for instance Leon Creek, but in .the case of Leon Creek the faults are so nearly sealed as to allow very little water to emerge at the surface, and on Leon Creek there is found no accumulation of these concretions such as are found near San Antonio and Salado Creeks. That the water of these springs during the Pleistocene period was thermal or at least somewhat warmer than at present is probable. If the deep waters emerging at that time were thermal, the continued cir­culation of water through the rocks, emerging at the springs during and since the Pleistocene would tend to reduce both the temperature and the amount of solids carried in solution by the water. It may be noted in this connection that the waters of the Comanchean formations at the present time are found to be warm and to carry a heavy load of solids in solution in wells drilled a few miles southeast, that is down the dip, from the existing springs. The area occupied by tnese concretions includes a narrow belt on either side of the San Antonio River for several miles south of San Antonio, and a much larger belt lying at the northeast side of the Salado Creek. This belt on Salado Creek has a width of two or three miles and extends for five or six miles south of the Seguin Road crossing. ---;utter of August 18, 1919. Geology and Mineral Resources of Bexar County STRUCTURAL GEOLOGY The formations in Bexar County, both those of the Cretaceous and Tertiary, dip toward the Gulf Coast. The rate of dip, however, is changed and the county is divided both structurally and physiographically into two very distinct provinces along the line already referred to, known as the Balcones Escarp­ment, which in this county faces south-southeast. The struc­tural conditions are very different in these two provinces. North of the Balcones Escarpment, the formations depart but little from the horizontal position, the rate of dip south of the Colorado River having been estimated by Hill and Vaughan to be not more than 10 feet per mile.• The structure in the coastal plains area of this county is much more complicated than is that north of the Balcones Escarpment, being affected both by faulting and by folding. At the inner or north margin of the Coastal Plains area are large faults, while farther to the south are other faults varying from small to large, accompanied by folds. The downthrow in most, although not in all, of the faults, and in the largest faults, is to the southeast or coastal side. The structures are in some, perhaps all, instances asym­metrical, the longer slope being on the southeast side. The com­bined effect of faulting and dipping, although varying from place to place, results on the whole in carrying the formations rapidly to a lower level in passing toward the coast. The lines of faulting and folding in the coastal plains area either approximately parallel the main or first large fault of the Balcones fault zone, or they diverge to the south, and plunge to the southwest. The southwest plunge of the formations, as well as the divergence to the south from the line of the main fault, are possibly incident to the change of direction of the fault zone in this and the adjoining county, to which reference has already been made. LOCATION OF PRINCIPAL FAULTS The first large fault of the fault zone is that which brings the Edwards formation against the Glenrose. Helotes Creek at the Bandera Road crossing flows in this fault; the downthrow side of the fault, the Edwards limestone, being exposed in the ~S. Geol. Surv., 18th Ann. Rpt. Part 2, P. 258, 1898. z 1100 ,... 9 3 4 5 6 7 8 llOO -60<> ''"~fw ­ '''' ~,, ~~ ,,"}~ ~ "' '''' ''' ' '' ,,',' fw 2/X) ''''' -1''',, 2. MIL ES .,~6 .;·''· [•''"'\'.' MILES 6MILES ~~~' ·~".':~\;)' '',, ,''' ' '' -:.' ~00 f~I~, 1...-·····­ Em d OO 4 00 fDi11~' ..~· t--:: ~1 800 ·1000 l~ """ mt{~; 11oct' 1400 -:i 00 10 ,,,, '·, '' ,,,, ~ z. '',,,'\. E-~ ,,' ~ ,' ? _ .. ~­ ', I l - ~ ~__:_-:.., Em ­ c ~ {b ~1 !:1 "" e ~ ~ ~ I ~ ...... {b "' -~­ "" Fig, 4. Graphic representation of well logs. Wells arranged In order from northwest to southeast, on and near the Fredericksburg and Pleasanton Roads. The approximate distance between wells is Indicated. N"o. 1, Government well on Leon S'prlngs Military Reservation; 2, Government well on Camp Bullis M111tary Reservation; 3, San Antonio City well, Brackenridge Park; 4, Government well, Fort S'am Houston Military Reservation, San Antonio; 5, well at Steves Gardens, ·S'an Antonio; 6, S'.an Antonio Olty Water S'upply well, near Conception Mission; 7, Hill and Roby well, about seven miles south of San Antonio; 8, Wolfe and Elder well, Alta Vista field, about eight miles south of San Antonio; 9, Mathey well of the Bexar Petroleum Comp8.J1y, n'ear Losoyo; 10 Park Oil and Gas Co. J. K. Lamb well south of Medina River. Per, Pre-Cretaceous; Ktp, Travis Peak; Kgr, Glenrose; Ke, Georgetown-Edwards; Kdr, Del Rio; Kb, Buda; Ket, Eagleford; Ka, Austin; Kt, Taylor; Kn, Navarro; Em, Midway; Ew, Wilcox; Pl, Pleistocene. ~ ~ 0 .,.., 0 ~ ! Fig. 5. Schematic representation of structure on an approximately north-south cross section following the Fredericksburg ~ and Pleasanton public roads. In this reduced sketch no attempt is made to indicate folding which to some extent at least ac­ ~· companies faulting. A, location of the first large fault of the Balcones fault zone, downthrow to the south; B, small fault seen ~ ~ ..... on the S. A. P. Ry. about 14 miles north of San Antonio, downthrow to the north; C-D, location of principal large faults within ~ the city of San Antonio. E, fault with downthrow to the north (or abrupt reverse dip) believed to exist north of the Alta Vista Oil ~ field; F, approximate location of a fault with downthrow to the north, or of abrupt reverse dip south of the Medina River. 0 ~ (') "' ~ 0 ....... b::I ~ ~ ~ ~ .,..., ~ -1 water. The Del Rio consists of clays chiefly while the Buda is a close-grained limestone, neither being sufficiently porous to be well adapted as water reservoirs. A few strong flowing wells are reported as terminating in the Buda formation. Probably, however, in these instances the drill enters fracture zones in the rock, the >Yater obtained being derived from the underlying water-bearing limestones. These formations, however, par­ticularly the Del Rio, form the overlying impervious stratum which confines the artesian waters within the Georgetown­Edwards limestones. University of Texas Bulletin WATER OF THE EAGLEFORD AND AUSTIN FORMATIONS As a water-bearing rock, the Austin formation is somewhat unreliable. A considerable number of wells have obtained good water in moderate quantities from this formation, but on the other hand, a large number of wells drilled into this formation have secured water containing too much hydrogen sulphide gas to be desirable. The formation contains con­siderable quantities of pyrite and doubtless the hydrogen sulphide in the water is incident to the oxidation of the pyrite. The water is obtained chiefly from the limestones of the lower part of the formation. The Eagleford formation, which lies below the Austin, is relatively thin in this county and consists of calcareous shales. It contains as a rule relatively little water. WATER OF THE TAYLOR AND NAVARRO FORMATION::; The Taylor and Navarro formations, which consist chiefly of compact marls, clays, and shales, nearly a thousand feet in thickness, are essentially non-water-bearing. Wells drilled through these formations in the Leon Creek gas field, the Alta Vista and the Somerset oil fields, report very little water until within the middle or lower part of the Austin formation. There are, therefore, very few water wells terminating in these forma­tions. WATER OF THE TERTIARY FORMATIONS The sand lenses which are often numerous in the Tertiary formations afford moderate supplies of good water. Wells terminating in these formations supply water in sufficient quantities for household purposes at Somerset, Elmendorf, and elsewhere in the southern part of the county. For the record of numerous wells in this county, see the section on well records. SPRINGS The permanent surface waters of this county are derived from springs, the largest springs of the county being those in Geology and Mineral Resources of Bexar County 105 San Antonio at the headwaters of the San Antonio River, and on the Salado River a few miles east of San Antonio, and in San Pedro Park. These springs are located near fault lines and without doubt are supplied from the underground artesian reservoir, the water escaping to the surface through breaks in the rock incident to faulting. The following observations have been recorded, which seemingly establish the connection between the artesian reservoir and the water from these springs: ''A few years ago a series of stakes was driven in the still waters of the head lake (of San Antonio River) and the height of the water marked thereon. The artesian wells were then all turned on and let run for twenty-four hours. The level of the water in the head lake or pond of the river had fallen 2 inches. The wells were then checked and in about one day the "'ater in the head lake \YaS at its former level. Then again the artesian wells were by survey connected in a system of levels. An excavation was made on the land of the observer below the \Yater line. It was possible by observing the height of the water in this hole to obtain the height of water in any artesian well in the city".* WAR::\I SULPHUR WATER IN THE COMANCHEAN LDIESTONES Xumerons \H'lls drilled in Bexar County have shown that from a few miles south of San Antonio the ·water obtained from the Georgetown-Edwards limestones is warm sulphur \Yater. The transition from non-sulphur to sulphur water in these formations, in passing to the south, is probably not as abrupt as some of the ·well records seem to indicate. The somewhat gradual transition from the non-sulphur to the sulphur 'rnter areaf: is indicated by the slightly sulphurous 'rnters of senral \vells near the dividing line between the two areas. Xo wn· satisfactory explanation has been offered to ac­ count for this change from non-sulphur to sulphur water in these formations. However, in passing to the south or south­ *The Water Powers of Texas, by Thomas U. Taylor. U. S. Geo!. Surv., Water Supply and Irrigation Paper No. 105, p. 25, 1904. University of Texas Bulletin east, the water-bearing formations drop rapidly to lower levels and hence are more deeply buried beneath the surface It is reasonable to assume also that there is less circulation of water in these formations where deeply buried than in the same formations lying near the surface, especially within the general region of the location of fissure springs which probably have permitted the escape of water and consequently circula­tion in the formations since as early at least as sometime in the Pleistocene period. The boundary line of the sulphur water area conforms in general with the lines of structure, and is ap­proximately coincident with one of the lines of heavy faulting. Increased depth and increased chemical activity together with reduced circulations may account for an increased temperature in these waters. SOURCE OF HYDROGEN SULPHIDE IN UNDERGROUND WATER The probable sources of the hydrogen sulphide in ground waters may be summarized as follows: The decay of organic matter containing sulphur; the reaction of organic matter upon sulphides or sulphates; the reaction of acids upon sulphides; the partial oxidation of sulphides. Hydrogen sulphide is formed during the decay of both animal and vegetable matter, and is obviously a possible source of hydrogen sulphide in underground waters. The hydrogen sulphide found in shallow waters in particular is doubtless very frequently from organic sources. Thorpe states that the decay of organic matter in contact with sulphates results in the formation of H2S.* The reaction in this case probably results from reducing properties of decaying organic matter, the sulphates being first reduced to sulphides according to the fol­lowing reaction: Na2S04 + 0 2 (carbon of organic matter) =2C02+Na2S. 'l'he sulphide is then acted upon by the car­bonic acid to form H2S as follows: Na2S+II2 003 = H 2S+Na2 C03• The reaction of organic matter upon the suphides is regarded by Van Hise as another important so11rr•' of H 2S in underground water.t The formation of hydrogen sulphide as a result of action of *Dictionary of Chemistry, Vol. III, p. 697, 1900. tA Treatise on Metamorphism, Mon. XLVII U. S. Geol. Surv., p, 1112, 1904. Geology and Jlineral Resources of' Bexar Co11nty 107 acids upon metallic sulphides is one of the most familiar of laboratory experiments. This suggests the possibility of the formation of this gas as the result of the action of acids upon metallic sulphides contained in the rocks. Sulphides, especially those of iron, are widely scattered in the earth's crust and occur in sufficient quantity to account for the formation of H2S gas in water. Hydrogen sulphide is a w·eak acid and its salts are decomposed by a stronger acid. Sulphuric and other mineral acids should certainly react upon sulphides liberating H~S. Carbonic acid when abundant reacts upon alkali sulphides to produce hydrogen sulphide. It is true that the alkali sulphides are normally not abundant in the crust of the earth. Stokes has shown, ho"·ewr, that the reaction of sodium carbonate within the earth upon pyrite or marcasite produces sodium sulphide. The reaction given by him is as follows: 8FeS2+ 15Xa2C03=4Fe"03 +14Xa2S-!--Ka2S20 3 +15C02.* It is a well known fact that the carbon dioxide which unites with water to form carbonic acid is abundant in the deep waters, especially in the limestone formations, the pressure ex­isting at considerable depth enabling the water to hold great quantities of carbonic acid. The series of reactions given by Stokes accounts for the presence of alkali sulphides in solution in the deep waters. It may be added that all sulphides are soluble to some extent in 'rnter, and in that condition may be acted upon b~-carbonic acid. t The partial Dxidation of sulphides is, according to Van Hise, a possible additional method of the formation of hydrogen sul­phide. the reaction being as follff\YS :t 3FeS2+4H20 + 40=Fe30,+4H2S +2S02 The oxidizing precesses are the most rapid near the surface, especiall~· abon the underground 'rater leYel, and H"S derived from this source probably supplies relatively shallow, rather than deep 1raters. Since iron sulphide (pyrite) is kno'rn to be present in the *From Van Hise, loc. cit., p. 1107. Tlnorganic Chemistry. International Library of Technology. Sec. 12, p. 11. tinorganic Chetnistry. International Library of Technology. Sec. 12, p. 1113. University of Texas Bulletin water-bearing formations it seems probable that the hydrogen sulphide of the deeper formations in Bexar County is very largely from this source. CEMENT The one cement plant in operation in this county at the present time is that of the San Antonio Portland Cement Com­pany, located on the International and Great Northern Railway two miles north of the north city limits of San Antonio, at the north side of the range of Austin Hills already referred to as originating at San Antonio and extending northeast (Fig. 2). The location appears to be near the contact of the Austin and Taylor formations. The materials from which the cement is made accordingly include the uppermost strata of the Austin formation together with more clayey material overlying this rock, which may represent the Taylor formation. The rock of the Austin formation is here of a light yellow color and of medium hardness. Upon partial disintegration, it breaks by €xfoliation and upon further exposure crumbles to small frag­ments. The rock as seen in the face of the quarry is much broken by jointing, including small faulting. The dividing line between this rock and the more clayey material above is distinct .and well marked. Overlying the clay and rock is a surface accumulation of gravel and pebble deposits. The gravel overburden is removed and the underlying clay and rock after being loosened by blast­ing is loaded into tram cars by steam shovel and in the case of the harder rocks, by hand. The thickness of the clay stratum overlying the rock probably increases as the quarry is worked back into the hill. In practice, however, it is found necessary to use only a limited amount of clay mixture with the rock of this focality. The product of the quarry is marketed under the name of the Alamo Portland Cement. An analysis of the limestone and clay utilized in this plant was made some years ago by the Bureau of Economic Geology under the direction of Dr. W. B. Phillips, and is recorded on Geology and Jlineral Resources of Berar Cv11nfy 109 page 65 of Bulletin 365 of the rninrsity of 'I'exas. The analyses are as follows: Limestone Shale (clay) per cent per cent Silic:i. . ... .. .. . ...... ...... 7.80 55 .30 Alumina ..... . ............ 3.45 13.56 Oxide of iron . . . . . . . . . . . . . . 1.35 4.50 Lime ....... . . . ...... ... .. 46 .64 9.48 :'.\Iagnesi:i. .. .. .... ... . . ... .. None None Carbonic acid ..... .... ... .. 36.65 7.45 Loss on ignition ... ... . .... 3.35 8.85 99 .24 99.14 Former!:·, the limestone of the ~.\ustin formation exposed in what is nmY Brarkenridge Park at the north rit:' limits of San Antonio was utilized in cement rnanufarture. Remnants of the old plant are still to be seen. and the sunken garden of Bracken­ridge Park marks the location of the pit from "·hich 1rns re­moYed material for cement manufacture and to some extent for other purposes, such as road material and ballast. The firm operating at this localit:·, the Alamo Portland Cement Company, was the predecessor of the present San Antonio Portland Cement Company. UXDEYELOPED PORTLA"D CE:\IE~T RESOCRCES In addition to the plant now operating in Bexar Count:·, it is probable that other localities are found 1Yithin the county capa­ble of deYelopment for Portland cement manufacture. In select­ing such localities, ho1Yewr, it is important to giYe careful attention both to transportation and to raw materials. The !oration should be easil:· within reach of rail transportation and should, of course, be faYorably located ii'ith regard to raw materials. Since in the manufacture of Portland cement there are re­quired both limestone and clay, it is essential that a location for a plant be selected "·here these ingredients are both readily available. Approximate!~-three times as much limestone is used as clay; or more, if the limestone contains clayey impurities as it often does. Favorable localities, therefore, are those in which clays and limestones may be obtained from the same pit, such as are to be found on the contact line between limestone and University of Texas Bulletin clay formations. One such contact is that between the Austin and Taylor formations on which, as already stated, the plant of the San Antonio Portland Cement Company is located. By reference to the map showing surface outcroppings of the for­mations, the approximate line of separation between these foCTrlations may be located in the county, thus aiding in the search for such favorable localities. Another geologic horizon worthy of attention in this con­nection is that of the Del Rio clay together with the underlying Georgetown-Edwards limestones and the overlying Buda lime­stone. The Del Rio clay in this county has an average thick­ness of from 65 to 70 feet. The Buda limestone, which lies above this clay, is a very close-grained, quite pure limestone, having a thickness when fully developed of about 60 or 65 feet. The Georgetown-Edwards series of limestone below the Del Rio clay has a thickness of several hundred feet. The Del Rio clay, as noted in the description of that forma­tion, contains in places considerable pyrite and gypsum. In considering this clay for cement manufacture it will be neces­sary to make sure that these ingredients are not present at the locality selected. Nodules of calcium carbonate such as are sometimes present in this clay are, according to Eckel•, also to be avoided. The Buda limestone is a dense and usually very pure limestone rock, having a thickness of from 60 to 65 feet. Following is an analysis of the ·limestone of this formation as developed in the Chisos Mountains of Trans-Pecos Texas. The formation as developed in Bexar County probably differs to some extent from that used in this analysis, but the test is nevertheless illustrative of the chemical composition of the rock of this formation. Analysis of Buda limestone from the Chisos Mountains. From the Buda Horizon, one mile east of Boquillas.t Per cent Silica ..... ..... ... . . .. ..... . .. .... . .. 2.35 Alumina . . . . . . . . . . . . . . . . . . . . ... . . . . . . . .21 *Cement Materials and Industry of the United States. U. S. Geol. Surv. Bull. 243, p. 38, 1905. t A Sketch of the Geology of the Chisos Country, Brewster County, Texas. By J. A. Udden, Bull. 93, University of Texas, p. 28, 1907. Gt-ology and Jlineral Resources of Bexar County 111 Per cent Ferric oxide . . . . . . . . . . . . . . . . . . . . . . . . . .24 Lime . ... . . .... .... .. . . ..... ..... ... . 53.90 :'.\Iagnesia . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15 Carbonic acid . .. .. . ........ . ......... 42.23 Water (hygroscopic) . . . . . . . . . . . . . . . . . . .18 Water (combined) . . . . . . . . . . . . . . . . . . . .33 Sulphur .. . ..... . ............. . . . ... . Trace 99.59 The Georgetown-Edwards series of limestones lying beneath the Del Rio clays has a combined thickness of several hundred feet. The Edwards limestone contains at some horizons large masses and layers of flint such as would render it undesirable for cement making. The upper part of this limestone series, however, probably chiefly in that part of the section represent­ing the equivalent of the Georgetown formation, contains relatively little flint. Hence there is an opportunity of finding limestones suitable for cement-making underlying, as well as oYerlying, the Del Rio clays. By referring to the map it will be seen that the San Antonio and Aransas Pass Railway crosses the formation referred to in the northern part of the county. Another formation that should receive consideration in a search for cement materials is the Eagleford. This forma­tion, \Yhich consists of calcareous shales with interbedded thin limestones, lies between the Buda and Austin formations. In Bexar County t~1c Ea~dcford formation as already stated is but little deYelopcd, haYing a thickness of about 30 or 35 feet only. Its distribution is such that surface exposures are numerous in which this formation is found lying upon the Buda Limestone, or underlying the hard limestones at the base of the Austin formation. ?\o chemical analyses of the Eagle­ford shales of Bexar County are at hand, and so far as the writer is aware, no attempts have been made to utilize this formation in this county in cement manufacture. In Dallas County, the shales of this formation are combined with the University of Texas Bulletin limestones of the overlying Austin formation m the manu­facture of cement.* CLAY The clays of Bexar County are found chiefly in the Del Rio, Taylor, Navarro, Midway and Wilcox formations. The days of the Del Rio formation are referred to under the discussion of cement materials. The clays of the Midway and Wilcox formations are utilized in the manufacture of building bricks. The clays of the other formations are undeveloped in this county. BUILDING BRICK Three plants in this county are producing building brick. These are: the Bern Brick Company, San Antonio; the Star Clay Products Company, Elmendorf; the San Antonio Sewer Pipe Works, Saspamco. In the plant of the Bern Brick Company the clay used is that of the Midway formation. According to unpublished notes of C. L. Baker, the clay of this pit is a dark blue-gray, easily slaking clay, carrying much fibrous and platy selenite, and weathering light yellowish and drab, containing large brown cone-in-cone concretions and small nodules of limonite. The fossils recognized were T1trritella mortoni, Venericardia, Voluti'lifhes, and Dentaliiim. The clay of this pit is very sim­ilar to that exposed in the cut of the Missouri, Kansas and Texas Railway nearby. The bricks made from this clay burn to a light red color. Up-draft kilns are used, with mesquite wood as fuel. The bricks burn to a light red. The clay used by the Star C1ay Products Company is from the Wilcox formation. The manufacturing plant is at Elmen­ dorf, but the clay pits are on the south side of the San Antonio River, about four miles from Elmendorf, the clay being trans­ ported from the pit to the plant by aerial tram. The following description of these clays is from notes made by Mr. Baker. *The Geology of Dallas County. By Ellis W. Shuler. Univ. of Tex. Bull. No. 1818, p. 35, 1918. Geology and Mineral Resources of Bexar County 113 In the clay pit the dip (perhaps not greatest) is 8° in the direction south 2 0 ° west. The ·wilcox here consists of coarsely-laminated clayey sands. The sand is medium-grained and contains flakes of muscovite, some layers being more clayey, while others are lami­ nated with thin seams of limonite. The clay is taken just as it occurs without sorting. The clay contains many leaf impressions. Layers of bluish white clay six to eight inches thick occur in the upper half of a fifteen foot section. These clay layers, if thicker, would probably make pottery clay. The overburden at the pit consists of alluvial material amounting to from four to fifteen feet . This covering is often cemented with iron oxide indicating a near approach to the Mt. Selman formation. After removing the overburden the clay is plowed and dumped into tramway cars and hauled a couple of hundred feet by mule, and then attached to aerial tramway. Mexican labor is used. This company formerly made jars, crocks, jugs, and flower pots, both glazed and unglazed, out of picked blue clay. At the present time this firm is making hollow tile and some brick. The tile and brick are wet-molded, then dried in kilns. Crude oil is used for firing the kilns, lignite being used for the boilers. One of the pits of the San Antonio Sewer Pipe Works is in Bexar County near the south boundary, while the manufactur­ing plant and other pits are just across the line in Wilson County. 'fhe clay used is from near the top of the Wilcox formation. The following description of this plant is from the notes taken by l\fr. Baker: The overburden at the pit in Bexar County is a cross-bedded sand from 10 to 12 feet thick. The upper six to eight inches are light gray, below which is found four feet of light brick red sands, while the remainder beneath is a light brownish red. The sands are often mottled with red, the mottling being sometimes bordered with limonite or other cement. This overburden is removed by steam shovel. The dip in this pit as indicated at the contact between these sands and the underlying clay is one degree to the south. The total thickness of the clay worked at this pit is about 18 feet. The clay is blue-drab in color and slakes on long exposure to the weather. It weathers in bedding planes and joint cracks with a rusty to brick red coating of limonite. It contains small nodules of limonite and stains of yellow alum. It contains also many well preserved fossil plant impressions, especially leaves of dicotyledon· ous plants. At the manufacturing plant the clay from this pit is mixed with sandy clay from another pit. This company, which has been in 8-Bex. University of Texas Bulletin operation for twenty-two years, originally made stoneware, but is now making sewer pipe, drain tile, and wall c.opings. The beehive type of kiln is used. The clay burns dark brown. FULLER'S EARTH The fuller's earth deposits of Bexar County are being ex­ploited at the present time by but one firm, the Medina Fullers Earth Company. The deposit that is being mined is located near the headwaters of a small stream north of the Castroville Road and west of the Cagnon cross road about 16 miles from San Antonio. The plant at which the earth is dried, ground, and prepared for market is located in San Antonio, the crude earth being hauled from the pit by trucks. In the pit at the present time there is seen an exposure of as much as 35 feet of workable fuller's earth. The overburden is moderate con­sisting of a few feet of soil and gravel. The fuller's earth is of a light gray or drab color, becoming lighter colored upon drying. Upon fresh fracture, the clay breaks in a very characteristic manner which suggests at once the resemblance to the divisions of shells of ammonoids. The clay is seemingly entirely free from sand, and contains little if any calcareous material. When placed in water, or upon long exposure, the clay slakes into very finely-divided material. The soils derived from it are sticky, and with the inclusion of organic matter become dark in color. The fuller's earth beds themselves contain no fossils, so far as observed. Their relation to the overlying fossil-bearing beds indicates, however, that they are either of the Navarro or Taylor formations of the Upper Cretaceous. From the record of the well drilled at the pit the place of the fuller's earth bed appears to be about 600 feet above the base of the Upper Cretaceous. Of this interval, the Eagleford and Austin forma­tions occupy between 335 and 400 feet. While the records are less exact than could be desired, the fuller's earth bed of this pit is placed provisionally with the Taylor formation probably near its top. In the cut at the entrance to the plant a short distance northeast of the pit and also on the hills near the pit, are found exposures of the yellow clay containing an Geology and Mineral Resonrces ol Bexar County 115 abundance of the oyster Exogyra costata. These exposm·es lying at a slightly higher level probably indicate the Navarro formation. The fuller's earth produced by this company is crushed into pieces of moderate size, not exceeding two or three inches in diameter and is then passed through a rotating drying cylinder to remove the excess of moisture. The clay is then ground and sacked for market. It is said to be chiefly used in clarifying vegetable oils including cottonseed oil, for which purpose the present practice is to grind the earth to pass a 200-mesh sieve. It is used also in clarifying lard. Aside from the finely ground earth, a part of the product is ground to a mesh of 16-32-60, the earth of this grade being used for mineral oils. BF:XTOXITE In addition to the fuller's earth there is found in this county also in the Upper Cretaceous formations the material known as bentonite. The bentonite deposits of this county have been described in a circular previously issued by the Bureau of Economic Geology, which for convenience of reference is here reprinted. The circular was based on the work of l\Ir. C. L. Baker. In. the course of work in Bexar County, the Bureau of Economic Geology and Technology of the University of Texas has discovered a bed of the peculiar clay called bentonite, heretofore known only from Wyoming. Bentonite bas the property of absorbing large quantities of various liquid substances. ·when freshly exposed, it is generally light yellowish-green or creamy white in color and bas the appearance of wax. It often appears as a joint clay, breaking with a conchoidal fracture into roughly rectangular blocks. On surfaces exposed to the weather the outcrop looks much like that of ordinary clay, so it is necessary to dig in and expose the fresh material in order to be certain that bentonite really occurs. Ben­tonite has a soft, soapy feel, has very little or no grit, and is brittle. ?IIixed with the proper amount of water, it becomes very plastic; it differs from all ordinary clays or kaolins in being easily fusible at moderate heat. When placed in water it rapidly swells up and slacks, like quicklime. It completely absorbs over three times its weight or seven times its Yolume of water, and twice as much gly­cerin as diatomaceous earth will absorb. University of Texas Bulletin Bentonite has been put to various uses. It is used for the man­ufacture of hoof-packing, a dressing for the inflamed hoofs of horses; and also in the manufacture of the medical dressing, anti­phlogistine. Its chief use is to give body and weight to paper. It is also used as soap filler, in the manufacture of high grades of soap; to dilute powerful drugs in powdeTed form; and as an adulterant in candy. It is a good retarder for use with the hard cement plasters and would probably make a better absorbent of glycerin in the manufacture of dynamite than the diatomaceous earth now used for that purpose. Owing to its peculiar properties, it is likely to find more extensive and varied use in the future. Bentonite has so far been found in commercial quantities in two widely distant localities in Bexar County. Probably further work will show up a number of other localities or perhaps a continuous bed outcropping across the country in an east-west direction. Cine of the known localities is in a long white bluff on the east side of Lucas Creek about 14 mile northeast of the oil derrick on the B. F. Masterson ranch, north of the Castroville road in the western part of the county. The other locality is on Salitl'illo Creek on the F. Siebold land, in the eastern part of the county. The bentonite has been found in a low north bank, a short distance downstream from the old road crossing the Salitrillo Creek. CONCRETE The concrete materials of Bexar County are obtained from the hard limestones, flints, cherts, and from the pebble and boulder deposits of the stream beds and valleys. The lime­stones best adapted for crushing for concrete are of the follow­ing formations : the Georgetown-Edwards limestone series; the Buda limestone; the basal strata of the Austin Formation; and the heavy limestone concretions of the Midway and Wilcox formations. In addition there are certain hard limestone ledges in the Glenrose and in the Eagleford and probably in some other formations that will serve this purpose. By reference to the map the general distribution of the surface outcroppings of these formations may be located. The fl.int and cherts that may be used for concrete are chiefly those of the Edwards formation. The gravel an.d boulder deposits of the stream lieds include material derived from the other formations, especially from the heavy Coman­chean limestones. The stream deposits contain as a rule a mixed accumulation of fl.int and limestone pebbles and Geology and Jlineral Resources al B exa r County 117 boulders. The deposits of this kind are best developed in the Recent and Pleistocene stream beds for several miles south of the Balcones Escarpment. In all the central and northern parts of the county concrete materials may be obtained locaPy or at least by transportation for no more than a few miles. GREEXS.\XD The Navarro formation as developed in Bexar County is characterized by beds of greensand, the distinguishing feature of "·hich is the presence of the green-colored mineral, glauconite; a mineral containing a small amount of potassium. Numerous exposures of the greensand strata of this formation are found in the county. Of these perhaps the best kno"·n is an exposure at the south bank of Leon Creek between the CastroYille and Pearsall road crossings. An analysis of this greeilsand has been giYen by Dr. \Ym. B. Phillips in Bulletin 365 of the rniYersity of Texas, Page 69, 191-1. The account of thi,5 phosphatic greensand deposit giwn by Dr. Phillips is as follows: On Leon Creek, about 7 miles \\·est of San Antonio, on the Castro­Yille Road, there is a heavy deposit of phosphatic greensand of the following comJJOsition :· Per cent Silica ...... .............. ..... ...... 35.lS Alumina . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.30 Lime . . . ......... ... . .... . ... . .... .. 16.00 Oxide of iron . . . .... ............. .... . 17.25 '.\Iagnesia .... . . .. ................. . . . Trac<.> Soda ... ........ . .. . . . . ............. . 1.39 Potash ... ....... .. . . . .. .. . . . ... ..... 1.69 Carbonic acid . . . . . . . . . . . . . . . . . . . . . . . . 8.00 Loss on ignition .... . ................. 10.10 Phosphoric acid . . . . . . . . . . . . . . . . . . . . . . 3. 3 0 98.21 University of Texas Bulletin This deposit contains rounded phosphatic pebbles, from 1/8-inch to %-inch in diameter, of the following composition: Per cent Silica . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . 7 .5 O Alumina . . . . . . .. . . . ... ... ............31.03 Oxide of iron ................ ... ..... 4.58 Lime . ......... . ..... . . . ... . .........18.08 Carbonic acid ....... . ..... . .......... 4.60 Phosphoric acid ...... . ...............18.19 Loss on ignition ...... . ... .. ..........12.60 98.34 The larger pebbles are not abundant. For the most part, the pebbles are very small, less than 1-20 inch in diameter. An examination of 10 feet of this phosphatic green sand foot by foot gave the following results, from above downward : Phosphoric acid Per cent First foot ........... . . . ........... . .. 3.09 Second foot .. ......... ..... ........... 2.38 Third foot .. . . . . · ..... . .. . . ; ........ . .. 3.22 Fou:th foot ........................... 3.07 Fifth foot ..... ............. ........ .. 4.00 Sixth foot ...... ........ ... . . .........'2. 7 3 Seventh foot ...... . ............. . ......4.32 Eighth foot . . . . ..... . . . ...............2.60 Ninth foot .......... . .................3.70 Tenth foot . ... . .... . ... . . .. ... . ...... 3.97 Average . . .... . . ........ . . . ...3.30 The total thickness of the deposit is about 20 feet, and it sets in at from 4 to 6 feet below the surface. Taking the deposit as a whole, it carries enough lime, potasl and phosphoric acid to make it a good fertilizing agent. The rock is soft and easpy pulverized. It could be finely ground and used with distinct advantage on many farm lands in south Texas, especially those in the vicinity of San Antonio. With the exception of some "stray" phosphate· in Fayette County, the exact locality of which is somewhat uncertain, the phosphatic pebbles from Leon Creek carr;Y. considerably more phosphoric acid than any other known deposit in the State. LIGNITE Lignite is found in commercial quantities in Bexar County in the Wilcox formation of the Tertiary system. The areal Geology and JHneral Resources of Be.rar County 119 distribution of the surface outcropping of this formation is indicated in a general way on the accompanying map. In the well logs, lignite is frequently reported in this formation*. These strata lie at varying depths below the surface and are of varying thickness from one to several feet. The individual lignite beds are doubtless of relatively local development, but the frequency with which they are reported indicates the possibility of beds of commercial value at places in the part of the county occupied by the Wilcox formation. At the present time, a lignite mine is being opened up about 11/z miles west of Somerset. The company operating here is the Brackenridge Coal Company. The test pits indicate a lignite bed having a thickness of from 5 to 9 feet, lying about 44 feet below the surface, and including a sufficient areal extent to justify development. A branch line is now being built to the mine from the Artesian Belt Railway. LDIESTONE The limestone resources of this county are extensive. The Gomanchean system in particular contains a great succession of thick limestones, particularly those of the Glenrose, Ed­wards, Georgetown and Buda formations. In the Upper Cretaceous the Austin formation is the chief limestone member. The distribution of these formations is indicated on the geo­logic map. The limestone formations are crossed by several of the railroads, particularly by the San Antonio and Aransas Pass Railway north of San Antonio. The limestones suitable for cement and lime manufactnrf:, and for building stone and road materials are separately dis­cussed. Another possible use for the limestones is to grind and apply to acid soils. As is well known many of the soils of *It is necessary to distinguish in well logs between the term "lig­nite" as used by drillers operating in the central part of the county, and the same term as used by drillers in the southern part of the county. The latter refer to the true lignite of the Wilcox forma­tion, while the former refer to the dark carbonaceous shales of the Eagleford formation. University of Texas Bulletin the Gulf Coastal Plains are acid in reaction and are benefitted for some crops by the application of ground limestone. For this purpose a pure limestone is desirable, thus reducing the amount of inert matter that it is necessary to transport. Analyses of the limestones of the Austin and Buda formations have already been given. The following test of a samp'e of the limestone of the Edwards formation has previously been published in University of Texas Bulletin 365, p. 66, 1914 : Analysis of limestone from San Antonio Lime Company. Per cent Silica . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . o.70 Alumina . . . .. . ........ . . . .. .. ........ 0.28 Oxide of iron . ........................ 0.72 Lime ........ .. .... .. ..... .. ... ... ... 55.05 Carbonic acid .... . .. : ..... ..... ..... . 41.9 0 Loss on ignition .. .... . ... .. .... . ..... 2.10 100.00 Physical qualities: Crushed at pounds per square inch ..... . ..... . .. 6,666 Weight of cubic foot .... ........... ..........167.60 Per cent of cells by volume . . .... .. ... ... ... . ·.. 0.20 Volume of cells in a hundred parts by weight . . .. 0.07 Pounds of water absorbed per cu. ft.. . . . . . . . . . . . . 0.11 LIME The limestones suitable for the manufacture of lime in Bexar county are extensive. The Edwards formation is a very pure calcium carbonate and several. quarries have been opened in this formation for the manufacture of lime. Owing to un­favorable labor conditions no one of these quarries was in actual operation during 1918, although. it is expected that this industry will be resumed as soon as conditions will permit. The San Antonio Lime Company located on the San Antonio ::tnd Aransas Pass Railway 14 miles :from San Antonio us~ rock from this formation. The analysis of the limestone rock used by this company has already been given. With large quantities of limestone rock available for lime manufacture the success of a plant of this kind will be de­ Geology and Jiineral Resources of Bexar County 121 termined by the location with respect to markets, convenience and cost of transportation. RDLDIXG STOXE The limestone.<: of the Comanchean system offer very at­tractin stone for building, and are of service especially where c>onditions are such that they can be used without being transported and great distance. The Glenrose, Edwards, Georgetown and Buda formations are all capable of furnishing desirable building-stone. In the Upper Cretaceous the in­durated ledges of the Eagleford formation have been used locally for building. These hard layers have the advantage of uniform thickness The basal members of the Austin formation likewise include ledges of hard limestone available locall~-for building purposes. PETROLEC\I .-\XD XATL"RAL GAS Petroleum in Bexar County was probably first produced in commercial quantities from the Dulnig wells about eight miles east of San Antonio. Subsequently oil and gas have been diseoYerecl at other localities, and at the present time there are perhaps bet\Yecn 60 and 10 producing wells in the county. The oil has been obtained chiefly in the southern part of the county, south and south\\·est of San Antonio. .Although son1e\Yhat scattered, the producing '"ells, all of which are small in production. rirny be grouped as the 'vells are now kno\\·n into four or fiye more or less 'Yell defined fields or areas. The location of these areas is indicated on the key map to the resonrees of Bexar Count~-(Fig. 6). They are as follows: Alta Vista, :.\Iission. South :.\fedina, Gas Ridge, Somerset, and some oil \Yells southeast and sonth,Ycst of the Somerset field. The Alta Vista field lies about eight miles due south of San Antonio on the '"est side of the Pleasanton Road. The ~fission field lies about three miles 'Yest of the Alta Vista field, or about tweh·e miles slightly '"est of south of San Antonio. The Somer­ set field is near the Bexar-Atascosa county line J':: 1:1iles s·111th­ west of San Antonio. A gas and oil field lies between Leon University of Texas Bulletin and Media Creeks from eight to twelve miles r>outh ~vest oi San Antoni). To this field no name seems to have beert applied although it is referred to locally as the "Gas Ridge". South of the Medina River, three or four miles south of the Mjgsion field, several wells have been brought in recently, located on the Kimbley-Brown lease chiefly on the Swearingen property. A few additional wells are found in the county not included within any one of the areas mentioned. At the present time (1918) five wells are producing in the Alta Vista field, of which one flows and four are pumped. In and near the old Mission :field there are about seven wells producing. In.and near the old Somerset field within Bexar County, about :fifty small wells are now producing. All of the wells at present producing in these three :fields are small, mak­ing from two or three to :five or six barrels per day. In the Atascosa County extension of the Somerset :field, better wells are obtained some of which are reported to make :fifteen barrels or more per day. All of the wells thus far obtained in this county obtain oil from the Upper Cretaceous formations; in the Alta Vista and Mission :fields, from the Austin formation; and in the other fields chiefly from the Taylor and Navarro formations. The oil from the Austin formation is a heavy oil, reported to be about 14 or 15 degrees Baume, while that of the Taylor and Navarro formations is much lighter, averaging about 36 degrees Baume. Some of the oil from the Somerset wells may come. from the Midway formation. THE ALTA VISTA FIELD The :first showing of oil in the Alta Vista :field is said to have been in a well drilled for water. This led subsequently to other wells being drilled, and in September, 1915, the Mars Discovery well was brought in, the. initial production of which was reported at the time to be as much as 125 barrels per day. The impetus given to drilling by this and by subsequent suc­cessful wells led to very active development in this field for a short time. Subsequently the wells rapidly dropped off in production. Geology and Mineral Resources of' Bexar County 1:2~ THE MISSION FIELD The Mission oil field may be regarded as essentially the southwest,Yard extension of the Alta Vista field. The first well indicating oil drilled in what subsequently became known as the Mission oil field is said to have been drilled for water in June, 1901. This well showed oil at the depth of 275 feet. Following the discovery of this showing of oil, drilling was undertaken in this field by Nash and Fitzgerald who finally completed, in 1907, a 2900 foot well on the Linn farm. This deep well, a record of which is given under the section on well records, yielded a flow of sulphur water and was non-·pro­ductive of oil. In this field after passing through showings of light oil, heavy oil similar to that of the Alta Vista field is obtained at the depth of about 1000 feet. Sulphur water is encountered below the heavy oil as in the Alta Vista field. GAS RIDGE OIL AND GAS FIELD The Gas Ridge oil and gas field lies west of L•eon Creek and north of the Pearsall (Frio) road, and is located chiefly on what is known as the Hamilton-Swain and Cohen lands. Two wells were drilled in this field some years previous to 1916. Additional wells yielding gas and some oil were drilled during 1916 and at the time of the preparation of this report several additional wells were being drilled. This field was visited in 1916 by l\Ir. E. L. Porch, Jr., and the following extract is from the report made to the Bureau of Economic Geology by him at that time on the new \Yells then being drilled or recently com­pleted. These wells are all within a few hundred feet of two gas wells which were drilled here several years ago. The gas from one of these wells is used as fuel for the present work, the other well being connected up so that it can l.Je used if needed. There is a third well, about a half mile south of these two gas wells, which is said to have also been a gas well. .... Sarber well N'o. 1, in which oil was first struck, is located on the Hamilton-Swain tract, while Sarber No. 2 is located on the Abe Cohen tract. and is about 500 feet east of No. 1. Well No. 1 was University of Texas Bulletin drilled witb a standard rig, and is 492 feet deep. No. 2 was driJl.ed with a rotary rig, to a depth of 10 3 5 feet. At the time of my first visit on Friday, a packer was being placed in No. 1, and I could hear the gas bubbling in it. No. 2 was down about 1000 feet and was showing some oil and gas. I took a sample of the oil said to have come from No. 1, and samples of all of tee cuttings from known depths. There was a barrel of the oil near the derrick, and it had been standing some eighteen hou>s, but notwithstanding this fact, it smelled something like gasoline, and had a specific gravity of 29.1° Baume. The oil sand in No. 1 is said to be 2 2 feet thick. .On the afternoon of the next day (Saturday) oil was struck in No. 2 at a depth of 1035 feet, it being estimated that the drill pene­trated the "oil ,sand" less than a foot. On Sunday afternoon I made my second trip, but could not obtain a sample of the "oil sand," and all the oil I could secure was some skimmings from the slush pit. This oil ·has a specific gravity of 12.8° Baume, and ap­pears very similar to the oil obtained in the Alta Vista field, which i!l about 8 mil€s southeas~ of this field. These gas wells were said to have had an initial pressure of 350 lbs. per square inch, and they still have sufficient pressure (judging from observafions of the one I saw tried) to shoot a fiame out about forty feet from the mouth of a four inch pipe, with a roar that could probably have been heard over a .mile away.... The logs of the wells in this field indicate a succession of clay shale and gumbo. Chalky rock is noted in some of the deeper wells. There is little or no water in the higher forma­tions although water is doubtless to be expected in wells drilled somewhat deeper. The wells start, aside from the surface materials, in the Navarro formation. The shallow oil and gas with little doubt comes from the Taylor formation. The deeper oil, which is much heavier than the shallow oil, may come from the Austin formation. The gas is probably from the Taylor formation at the depth of about 800 feet. THE SOMERSET OIL FIELD As in the case of the Alta Vista and Mission fields, the Somerset field was discovered as the result of drilling for water. About 1913, Mr. C. Kurz while drilling for artesian water on his property two miles east of Somerset encountered oil which led to other wells being drilled by himself and others. Geology and Mineral Resources of Bexar County 125 The field in Bexar County now has about 50 small wells. In this field the oil immediately east of Somerset is reported as being obtained from hard shale at from 850 to 900 feet. South and south>vest of Somerset, however, the wells are deeper, reaching in this county a maximum of about 1250 feet. In the extension of the field into Atascosa County, somewhat deeper wells are required to reach the producing horizon. On the Kurz property boulders are reported as being en­countered occasionally to the depth of about 300 feet. Below this level is chiefly shale and gumbo. On the Witherspoon lease adjoining the Kurz property similar conditions are en­countered. The generalized log of the wells on this property is given by Mr. Kurz as follows: Alternating beds of sand and rock from the surface to the depth of 270 feet. Water in the formation at intervals to about 300 feet. Below about 270 or 300 feet is alternating shale and gumbo strata with little or no water. The wells on the Harrison property, Slimp and Davidson lease, south of Somerset, reach the producing sand at about 800 feet. The wells of the Crosby lease, on the other hand, near the county line, reach a producing horizon at the depth of about 1250 feet. THE SOUTH MEDINA OIL FIELD Several oil wells were brought in south of the Medina River during 1918 by Kimbley and Brown. These wells reach the producing horizon here at the depth of from 1250 to 1350 feet. The materials passed through are indicated by the logs of the wells kindly supplied by Mr. Brown, and published in the chapter on well records. The wells start in the Tertiary formations and probably terminate in either the Navarro or Taylor formation. In the Park Oil and Gas Co. test well, Apple­white No. 1, located less than one mile southeast of Kimbley and Brown, Swearingen No. 4, the Austin formation appears to have been reached at 1896 feet from the surface. RELATION OF THE BEXAR COUNTY OIL FIELDS TO STRUCTURE In the Alta Vista field the producing horizon lies more than 100 feet nearer the surface at the north side 0f the field than University of Texas Bulletin at the south side. A part and perhaps the greater part of this difference in elevation is accounted for by the small fault or abrupt monoclinal fold which passes through this field to which reference has already been made. The following data on the depth to the producing horizon in this field were secured chiefly from Messrs. Ross, Mull and Raborn, operators and drillers in this field. Wells of Alta Vista field arranged approximately in order from north to south. Depth to Actual level Name of well Elev. Prod. Prod. Horizon Horizon Ingram well .. . . . . .... . . 615 1020 405 Fuchs No. 2 ...... . . . . . . 615 1020 405 Aiken . . ...... . ..... . .. 605 1020 415 Mars Discovery ... . . . ... 600 1070 450 National Oil Co... . .. . . . . 585 1120 585 Busby Well .. . ...... . .. 555 1150 595 The most striking feature of these records is the apparent change in level of more than a hundred feet between the last two wells and those which precede. This change in the level of the producing horizon appears to be essentially in the line of the fault already referred to. In the Somerset field the data on structure are unfortunately -very limited. In that part of the producing area lying from % to 1% miles southeast of Somerset, the dip in the strata is pretty definitely shown to be to the southeast. On the Kurz property near the Artesian Belt Railway about 1% miles from Somerset, the dip was found from well records to amount to 40 feet in about one-third of a mile. In addition to a -southeast dip the structures in the vicinity of Somerset plunge to the southwest as is indicated by the increased depth of well in passing from Bexar to Atascosa County. On the Swearingen property south of the Medina River the dip in the producing horizon in a direction slightly east of south, as shown by the wells of the Kimbley-Brown lease, is as much as 115 feet in a little more than a mile in a direction slightly east of south. It is thus seen that the producing wells in the fields on which Geology and Jlineral Resonrces ol Bexar County 127 definite data are aYailable are located on the southeast slope of the structures. On other data already presented it is shown that these structures are asymmetrical, having a long south­east slope and a more abrupt northwest slope or limb; some of the structures possibly being at the northwest side by abrupt dips or by dips and faults. In extending explorations it ap­pears reasonable, therefore, to anticipate the possibility of similar structures with, in general, a northeast-southwest trend farther to the southeast from those already known. QUALITY OF THE BEXAR COUNTY OIL As has already been stated the oil obtained from the Austin formation is much heaYier than that from the overlying Taylor or NaYarro formations. The following gravity tests of the Bexar County oils have been made at various times in the testing laboratory of the Bureau of Economic Geology. The first three oils are probably from the Taylor or Navarro formations: the others are probably from the Austin formation. The gravit~-'ms taken at 60° F. No. 1. Crude petroleum from near Somerset, 18 miles south of San Antonio; gravity, 35.8 o B. );o. 2. From a well at Somerset, Bexar County; gravity, 30.7 ° B. Ko. 3. Said to have come from Sarber well No. 1, Hamilton Swain Tract, about 9 % miles southwest of San Antonio, at a depth of 492 feet: graYity 29.l o B. No. 4. Collected from scum of pit on H. Cohen Tract, Sarber No. 2 well, about 500 feet east from Sarber No. 1, at a depth of 1035 feet; graYity, 12.1 c B. Xo. 5. From Xational Oil Company N"o. 1, 1115 feet below sur­ fac: . in Alta Yista field, Bexar County ; graYity, 14 ° B. Xo. 6. From :\larr's Xo 1 well, Bexar County; gravity, 14 ° B. Ko. 'i . Crude oil from Kelso well No. 1, 8 miles south of San Antonio: graYitY, 14 c B. GENERAL CONSIDERATIONS The oil fields of Bexar County are located on structures which lie iYithin and are a part of the disturbed area of the Balcones fault-zone, the structure approximately paralleling University of Texas Bulletin the Balcones EBcarpment. The location of this county uear the turn of this fault zone from the northeast-southwest to an east-west direction accounts possibly for the very heavy faulting as well as for the southwest plunge of the structures. The structurally, high areas appear to be limited at either side in part by faults and in part by abrupt dips, the longest slopes being to the southeast. It is probable that the producing wells are located chiefly on the southeast slope of the structures. This is true at least for the Alta Vista, South Medina, and Som­ersat fields, the data on the Mission and Gas Ridge fields being at present less definite. Production in this county is from the Upper Cretaceous, the Lower Cretaceous not having been found to be producing. Wells drilled to test formations below the Cretaceous, if located in the central or southern part of the county, must expect to drill through 3500 feet or more of sediments before reaching formations older than the Cretaceous. Near the Balcones Escarpment the formations next beneath the Cretaceous have been found to be schists. Whether or not the Pennsylvanian or other formations come into the section farther to the south, between the Cretaceous and the schists, has not been determined. If wells are drilled in search of production below the Cretaceous, the more promising locations are on structures as far removed, the required drilling depth being considered, as practicable from the Balcones Escarpment. In the further development in the Upper Cretaceous and Terti­ary :formations it is suggested that structures already known may be followed in their southwest trend, and that other similar structures may be looked for to the south or south­east of those already known. ROAD MATERIALS The road materials in Bexar County include gravel, limestone rock and sandy clays. Of these materials the gravels are the most generally utilized, and are found in the stream beds and in the flood plain deposits of the Leona and Uvalde forma­tions. The distribution of the limestones and clays has already been indicated. Geology and Mineral Resources of Be.car County 129 WELL RECORDS In this section will be found records of the wells that have been utilized in making the contour map showing structure and in describing the water supply conditions in the county. Since in the structural map the key horizon used is the Del Rio formation, the actual level of the top of this formation is given for all wells as nearly as this can be determined or estimated from the well logs. The wells are numbered for convenience of reference and are entered according to the formations in which they terminate, those reaching the oldest formations be­ing first listed. WELLS ENTERING THE PRE-CRETACEOUS FORMATIONS As has already been stated, two wells in this area enter the pre-Cretac.:eous formations. The description of the cuttings of these wells will subsequently be published by Dr. J . A. Udden in connection with the destription of samples from other wells in the State. The two wells are as follows: 1. Well on Leon Springs Military Reservation, about 2 miles northeast of Leon Springs Station; elevation about 115 6 ft. above sea level; log made from the driller's records and submitted to the Bureau of Economic Geology by Alexander Deussen. Depth in feet Quaternary: Black soil 0-4 Gravel 4-15 r.1enrose: Yellow limestone . . . . ...... ..... ..... ..... .. ... . 15-25 Blue limestone, a little water ............. ....... . 25-44 15" casing set at 44, Blue clay ........................ · · · ·. · · · · · · · · · 44-50 Blue limestone ..... ... . ... . . ...... . .. ... .. . ... . 50-58 Blue clay ......... . ....... . .... . . . ......... . .. . 58-70 Blue clay and yellow lime mixed ... . .. . ... . ..... . . 70-95 Yellow limestone . . ... .... . ... . ..... . . . . ....... . 95-125 Blue limestone ..... . .......... . ... . .... ...... . . 125-140 Blue clay ............ ......... ... · · .. · · · · · · · · · · 140-155 Gray limestone ..... .... ...................... . 155-160 Yellow limestone .. . .. ....... .. .. ......... . .... . 160-180 9-Bex. University of Texas Bulletin Glenrose: Depth in feet Yellow limestone honey-combed ..... .. ............ 180-l!J9 Blue clay ..................................... 1·99-210 Gray limestone ................................. 210-247 When 600' was reached, water dropped to 300' of surface. Water struck at. 230' appeared to be a strong vein; rose 50' Blue clay . ... .. ... ..... ... .. .. ..... .. .......... 247-254 Gray limestone .......................•......... 254-309 Crystallized limestone ... . ... ........... . .. ..... . 309-3Ui Blue limestone .... . . . .. ........................ 316-366 Gray limestone ..........................•...... 366-375 Hard white crust limestone ..................••..· 375-382 Gray limestone clay in seams .................... . 382-400 Yellow limestone ... ...... .. ................... . 400-433 Blue clay ................................. · .. ·. 433..: 487 Gray limestone ................................ . 487-535 Travis Peak formation: Dark gray sandstone .. ....... .. ...... . ..........0 6 3 5-5 7 0 Blue clay .......... . ......................... .. 670-620 Blue sandstone ................................. 620-690 10" casing set at about 635' Brown stone . ....... .. . ... . .......... . ......... 690-708 Blue stone .......................... ..... . .... 708-775 Blue clay ...................................... 775-790 Red clay ...•................•...•....• .. .•.... 790-792 Brown stone ...................•.......•....... 792-800 Light blue clay ................................. 800-842 Red clay ............. .... ....... . ........•.... 842-847 Blue clay ...................................... 847-855 Green and red clay mixed ........................ 856-865 Gray stone ...........................•........ 866-875 Red clay ........... ... .................. . ..... 876-950 Red clay . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . 950-97 5 Red sandstone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 7 5-9 8 5 Gray sandstone ................................. 985-1010 Conglomerate rock, small vein of water struck.......1010-1015 Pre-Cretaceous: Brown clay ....... . .. .. . .......... . ....... . ....1015-1046 Slate · · · · · · · · · · · · · · · · · · · · · ·. ·. · · ..............1045·-1077 Slate .... · · · · · · · · · · · · · · · ·. · · · .. · · ..............1077-1184 Slate seamed with quartz ..............••...•.•..1184-1244 Slate mixed with quartz .... . .........•......••..12-U-1305 Geology and Mineral Resources of Bexar County 101 Pre-Cretaceous: Depth in feet Slate and oil ............................ . ...... 1305-13'14 Vein opened in cleaning out well. Water rose to 280' of surface Slate mixed with quartz ... .................. . ... 1344-1645 At 1645', casing reduced from 8" to 6". Slate mixed with quartz ...... . ......... . . .... .. .. 1645-2035 At 1728', 8" casing from surface Slate ................ . .. ....... ............ . ... 2035-2500 :No water. 6" casing 2. Well on Camp Bullis Reservation, east of S. A. P. Ry., about 14 miles northwest of San Antonio. Benkendorfer, driller. Eleva­tion, about 1050 feet. Record based on examination of samples by Dr. J . A. Udden and V. V. Waite. The surface exposure at the well shows remnants of the Buda limestone underlaid by the Del Rio clay which is recognized as ex­tending to a depth of 5 3 feet. Beneath the Del Rio is found the thic-k series of Comanchean limestone including presumably the Georgetown, Edwards, Comanche Peak, ·walnut clays, Glenrose, Travis Peak and Basement sands. The Glenrose fossil Orbitulina was recognized in samples from 584 feet and deeper, indicating that the Georgetown, Edwards, and Comanche Peak formations are included in the interval from 53 to 594 feet, or less, from the surface. Orbi­tulina continues to the depth of 1036 feet. From about 1270 to 1770 the cuttings show numero;is layers of blue clay and shale alternating with limestones and marls together with red calcareous clays a:::id shales and some quartz sand this part of the section presumably being within the Travis Peak formation. At 1799 feet and below to the bottom of the well, 1905 feet, the cuttings indicate shists similar to those of the deep well on the Leon Springs Reservation. The formations encountered in this "'·ell may be tentatively given as fol­lows: Buda, 0-14 feet; Del Rio, 14-53 feet; Georgetown, from about 53 to about 95 feet; Edwards, (including Comanche Peak and \Valnut clays if present) from about 95 to 580 feet; Glenrose and Travis Peak (not inclusive of basement sands) 580 to about 1710 feet. Basement sands 1710 to 1790 feet. Below 1790 feet to the depth of the well (1910 feet) is pre-Cambrian schist. With regard to schists Dr. Udden states: The two dark schists seen in the lowest one hundred feet of this boring were carefully tested by J. H. Stullken and found to contain four per cent of fixed carbon, but practically no combined carbon. This fixed carbon is graphite. Tests for manganese were negative. The formation represented is probably the Pack Saddle schist. This well is of especial interest as giving practically the full sec­tion of the Comanchean, and also as indicating the presence of schists beneath the Comanchean immediately south of the Balcones Escarpment. Of the Comanchean formations there is wanting at University of Texas Bulletin this well or.ly the upper part of the Buda. The actual thick­ness of Comanchean drilled through is 1770 feet. To this should be added about 50 feet to account for the fu!J thickness of the Buda limestone. Thus the Comancbean at this locality is about 1820 feet thick. Log of well at Camp Bullis Reservation, San Antonio, Bexar County, Texas, August, 1919. Furnished by F. G. Chamberlain, Constr. Q-M., Camp Travis. Buff colored limestone ................ .. . . ..... . 0-7 Buff colored limestone, lighter than above ... .. . .. . . 7-14 Buff colored marl . ........... . ................ . . 14-38 Yellow marl . ........... .. . ... .. .............. . 38-50 Yell ow clay . . . . .... ... ............. .... ....... . 50-53 Straw colored limestone ........................ . 53-65 Yellow limestone, fine texture ....... . . : .. ........ . 65-li8 White limestone . ...... . ..... . . .. . .. ........... . 68-72 Yell ow limestone ..... ... . ...... ... ............ . 72-78 White limestone ..... . .... .. . . ................. . 78-89 Cream colored limestone ........... . ........... . 89-93 White limestone ....... ......... ...... . .. .. ... . . 93-113 Cream and light gray limestone .. . . . . . . . ........ . 113-118 Light gray limestone with gray flint ..... .. . ... .... . 118-124 Cream and light gray limestone . . .... . . . .. . .... .. . 124-129· Compact gray limestone . .. . .... ... ... . .... . .... . 129-146 Cream colored limestone, some flint .. .. .. .. . . . ... . 146-158 Cream colored ·and light gray limestone .. . ......... . 158-170 Compact cream colored limestone ......... . .. .. .. . 170-186 Cream and light gray limestone . .. . .............. . 186-194 Cream colored and some yellow limestone . ... . .... . 194-197 Grayish white limestone . ....... . .. ..... ... .... . . 197-207 Compact cream colored limestone ....... . ........ . 207-221 Light cream colored limestone ... ... .. . . .. ....... . 221-230 Yellow foraminiferal limestone ........ ....... . . .. . 230-232 Yellow limestone red blotches .......... .. ... . ... . 232-237 Yellow and gray limestone, red streaks ...... ....... . 237-244 Blue limestone ... .. .. ... ................... . .. . 244-246 Bluish gray limestone . . . . ....... .. ............. . 246-255 Yellow limestone ........................... . .. . 25 5-260 Yellow and gray limestone . ........... . . ........ . 260-277 Yellow limestone .. . .. ................... . ..... . 277-288 Yellow limestone and light gray sandstone ..... .... . 288-292 Light gray dolomite ... ... .................•..... 292-302 Gray limestone ............... .. ........... . ... . 302-315 Gray dolomite ................................ . 315-325 Gray limestone .. ......... . .................... . 325-331 Dolomitic gray limestone ... .. .. . ............... . 331-348 Geology and Mineral Resources of Bexar County 133 Oolitic foraminiferal gray limestone ... ... .... . ... . 348-352 Gray marly limestone ....................... .... . 352-360 Gray impure limestone ........ ... ... . ..... . . ... . 360-387 Gray fine grained limestone ... .. . . .. ... ..... .. . . . 387-392 Light blue gray limestone ............ . .. . ... .. . . . 392-397 Fine-grained gray limestone ... . . . . . .. . ... . . . .... . 397-415 Gray soft marly limestone .... .................. . 415-456 Gray oolitic foraminiferal limestone ...... . . .. . . . . . 456-472 Gray marly limestone ..... ..... . .. . ... ... . . ..... . 472-49 3 Gray soft organic limestone ..... . .. ... .......... . 493-515 Gray dolomite, limestone, some shale .......... ... . 515-520 Gray foraminiferal limestone ......... . . . ........ . 520-530 Gray dolomite, limestone, some quartz sand . . . .. .. . . 530-535 Gray organic fragmental limestone . . ... ... ....... . 535-608 White foraminiferal limestone ................... . 608-612 White fine-grained limestone .. ... ........ . .... ... . 612-617 White porous organic fragmental limestone ..·...... . 617-626 White limestone, some quartz sand ....... . ... . .. . . 626-630 Light gray foraminiferal and organic fragmental limestone ..... . . .. .......... ..... ....... . . . . 630~ 641 Gray limestone, some bluish gray marly shale ..... .. . 641-646 Gray limestone ......... .... ....... . .......... . . 646-655 Fragment of stalactite ....... ..... ....... .... ... . 655-660 Gray foraminiferal and organic fragmental limestonE.' .. 660-679 Gray marly limestone and bluish gray marly shale .... 679-6S::l Light gray foraminiferal and organic fragmental limestone ...... . . .. . .............. .. ....... . . 683-707 Bluish gray marl ............ .................. 707-73i Light gray marly limestone ..... .. . . . .. . ....... . .. 737-743 Light gray limestone ............... ............. 743-1090 Gray limfstone . .. ........... . .... . . .. . . ... .. .. . 1090-11 00 Dark gray limestone ......... . .. ... . ..... .. .....1100-1112 Dark gray limestone and gray marl . . . .. ... . .. ..... 1112-1119 Gray limestone and white marl ... .. . ... . .. . ......1119-1120 Gray limestone and gray marl ... .. ............... 1120-1125 Gray limestone, organic fragmental . . . ...... . . .....1125-1144 Gray limestone, some gray marl . ...... .. .. .. . . ... 1144-1150 Dark gray marl and some dark gray limestone ...... . . 1150-1161 Gray marl .... .... . . ..... .... . ........... . . .... 1161-1167 Gray limestone, white limestone, blue marl .......... 1167-1173 White and dark gray marl, some yellow limestone ... . 1173-1179 Light gray limestone .... .. . .. .. . .... .... ... .... . 1179-1186 Light gray marly limestone ....... ... ... ..... . .. . 1186-1209 Blue and white marly limestone ........ ........... 1209-1219 Light gray marly limestone .................. .. ... 1219-1232 Gray and cream colored limestone .. .... ... .. . ... .. 1232-1240 University of Texas Bulletin Greenish gray marl, some fine gray sandstone..... .. . 1240-12 47 Light gray and marly limestone .. .. ................1247-1253 Light blue marly clay .................•.........1253-1255 Fragment of echinoid spine, cytherea ............ . . 1255-1258 Gray limestone .. . .................... ..... .....1258-1259 Light buff colored limestone, some marl, pyrite and sand .................. .... ..... .. ... .. .. 1259-1262 Gray marl .....................................1262-1269 Buff colored limestone, gray limestone, gray marl, some calcite, sandstone, and chert ... . .. .... .... . 1269-1270 Blue and white marl ............................1270-1279 Light blue shale, some white marl .. ... ... .. . ......1279-1284 Blue marly clay ......... .... ........ .... ....... 1284-130:! Dark gray organic fragmental limestone . . ..........1303-1310 Blue marly shale, some white marl and fine buff colored limestone .............................1310-1316 Blue marl with gray limestone ....................1316-1322 Blue marly shale ... ... .... ...... . . .............1322-1334 Dark gray organic fragmental limestone . . .. .. .. . ... 1334-1345 Gray organic limestone .. ._ . .. ... .... ...... ..•... . 1345-1475 Blue marly shale, some quartz and sand .............1475-1479 Blue marly shale and some gray limestone ...........1479-1484 Blue marly shale and some sand .. .. ...... . . . ... . .. 1484-1501 Soft blue marl ... .......... . .... .. .. . . ... ......1501-1528 Dark olive green and some light gray marl. . . .. .... . 1528-1533 Bluish green marl and some light gray marl. . ..... .. 1533-1539 Bluish gray marl, some marly shale, and quartz ..... :1539-1549 Blue marly shale ......................... '. ..... 1549-1623. Soft blue calcareous shale ........................1623-1625­Light red rnarly shale ........... . . .. .... . .......1625-1647 Soft light green marl ............................1647-1654 Bluish gray marl .. ........ . .... .. .. ...... .... .. 1654-1657 Brownish gray marl .............................1657-1660· Light gray marl ............................... . 1660-1666­Light greenish gray marl . .................. .. ... 1666-1673 Light brownish colored marl, much sand ..... , ......1673-1675. Light brownish colored marl and less sand ...........167-5-1689 Light colored marl .............................. . 1689-1703 Light buff colored siliceous limestone ........... ......17 03-1711 Ligh.t buff colored calcareous sand ... ....... .. .....1711-1766 Light buff colored limestone with fine and coarse sand . 1766-1770 Dull yellowish gray schistose shale .............. ... 17 7 0-177 9· Yellowish gray schist, part purple .................1799-1802 Dirty brownish gray and bluish gray schist . . ...... .. 1802-1808 Dark and light brownish gray schist ................1808-1816 Slightly micaceous schist, white and gray quartz .. .. . . 1816-1822: Geology and Mineral Resources of Bexar County 135 Dark gray schist, some quartz ..... . .......... .. ... 1822-1830 Dark gray, dull red and purplish schist, some quartz . . 1830-1835 Dark gray schist, some greenish and reddish ......... 1835-1847 Dark with little pinkish gray schist ............ . ... 1847-1856 Dark gray schist with reddish and light greenish gray .1856-1869 Very dark almost black graphitic schist ..... ........ 1869-1875 Schist, dark gray, reddish, and greenish gray ..... . .. 187 5-18 9 5 Like preceding but more green . ..... . ............. 1895-1900 Blackish gray graphitic schist, some quartz ..... ..... 19 00-1910 WELLS TERMINATING IN THE COl\IANCHEAN The term "non-flowing" is used for wells in which the \Yater rises in the boring but does not reach the surface. ''Flowing'' wells are those in which the water overflows at the surface. The head of the water above or below the surface is given for some of the wells; however, the head varies considerably, as already stated, with the season, and the record for any well is likely to vary according to the season in which the measure­ment was made. In the well records, the follo·wing data are given in order, so far as available: Name of owner; location of "·ell; depth; elevation at the well; water, whether flowing or non-flowing; elevation of the top surface of the Del Rio formation above or below sea level. These data are followed b~-the log of the well if available. The approximate location of most of the wells is indicated on the contour map by the entry showing the level of the top surface of the Del Rio formation. ·with the elevation of the top of the Del Rio recorded, the level of the other Comanchean and Cretaceous formations can be approximately determined. The top of the Comanl'hean (base of the Upper Cretaceous) lies about 65 or '70 feet higher than the Del Rio; the Georgetown-Ed"·ards series of lime­stones. the principal water resenoirs of this county, lie im­mediately below the Del Rio or about 70 feet lower than the eleYation given. The Upper Cretaceous formations are 1200 or 1300 feet thick. An asterisk placed after the number of the well in the table indicates that a log or other data are given following the tabulated record. WELLS '.l'.ERM.l.NA'l'ING l.N 'l'HE OOMANOJi.EA.N \LOWElt Lilth'1'A01WUl:!J FORMA'1'10.NI:!. ~·~~~~~~~~~~~~~~~~~~--,-~~~~~~--~~~~~~~~~~~~~--,~~~~~~~~~~~~~~~~­ Location with Reference to :>an Antonio Court· Owner Water .'.\o . house I Depth I Elev. 3*1 Ackerman, H. J .•.. 6 miles ea•tt----------------1 1400 Acme Irrrgatfon Co. N. E. of Kelly Fieldt----­s•I Alamo Waterworks_. Alamo Hei&hts ..____________ !)•I Allen, D . J .--------­ 8 9 10 11 12* 18 14* 15 16* 17 18" rn• 20 21* Allen, D. J ·-------· Artesian Ice Co .••-. Artesian Water Oo. Altgelt, E . J ________ Altgelt, E. J ·------Basse, Ed. E,_____ Bayean, Gu•-------- Beneke, Mrs. Kate__ Benz, H.------------· Blerlng, ·u. T.------Bexar CountY------­Blank, J. T-----­Blue Wing Olub-----Baerman, A, ________ Boerman, D.------­ Kelly Fieldt ---------------­South of Kelly Fieldt----­8/17 Avenue Bt-------------­4 miles southt-------------­10 miles notht-------------­ gJA, miles northt----------­6 miles northt-------------­Cupper's Lane______________ 22 mlles northwestt-------­S miles northeastt---------­ 15.6 miles northwestt------Courthouset --------------­ 6 miles westt-------------­12 miles southt-------------­ 10.5 miles northwestt------­11 miles northwestt-------­ 1480 640 1006 1488 1006 866 660 500 1146 1000 1500 850 872 1483 2440 351 «XI 6651 Non-tluwfug 685 816 6BO 662 660 678 1000 1000 760 685 1030 696 960 666 710 490 815 880 Non·ttowing Non-ttowing -149.•• Non-flowing -6_____ Flowing Flowing Flowing +10________ Non-flowing Non-flowln& Non-flowing Non-flowln& -------­Non-flowing --300... Non-ttowlng ~---­ Non-flowing -278..-­ Flowing +20-------­Non-flowing -47____ Flow. sul1>hur water INon-flowing Non-flowing -178... Depth of Del IElev'tlon Rio frorn Sur- Top of face Del Rio gso-1000 -285 996--1046 -310 885? 430-500? 1000-1064 ---940 150 306 889-'46 950 At surface 6 6l50-700 1163-1228 -453 -1685± 2HO­ 645 270-330 660 320-386 Marine Formations Penetrated I 'J'uyior to Edwards. I Taylor to ~;dwards. Austin to Edwards. Navarro to Glenrose. Navarro to Edwards. 'l'aylor to Comanchean. Navarro? to Edwards. Austin to Comanchean. Austin to Oomanchean. Taylor? to Edwards . Navarro to Georgetown. Taylor to. Edwards. Austin to Glenrose. Del Rio to Edwards. Taylor to Edwards. Navarro to Edwards. Wilcox to Edwards. Austin ta Georgetown. Austin to l<~dwards. ,..­ .:...:. O'l C::::J e~ · ('> ~ ........ <.:: ~ "-3 ~ fl b;i ~ ~ .... ~· 22 IJrntly, '1'. F . ______, Oervalo streett-------------1 1600 23 IJrackcnrldge, (',-co. -Northeast of Country Clubt 1018 1 527 IJnnclera Streett________ ,_______ _ 24• llrendle, IL--------­25 I Bruhn, H·----------1 8 miles north!-------------­ 660 26 I Carney, Glen_______ _ 1226 21•1 Clump. 0. o. _____ .I G miles west! miles enstt---------------­ 1452 28'1 <:olllns Mfg. 00.----1 'h 111ilo northeastj__________ ___ ____ _ 29 OolhnH , F. F. ____ ___ Snn Antonio___ __ ___ __ ___ ___ 006 30' 1 Collins Garden"-----1 Southwest! 31 I Comrmmlty Well____ I Cupper's Lanet-------------1 1005 1 32 1 Davis, Hcss---------·15 miles northl--------------1 568 33* Dickenson ___ _________ smiles west!---------------­ 602 34 Doboralski, Wm. ___ I San Antonio----------------! 1405 So EdgewoodWaterCo. Edgcwr orl, San Antoniot--i 1005 36 Electric J.lght. Co. __ San Antonio. ___________ ____ 1 1000 371 Epps, J .J·----------1 Frio rc a 8()0 008 630 720 1010 650 700 660 660 650 685 750 850 670 68() 620 665 700 850± 000 675 666 Non-tlowing -·&---' Flowing +34_______ _ Non-flowing Non-flowing Flowing Non-tlowing -24-__ _ Flowing ------------i Flowing +28___ __ ___ , Flowing ------------, Non-ttowlng, near I surface. -----------1· Non-flowmg -------­Non flowing -18()__ _ Flowing?. ---·-------! Non·flowing --------, Flowing +42__ ______ I I± I Non-llowlng -13---­Non-nowing --------1 Non-flowing -27____ Non-tlowlng ________ J I Flowing + 20 ________ 76<>-800 640-685 4X--583 300-400 1600± 1110-1162 720-800 840-890 930-1000 930--905 50<>--665 497-567 99&-1049 925-975 838--900 830-880 1000-10'.>0 352-408 102!1-1084 650-700 675-725 I Non flowing -330___ 444-604 43' IGoforth, A. E. -----118 miles northwest!-----·_ 940 664 Non-flowine-418-494 44" <10\'rrnmcnt Wf'JL ___ At A.vlution postt---------· 874 736 -& 90 227 620 -8502 --410 -60 -180 --280 -245± 250 353 -325 -245 -218 -165 -300 Taylor to Glcnrose. Taylor to Edwards. 'l'aylor? to Comanchean. Austin to Edwards. Navarro? to Edwards. Navarro to Edwards. I'J'aylor to Comnnchcan . Taylor to Georgetown. Taylor? to Comanchenn. Taylor? to Georgetown. Taylor? to Georgetown . '!'nylor? to Georgetown. Navarro? to Edwards. Navarro? to Georgetown. Taylf'f to Edwards. Taylor to Edwards. N'avnrro to F.tlwards. 498±1 Austin to Edwarcls. -339 25 -10 4116 317 Navarro to Edwarcls . I Taylor to Comanchean. Taylor to Edwnrcls. Austin to Edward•. Taylor? to Eclwaril•. q) c "' c ~ <:<::: ::; '""' ~ ~ ~· ~ g_ "' ~ c "' ~ "' ~ "' c -.... O;j "' I':> "' 'i C':l c ~ ;;> ,,.;.. ~ ...... C>:i -1 No. I Owner 45'1 Government 46*1 Grote, 'F·-----------· Gunter HoteL______ 48 Haag's Store________ 49' Harrison, Jud_______ 50 Hartman, Paul-----­ 51 Hearne, ROY-------­ 52 Hearne, Roy________ 53 Hearne, ROY-------­ 54 Heine, H-----------· 55 Hense, Chas. ________ 56' Herff, H.____________ 57•· Hill & Roby________ 58 Hoffman, Mrs. c. __ 59* Hofheintz, R. H.-­6()* tioltz, Wen__________ 61 IHooge & Waters____ 62 1 Hornenberger________ 63" Hot Wells HoteL___ WELLS 'l'ERMINA'l'ING lN THE COMANCHEAN (LOW1m CHE'J'AOJ•:OUS) FORMA'l'IONS-Contlnued. 1--" I Location with Reference to San Antonio Court· house I Depth I Elev. Wen___ I~-----------l Hackberry St. near Ave. Ctl 6 .5 miles northeast!-------­Houston and St. Mary sts. &14 miles north____________ 8.5 miles northt----------­9 miles-westt--------------­Alameda Gardens!--------­ % rnile northwest No. 5lt 1 mile west of No. 51t-----· 11.5 miles westl----------­9 miles westt--------------­ 4.5 miles west!-----------­ 7.5 mllc.s south!----------­19 miles northwestt--------­North of Kelly Fleldj_____ 9 miles southwest!---------Zalzamora and ·Laredo sts. ---l---I 729 I 339 1018 325 328 680 1200 745 809 715 620 1200 1800 736 1458 1665 1475 , 9 mil~ northwestl--------1--------1 4.5 miles southL----------­ ·------­ 689 840 653 845 900± 770 73() 740 739 710 770 682 625 !Y75 680 610 650 Water Non-flowing -3----­Non-flowing -159__ _ Flowing +24-------­Non-flowing -------­ 870 INon-flowing 575 Flowing I Non-flowing -80---­Non-flowing Non-tlowing -76____ Non-flowing -86---­ ?______________ ______ Non-flowing -SQ____ Flow. sulphur wate1 I Non-tlowlng -315___ ?-------------------­I Flow. sulphur water! I Flowing Depth of Del IElev'tlon Rio from 8ur· Top of face · Del Rio 620-673 I 69 272-332 568 675-725? -22? 24~ 600? 245-300 655± 560-620 210 700-750 30 620-670 120 513-575 226 595-655 115 500-566 270 1100-1155 -418 1695-1750 -1070 606-666 369 995-1049 -315 1525­ -915± 950-1000? -300? 400-470± 470 1445­ -870 c.:> Marine Formations Penetrated Taylor to Edwards. Austin to Georgetown. Taylor to Edwards. <::::! Austin to Edwards. ~ ~· Austin to Georgetown. ('> ~ Taylor to Edwards. ~ cs:: Taylor to Edwards. ~ Taylor to Edwards. 1-3 Taylor to Edwards. ('> !:'l !;> Taylor to Edwards. "' b:;j Taylor to Edwards. ~ Navarro to Edwards. ('> <-;.. Tertiary to Edwards. ~­ 'faylor to Edwards. Navarro to Edwards. Tertiary to Edwards. Navarro to Edwards. Austin to Comanchean. Tertiary? to Oom11nchean. fil I I111hh!P, I.. M . . ();-, h·all~RUII, ~ ·-- Lli IJ\PUrlH'.Y, c. IJ. ... •• I li7 ' 1\Parrw.v 0. & P. L.1 ( ·ornpnny. fi ·.: h:irln1atri1·k, .r. JI fi() l\:n•llH'll , .J 01~ I 7<1 I l\rn·p~, A 'ii I h:n~11t1·li, ().-;1·ar . .. ---­7:! I Ludy of LHke :\cud. 73* 1 _l.nlrn Vi<~\\.. Add It ion 7-1"'1 l.1•glcr, W . Ji'. _______ 'iii~! ·r.ocke, 70 Lonr. St1tr BrPwing Company. 77'· l,ort' rll., Aif'x __ __ __ __ _ 78 !\'lu cl ntosh, MrR----­7!1 .Mnlo11e, W. D. _____ sn· J\1astrrson, B. F, ___ HP 1\fnlyrar, CllflR . .... .. . fl2"' 1\-frdi na "Jl111ll r rs Earth CPrnpan y. s:~.. I :\frO 23!)!) 610 f~O 1105 (J40 ():20 7!il 1000 (i7!i 13.~0 Gsri 5UJ 678 I 1G:i5 I OO!l i ~~Oj:-; 7'.0 ! 80!") f,CO 420 8.10 C()8 700 ]!}00 fi72 1620 750 t10fl 678 778 770 1~.1~ !'i,1(} f.80 7.riS m1 r.4~ 784 Non·Jlowlng f\on flowing -.:j;ro__ Flow. ~11Jpl111r \\-'U.I 1•r J1'low . ~ulphur \Vat(ff 11'Jowi11g Flowing +10___ ___ _ ~Ofl· llO\'i-"iflg' --8()___ _ l Non.flowing 7___ ··-i \'on-flowing 2fi. __ _ \"ot1 -flowh11!' Nf'n flowing --·20 ___ ; Non-flowi ng --!J!L __ _ l_i1J<>Wing N'on-llowing ~('n.flowing ... .10__ _ !\'( ·n -flowing­ No11-f1nwing --«----­ Non-flowing Flrnv . . c;11 Jph11r wnt.r.r 1\'on -Jlt1wi11g -------­ Ji'Jowing __ , ___ __ __ .. _ :\'on -flnwing -JJ!)___ 1 cu "' 0 0 'Cl <.:: ;::, ~ R. i:::: ~­ "' ~ "' ~ "' "' 0 ~ "' 0-"' b;j "'1-l ;::, "i ("'.) 0 ,...._ - "' ·-' ~.') >:.o !\.11'rlf'hll('l\ Str1~!tf --------j rn 111iks nortlrn1Nlt.L-------! I .• rnik1-1 l!ltl:i\.f ______ ____ _____ 12 111llrt' soul.hf_ _____ ____ __ _ 1 So11tl1\VP1-il.'? ---------------' i sy-,:,-j;,... -:,-•.: ; ;,~:~:;;: : :: ::: :: I !1.:·1 111ikR (~nstf. _____ . __ ___ j Wt•,t rity 1i111its·t----------j ~Hh ~\1Td____ ·-··------··----1 r, milt•s w~stf_ ________ ----·· 1 !5 mflr.~ nnrtht -------·------! 1 ~0 .J nn<'S Avr1111rt_ ___ ___ __ ! r, 1 11:ir~ northL.------.. ­ i 7 rnilr~ rnst+-----.. ---------: \VP~t Oity litnlt~----.. -----1 I lR mf11•R wr~tt... _____ -----I I ·?1111 ~ lrPf't. :tnd J;:ikrvir.w · ; 1() mi\11~ W<'Rtt-.. . --·-------· ...... WELLs '.l'ERMINA'l'ING IN '.L'HE COMANCHEAlll (LOWER CRE'l'AQEOUS) ~'OltMA'l'IONS-Continued. >l­ o Depth of Del IElev'tlon Marine Formations L6cation with Reference Penetrated house l Depth I Elev. Rio from 8ur­ 'l'op of Water to San Antonio Court-Owner :. I San Antonio Steam 131 North StrcctL---------Launrlry. 100 I Snn Antonio Street! JOth 8trcct and Ave. D-­ 107' 108' 10 mile wr.<1tt-----------­Dnrnn!(o nn<>± 1000 672+ 813 1050 400 1185 758 1840 1185 740 660 mo 830 700 ins 810 655 750 708 750 1040± 680 800 645 645 660 630 I 620122 1Snllivnn, D-----------11\6 mile S. l'-t-------------, 1100 123' Superior Oil Co.___ 12 miles southt--------------------612 124'1Terrell Hot Welt~---5.2 miles soul.ht-----------1956 630 \ Non-llowfng --:7Q____ , I Flowing ------------1 1-------------------­ Non-llowlng -------­Non-flowing -------­? -------------------­ Non-flowing -135 ___ Flowing -----------­Non-flowing -------­Non-flowing -------­ Non-flowing ------­ Non-flowing -330___ Non-flowing -3()__ _ Non-flowing -l{l()___ Flowing -----------­+18_______ Flowing Flow. sulphur water F lowing sulphur +44-___ ____ water I:::':~Ip~:::-;:~~:~ Flowing ____________ ; 587-!567? I l&H I '.l'ayJor t.o licorgclown . 77:;-825 800-850 200-330 32:;-375 789--856 640-700 0 600-711 400-400 620-672 620-672 673-753 441-494 308-300 983-1041 6S2-734 1790-? 983--1041 975--1040 1500­1380-142& I -115 -130 670 435 -120 1'/Q 5 350 88 82 367 239 492 -338 -32 -1130± -353 -355 -888 -750 i T11ylor to Comunchcan . Tnylor to Edwards. 0 "' ~ AuHtin to Georgetown. ..... 0 :> Taylor to Comn.nd1can. ;:S R. 'l"aylor to Gcol'gctown. ~ Taylor to .Euwards. ~· Allstin to Oomnnehcan . "' ~ Taylor to Erlw11rcts. ~ ·ruylor to J~dwnrrls. "' 0 "' ~ 'l'uyfor to EdwnrI'" ,_. Tertiary to Comanche an. WELLS 'l'ERMINA'l'ING IN '!'HE 00.MANOHEAN (LOWKl:l. L:ll..E'l'AO.EOUS) .l!'Oll.MA'l'lONS-Oontlnued. ...... No. I Owner I 125*1 'l'errell, Dr. J. li,__ 126 rn7" 128 129 130 131 132' 133 134 135* 136 137* 138* 139* 140 141 142 143 ~ Tex. Steam Laundry 'l'ezel, Loufs ________ Tczel, Pete----------Obas.________ Tezel, Toft, L. 8---------· Tommlns, R.-------· Townslte Well_______ '!'rice, G. F.------· Vhl, H.-------------· Union Meat CO----­Van Dale, H·------- Voght, Wm.-------- Voight, A-----------· waring Estate______. West Gardendale____ Widener, J----------· Wier, Chris--------­Winter & Kreugel--c Wurzb~ch, O. J ____ Lh Streets_ Parr111l and Brazos Streets 14 miles southwestt-------­14 miles uorthwestt-------­ 7 .5 miles .northwestt------­·5 miles westt--------------­17 miles northwcstt-------­14 miles northeastt-------­9%. miles south!----------­n miles northwestt--~----­Dep.th Elev. ·--­ 114-0 675 748 665 245 866 825 210 235 815 1260 666 1500 630 2320 600 1449 675 675 1010± 1400 640 955 640 1850 606 216 850 2853 920 1284 710 533 970 870 1825 595 620 960 I IDepth of Del IElev'Uuul Wa1.tJ1 Non-tlowlng -------­Flowing +28 ------­Non-.tlowlng -------­ Non-tlowing -15() ___ Non-flowing -------­ Non-tlowlng ?------­ :t.'lowlng Flowing -----------­Non-flowing -12---­Non-tlowlng -aso___ Flowing +so________ Flowing -----------­ Flow. sulphur water Non-flowing -177.. Ncn-flowing -46____ Non-tlowlng -------­ Non-flowing -280--­ Non-flowing -190___ Flow. sulphur water INcn-Howlng -260___ Marine F·ormatlous .PeuetraLed Navarro to Edwards. Taylor to Georgetown. Austin to Georgetown. Austin to Georgetown. Austin to Georgetown . Navarro to Edwards. Navarro to Edwards. Tertiary to Edwards. Taylor to Glenrose? Taylor to l'.'1wards. Taylor to Glenrose? Taylor to Edwards. Tertiary to Edwards. Austin to Georgetown. Taylor to Travis Peak. Navarro to Edwards. Austin to Edwards. Austin to Oomanche11n. 1'ertlary to Glenrose. Austin to F.flwar ~ "'!:-l i:l "" -..... ""' ..... "'.,... ~· ltio from Sur­face 99S-1068 645-703 160-210 140-200 120-180 107<>-1125 1810-1370 2030-2100 775-825 555-615 751-820 750-800 1485-1587 120-180 460-510 1125-1184 415-475 400­ 16-00-1669 440-500 'l'OP of lJel Rio -323 20 715 685 695 -406 -680 -1S80 -100 455± -111 -110 --880 730 460 -415 555 470 -1005 I 520 *Log or other additional record given below under the heading "Supplementary Data." tLocatlon Indicated on contour map. Geology and Mineral Resources of B exar County 143 SUPPLEMENTARY DATA ON WELLS' TERMINATING IN THE C0?.1ANCHEAN The following data including logs is supplementary to that given in the preceeding tabulated records. 3. H. J. Ackerman, 6 miles east of San Antonio, east side of the W. W. White Road, 1h mile south of St. Hedwig Road. This well is near the limits of the area of surface flow from the Georgetown­Edwards limestones. 'Vhen first drilled, the well is said to have flowed slightly over the pipe but to have subsequently ceased to flow. The well is also near the south iimits of non-sulphur water in these lime~tones. 5. Alamo Water " Torks, Alamo Heights. Lorenz Bros., drillers. Log by dri!Jers from memory. Yellow clay (Austin?) . . . . . . . . . . . . . . . . . . . . . . . . . . . 0-140 Yellow rock (Austin) . ....... . ......... ... .. . ... 140-350 (First) mud hole (Eagleford) ............... .. .. .. . 350-380 White rock (Buda) ..... .... ....... . .. .. . .. ..... 380-430 Dark blue mud, caves (Del Rio) .. . .. . .. . ... ....... 430-500 Yellow sand rock (limestone?) ...... .. . ..... . .. .. . 500-54 0 6. D. J. Allen, in Kelly Field south of Pearsall (Frio) Road, 1 mile S. W. of city limits. T. H. Little, driller, 1910. Gravel and yellow clay (Pleistocene) . . . . . . . . . . . . . . 0-60 Shale (Taylor and Navarro) . . . . . . . . . . . . . . . . . . . . . . 60-600 White limestone (Austin) .... ..... ... .... ........ 600-900 Lignite of shale (Eagleford) . . ...... ............ . . . 900-940 Hard rock (Buda) . . ..... . ... ................ .. . 940-1000 :Mud hole (Del Rio) .. .. ... . ....... . .............1000-1054 Brown and white limestone .................... .. 1054-1254 White and gray limestones ..... . .. ...............1254-1 595 The gravel deposits of this well are those of the Pleistocene. Aside from these flood-plain deposits the materials to the depth of 600 feet represent the Taylor and a part of the Navarro. The Austin formation is recorded as "white limestone," 600 to 900 feet. The Eagleford, "lignite" is given as 40 feet; the Butla, "white rock," 60 feet; and the Rel Rio "mud hole" as 54 feet. The top of the Comanchean was reached at 940 feet. The water-bearing limestones were here reached at 1054 feet and were penetrated to 540 feet, thereby securing a very large flow of water, the well being re­ported to yield 3000 gals. per minute by pumping. Mr. Allen has several other similar wells on this property. 12. Ed E. Basse, west side S. A. & A. P. Ry., south side Olmus lH University of Texas Bulletin Creek, 5 miles north of San Antonio. Alex Lorenz, driller. I.og by driller from memory. Surface materials . .. ..... . ........ . .. . . .. .. . .. . . o. 30 Blue mud, thickness not recorded.: ............... . 30-425 Lignite (Eagleford) ............ ....... ...... . . . . 425· 450 Not recorded (Buda) ... ................ ........ . 450-500 Clay (Del Rio) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 500-555 Limestone (Georgetown) . . .. . . ................. . . 555-590 14. Mrs. Kate Benke, north side of Culebra Road near the west county line. A. E. Goforth, driller. Log by driller from memo1y. Yellow clay and rock (Taylor) . . . . . . . . . . . . . . . . . . . . 0-300 White magnesian limestone and blue medium hard limestone (Austin) .. .... . . ...... . . .... ..... . . 300-785 Lignite (Eagleford) ............. .................. 785-820 Buda limestone .... . . ... . . . ............ . . . . . ... . 820-880 Clay fDel Rio) ............ .......... .......... 880-940 Limestone (Georgetown-Edwards) ... . .. . .. ........ 940-1000 Although located within a mile or so of the Balcones Escarpment, the first 300 feet of this well with little doubt pass through the Taylor formation. This is followed b.y 485 feet most or all of which Is to be referred to the Austin, representing the thickest recorded section of that formation. The Eagle.ford is assigned the usual thickness of 35 feet; the Buda, 60 feet ; and the Del Rio 60 feet. The top of the Comanchean formations lies at the depth of 820 feet from the surface. The magnitude of faulting in this area is indi­cated by the fact that within two miles west from this well the Glenrose formation is seen lying at the surface at elevations of from .1200 to 1400 feet above sea level, while in this well the top of the Glenrose probably lies 300 feet or more below sea level. 16. H. T. Biering, west side Bandera Road, 15.6 miles from San Antonio. Record from owner. This well is located in the Del Rio plain a mile or so from the Balcones Escarpment. The surface materials at the well are heavy stream washed gravel, although the Del Rio nearby lies at about the same level. The well starting at the Del Rio level terminates in the Edwards limestone. 18. J. T. Blank, south side Castroville Road, 6 miles west of San Antonio. Surface materials; blue clay and rock . . . . . . . . . . . . . . 0-928 Not recorded .. .. ............. . ............ . .. .. 928-1163 "Mud hole" (Del Rio) . . ........ .... •..... .... ... . 1163-1228 Limestone ........ . . . ..... . ...... . .. . .. .. . . ....1228-1483 The principal water supply is reported to come from only 4 feet Geology and Mineral Resources of Bexar County 145 below the surface of the Georgetown-Edwards limestones. Above this level are the formations of the Upper Cretaceous, t·he Eagle­ford, Austin, Taylor, and probably a part of the Navarro. The sur­face materials here are the gravel flood plain deposits. 19. Blue wing Club, west side of San Antonio River, 12 miles south of San Antonio. Drilled by cable. Jacob Wolf, driller. Show­ ings of oil at 900 feet, and continuing more or less to 1200 feet. Sand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5 Clay, yellow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-85 Sand, white, with water . . . . . . . . . . . . . . . . . . . . . . . . . . 85-90 Rock, hard, blue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90-92 Clay, soft, blue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92-112 Rock, hard, blue ................. ............. . 112-115 Clay, soft, blue ....... ..... .......... ...... . . . .. 115-133 Rock, hard, blue ........... . ... .. .......... .... 133-135 Clay, soft, blue ................................. 135-150 Rock, hard, gray ...... .. ......... .. ... . ........ 150-153 Clay, soft, blue .......... . ............. . ... .... . 153-170 Rock, hard, gray ............................... 170-174 Clay, soft, blue ................................. 174-191 Rock, hard, blue ................................. 191-193 Clay, soft, blue ........ . .......... . .... .. ....... 193-211 Rock, hard, blue ...... .... . ... .......... .... .. . 211-215 Clay, soft, dark blue ...... ... .. . ... .. .. .. ..... . . 215-231 Rock, hard, dark blue ..... .. .. . .......... ... ... . 231-234 Clay, soft, blue ....... ..... ... . ................ . 234-250 Rock, hard, gray ............. .... . .. .... .. ... .. . 250-252 Clay, soft, blue .. .................... . ... .. ... . . 252-270 Rock, hard, gray ...... . .. .... .. ........ ... ..... . 270-273 Clay, soft, dark blue ... . ........ .. . ..... . . .. ... . 273-289 Rock, hard, blue ............................... . 289-293 Clay, soft, blue .. . ... . ... . ... ... ......... ... ... . 293-311 Rock, hard, blue .... ... ...... . ... . ........ · ... · · 311-313 Clay, soft, blue ............................... . 313-320 Rock, hard, blue .. . ..... .. ..... . .......... ..... · 320-322 Clay, soft, blue ................................ . 322-334 Not recorded .... . . ... ..•...... ... . . ........... · 334-337 Rock, hard, blue ... ... ..... . ............. .. . . . . 337-357 Clay, soft, blue ................ .... ............ . 357-360 Rock, hard, blue . .... . ......... ... ......... .... . 360-383 Clay, soft, blue .... .... ....... .. ...... .... . .. .. . 383-387 Rock, hard, gray ............................... . 387-405 Clay, soft, blue ....... . .................... ... . . 405-407 Rock, hard, blue ..... .. . . ...... ... ......... . ... . 407-425 Rock, hard, gray .... . .. ........ ............. . . . 425-428 10-Bex. University of Texas Bulletin Clay, soft, dark blue .•.••....................... 428-H5 Rock, hard, gray ............................... 445-447 Clay, soft, light blue .................•.•....•... 447• 460 Rock, hard, gray .....................•......· . . . 460-464 Shale, soft, blue ..•••....•.•...........•........ 464-468 Rock, hard . gray .....•••...•..••.........••....• 468~ 470 Shale, soft, dark . • . . . • . . . . . . . . . . . . • • . . . . • • . . . . . . 4 7 0-4 7 2 Rock, hard, white ...•..•....................... 472-478 Shale, soft, dark blue .....•••....•••............. 478-567 Rock, hard, blue ..•.......••................... 567-569 Shale, soft, blue .................•......•..•.... 569-728 Shale and boulders, soft, blue ..................... 728-755 Shale, soft blue ........•........................ 755-905 Sand rock, soft, gray ........•••........•........ 905-925 Shale, soft, blue ............••••..•.•........... 925-960 Shale, soft and hard, blue ..•.••...........•...•.. 960-996 Rock, soft, blue ...•.•...•.......•...••.....•... 996-1006 Clay, soft, blue .....•...••..............••......1006-1050 Shale, hard, blue . ............•••••....•.........1050-1072 Shale, hard, blue ....••••...• .. ..........•••.....1072-1092 Shale, hard blue ..•...•.•.....•........•..•....1092-1106 Sand rock, hard, blue ... • •.••...............••...1106-1115 Shale, hard, blue •..••.•....•...•.•..•..•·..••...1115-1145 Rock, hard, gray ...•.••.•••...•....•....•.•.....1145-1149 Shale, hard, blue •.••••••••.•..•••..•.••••.•••.•1149-1184 Rock, hard, blue •.•. , •••.••........••....... . ...1184-1191 Shale, soft, blue ......•••...•••••.....••••.••....1191-1212 Clay, soft, light blue .••..••.........•.........•.1212-1300 Rock, hard, blue ••.....•..••·•.•••••..•..•.•....•1300-1306 Shale, soft, blue ...............-•... ~ •..•.•......1306-1356 Shale, hard, blue •.••.••• ~ •••••••••••••.••.•••••.1356-1387 Rock, hard, gray •.•...•.••.•.......•..•••..•••..1387-13·90 Clay, soft, blue ......•..•.••.•.•.•....•••.• . ...1390-1409 Rock, hard, light blue ...••••••••••••••.•••.•••..1409-1446 Gumbo, hard, dark ..............................1446-1746 Rock, soft, white .....•••••......••..•...•..••..1746-1850 Rock, soft, blue •...•.••••.•.••••.••..•••••...•.1850-1910 Rock, hard, white •..••••••...•..•.•.....•...•...1910-1987 Rock, hard, blue ................................1987-2015 Rock, hard, gra.y· ..•.••••..••••..•...•.••••.••...2015-2054 Rock, hard, light blue ..•......••.••...•..•......2054-2080 Rock, hard, gray ..•...•••••.•........•......•·..2080-2140 Rock, soft, dark blue ..••.••.•..........•.. . .....2140-2152 Rock, hard, white .•..••.••••••••••••••.•.•••... 2152-2189 Rock, hard and soft, yellow.; water ••.....•. • ....•..2189-2269 Rock, hard, white; no water ...••••.••••.•.••••••.2269-2304 Geology and Mineral Resources of Bexar County 147 Rock, soft, yellow; water ......... ............. . . 2304-237 4 Rock, soft, yellow, and hard; water ............ .... 2374-2433 Rock, hard, flint; no water . .. . . . . .. .. .. ... . . ... .. 2433-2437 Rock, hard, dark blue; no water .......... ........ 2437-2444 The log of this well is difficult to interpret. The driller states that he was unable to recognize either the Eagleford "lignite" or the Del Rio "mud hole." The water obtained from the well is re­ported to have had a temperature of 117° and to have had a head of about 7 5 feet above the surface. The water which was first ob­tained at the depth of 2189 feet, or at the actual level of about 1700 feet below sea, is derived with little doubt from the Georgetown­Edwards ~imestones. The Del Rio formation is placed provisionally in ,this well at 214 0 feet from the surface or at the actual level of about 1685 feet below sea. This interpretation is permissible from the log. 21. D. Boerman, south side of Bandera Road, 11 miles north­ west of San Antonio. Record from owner. Chiefly limestone and shale (Austin-Eagleford). . . . . . • 0-280 Hard limestone (Buda) ..... , ...... .............. 280-320 Mud hole (Del Rio) . ... .. .. . ... ... ....... . . .. . .. 32 0-385 Limestones (Georgetown) ................... ..... 385-403 24. H. Brendle, 527 Bandera St., about one mile north of west of San Pedro Springs, San Antonio. Log published in 18th Ann. Rpt., U. S. G. S., p. 293. Blue marl and clay described as sea mud in this well from 493­583 feet, is interpreted as the Del Rio formation, which accordingly lies at the level of from 227 to 317 feet above sea. 27. C. C. Clamp, south of the Castroville Road, east of Leon Creek, 6 miles west of San Antonio. Log by Mr. Fred Lewis. Clays, mostly blue in color (Navarro-Taylor) • • • • . . . • . 0-662 White shale (Austin?) . . .. . .. . .•..... . ... . . . .. .. 662-825 White lime rock (Austin) ..... . .... • . . ........... 825-1023 Lignite (Eagleford) .... •..••......••....•• .• •.•• 1023-1054 White limestone (Buda) ..•........ . . . ...........1054-1110 Mud hole (Del Rio) ...• . ....•......•........ . .. . 1110-1162 Limestone ...•••. . •.....•••...•.... . ...... . ....1162-1195 Water sand ...... . ...•. •• ...•..........•.. . . . . 1195-1196 Limestone .••• . .....••.••..•.•••..•.... . ...... . 1196-1220 Crevice, water ..... . .•. . •..• , ..•.• , •. •.........1220-1221 Sandy limestone rock .....•.....•... • .. • •.•...•..1221-1275 Crevice, water ......... . ..• . ...••....•... . .. . ..1275-1277 Limestone .... .. • . .. . .......•.. .. ... . ........ . . 1277-12·92 "Sand" . ... . ... .... .. .... .. .. ... ..... .. . .. .. . . 1292-1308 University of Texas Bulletin Not recorded ....... . ............•..............1308-1396 Limestone rock ....... .. .......................1395-1452 Aside from the surface materials the first 662 feet in this well probably represent the Taylor and a part of the Navar10 forma­tions. The 3 61 feet recorded as white shale and white lime Tl)ck probably represent the Austin formation. The Eagleford lignite is assigned a thickness of 31 feet; the Buda, 56 feet; and the Del Rio, 52 feet. The water-bearing limestones lie at the depth of 1162 feet. As bearing on shuctural conditions it is of interest to note that the Comanchean formations here lie at a lower level than at the Allen well in Kelly Field, about 23h miles farther south, the Allen well being nearer the axis of the San Antonio strµcture, al­ready described. 28. Collins Manufacturing Company, 900 yds. northeast by north of Courthouse, San Antonio. Record from U. S. G. S. 18th Ann. Rpt., p. 293. At this well blue clays were passed through from about 720 to 800 feet which with little doubt represent the Del Rio formation. The Del Rio here lies at about 60 feet below sea level. 30. Collins Gardens, near I. & G. N. Ry. track below Union Stockyards, used for irrigation. Jacob Wolf, driller. Yellow clay and gravel (Pleistocene) . . . . . . . . . . . . . . 0-40 Blue clay, mostly soft and caving (Navarro-Taylor).. .40-525 Limestone (Austin) ............................. 525-855 Lignite (Eagleford) ......................•...... 855-890 Hard limestone (Buda) .......................... 890-930 Mud hole (Del Rio) ............................. 930-1000 Limestone . . ............................... · .. . The blue clays of this well from 40 to 525 feet represent the Taylor and probably a part of the Navarro formations. The lime­stones which may be assigned to the Austin· formation have a thick­ness of 330 feet. The Buda limestone, the first of the Coman­chean formations, fa reported at· 8 9 O feet. In this well good water is reported to have been obtained while in the limestones of the Austin formation, at the depth of 638 feet. 33. Dickenson well, north side of Culebra Road, 8 miles north­west of San Antonio. Alex Lorenz, driller. Elevation of Del Rio, 353 feet. Surface materials, blue clay and limestone (Taylor- Austin) .......... . ..........•.•.....-. . . . . . . . 0-420 Lignite (Eagleford) . . • • . . . . . . . . . • . . • . • • . • • • . . • . . 420-447 Hard rock (Buda) • • • . . . . . . . . . . . • • . • • . . . . . . . . . • 447-497 Mud hole (Del Rio) ..•..••..•.....•...... . ..•. : .. 497-5·67 Limestone rock · (Georgetown-Edwards) ............ 567-602 Geology and Mineral Resources of Bexar County 149 The surface materials at this well include remnants of the grav­els of the Uvalde formation. A part of the clays represeut the lower part of the Taylor formation as indicated by exposures nearby. The limestones under the clays to the depth of 420 feet are of the Austin formation. The Comanchean is entered at 447 feet and the water-bearing Comanchean limestones are reached at 567 feet. 4 2. Geunther l\Iilling Company, 9 0 2 Morales St., east side of I. & G. N. Ry., San Antonio. Yellow clay and gravel (Pleistocene) . . . . . . . . . . . . . . 0-50 Blue clay (Taylor) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50-250 Soft gray rock (Austin) .......... . .... . .. ....... 250-350 White limestone, water (Austin) .. .... . ..... . ..... 350-550 Bluish black shale, lignite (Eagleford) . . ......... ... 550-600 Hard white limestone (Buda) ....... ... ..... . . ... 600-650 Sea mud (Del Rio) .. . ............... . ......... . 650-700 Blue limestone ...... .......... . . ... . . .... ... ... 700-750 "Sand" and black flint strata, water ........... .. ... 750-800 Hard sandstone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 800-850 Flint, gray (and limestone) .. .. .. . .. . ......... . . . 850-875 The log of this well as preserved is evidently a somewhat gen­eralized record. However, it serves to place approximately the top surface of the water-bearing limestones at 700 feet. Some part of the Taylor formation here lies above the Austin and Eagleford, although concealed at the surface by flood-plain deposits. 43. A. E . Goforth, north side Culebra Road, 18 miles northwest of San Antonio. Goforth, driller. Surface materials and limestone rock, the lower part hard and blue in color (Austin formation). . . . . . . . 0-349 Lignite (Eagleford) ... ...... ...... ... ........... 349-384 Hard limestone (Buda) .. . .. ... ... .......... . . ... 384-444 Del Rio clay (mud) ............. . ............... 444-504 Limestone rock (Georgetown-Edwards) .. . ... . ..... 504-564 44. Government well, at Aviation Post, on Austin Road, about 6 miles from San Antonio, Benkendorfer, driller. Soil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.-2 Yellow clay . . ..... . ...... . ...... .. ...... ... ... . 2-55 Blue clay (small vein good water at 190, rose within 100 ft. of surface) ............. .............. . 55-190 Magnesian limestone, soft, light blue ... ..... .. ... . 190-210 Soft shale . . .......... . ......... . ..... ... . ... . . 210-220 Light gray hard limestones ....... .. .......... ... . 220-240 Blue gray very hard limestone .. .... ...... . ...... . 240-260 Hard white limestone ............ .. ............ . 260-280 University of Texas Bulletin Soft white limestone ..••..••..••.. , •••.•..•••.••. 280· 300 Blue and white hard limestone . . . . . . . . . . . • . . . . . . . . 300-320 Not recorded ..........................•....... 320-:J30 Hard white and blue limestones .................. 330-340 ( 8" casing rested ·at 340 ft) Very hard white limestone ....................... 340-353 Lignite, black and soft (Eagleford).. • . • . . • • • . . . . • . 353-380 Gray shaly rock ... .. ........................... 380-400 White hard limestone . . . . . . . . . . . . . . . . . . . . . . . . . . . 400-418 Del Rio "mud," soft, blue-gray....•............... 418-494 ( 6" casing rested at 494 ft) Limestone, slightly yellow, hard .................. 494-557 Limestone, light in color ......................... 557-575 Porous limestone ............................... 575-580 Hard brown limestone . . . . . . . . . . . . . . . . . . . . . . . . . . 580-590 Soft limestone ............ , ..... . .....•........ 590-625 Hard brown limestones.•.•...•...•...•....••.•.•• 625-655 Flinty limestone ... . ............................ 655-657 Soft limestone .........................•... ....· 657-671 White hard limestone . . . . . . . . . . . . . . . . . . . . . . . . . . • 671-680 Soft brown limestone ......................·. . . . . . 680-690' Hard limestone .. . .... . ... . ....... . . . ... , ....... 690-748 Black flint .. ................................... 748-750 Hard yellow limestone ........................... 750-795 Very hard limestone ........................... . . 795-835 Light brown soft sandstone . . . . . . . . . . . . . . . . . . . . . . . 835-855 Light brown limestone . . . . . . . . . . . . . . . . . . . . . . . . . . . 855-87 4 The formation penetrated in this well to the depth of 353 feet is chiefly the Austin including possibly some of the Taylor at the surface. The combined thickness of the Eagleford "lignite" and Buda "shaly rock and white limestone" is recorded as 65 feet. This is unusually t.hin for these formations unless a part of the Eagle­ford has been included with the limestones referred to the Austin. All wells between the east city limits of San Antonio and Salado Creek record a reduced thickness of the Eagleford, Buda, and Del Rio formations. 45. Government well, Fort Sam Houston, near west limits of Government Reservation between Pine Street and River Avenue, San Antonio. Judson, driller; 1903; depth 729 ft.; casing ·10-in. to 630 ft. Elevation, 689. Non-flowing, although stood in well when completed within a: few feet of the surface. Elevation Del Rio, 6·9. Blue loam and flint boulders . . . . . . . . . . . . . . . . . . . . . . 0-3 Yellow clay ................................... . 3-41 Blue clay .... . ............................... . 41-258 Magneslan limestone. Small streak of good water at Geology and Mineral Resources of Bexar County Fil 350 ft. . ....... . ............ . ............... . 258-354 Gray limestone, sulphur water ......••.. .. ........ 354-392 Gray limestone, hard ... . . . .. . •...... . ........... 392-429 Yellow limestone ..... .. .................•...... 429-468 Gray limestone ....... . ........................ . 468-535 "Lignite" (Del Rio) ...........•. ..•. ............ 535-566 Gray limestone (Buda) .......•••.•••••••.•••••••• 566-62 0 Blue clay with shells (Del Rio) .••••..••.•......... 620-673 Blue limestone ......... .. . . ................... . 67 3-688 Hard yellow limestone ..............•............ 688-706 Calcareous limestone .. .. ............. . .. .. ... . . . 706-708 Struck water at 7 0 5 ft. Open cavity . . ................ . ..... . ........... 708-713 Hard limestone with fissures filled with clay . . . . . . . . . 713-7 2 9 This well may be compared with the new city well drilled at the north city limits in 1918. Although only about 1 mile farther north, the Del Rio at the city well is found at the level 4 9 7, or more than 400 feet higher than in this well, the two wells being separated by a large fault. 46. F. Grote, south side of Bulverde Road, 61h miles from San Antonio. Alex Lorenz, driller. Soft "adobe" lime . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0-17 Hard limestone (Austin) . . . . . . . . . . . . . . . . . . . . . • . . . 17-187 Lignite (Eagleford) ..•••...•.••.•••..••......... 187-222 Hard limestone (Buda) ..............•...... .. .. 222-272 Clay (Del Rio) .... . ............................ 272-332 Hard limestones (Georgetown) .....•..•.....•.... 332-339 This well starts in the Austin formation surface exposures of which are seen nearby. The Comanchean formatians are entered at the depth of 2 2 2 feet. The water-bearing limestones were reached at 332 feet and were drilled into only 7 feet. The well is located on the structurally high area elsewhere described as the San Antonio structure. 49. Jud Harrison, west side Blanco Road south of Coker cross road, 81h miles north San Antonio. Alex Lorenz, driller. Not recorded (Austin) . . . • . . . . . . . . . . . . . . . . . . . . . . 0-185 Lignite (Eagleford) .........•.••..........••.... 185-190 Hard limestone (Buda) .......................... l 90-245 Clay (Del Rio) ........ . ..•..•.................. 245-300 Limestone (Georgetown) ...................... .. 30tl-328 56. Herff well, formerly the Werner property, north of Castro­ville Road, between Stephenson Road and West 34th St. Benken­dorfer, driller. Record from driller's notebook. Del Rio mud University of Texas Bulletin recorded at from 1000 to 1060 feet, the water-bearing Coman­ chean limestones thus lying at the level 350 below sea. Surface clay and gravel (Pleistocene) . . . . . . . . . . . . . . 0-31 Yellow clay (Ml.varro) . . . . . . . . . . . . . . . . . . . . . . . . . . 31-81 Blue clay (Navarro-Taylor) .·. . . . . . . . . . . . . . . . . . . . . . 81-621 Magnesian limestone (Austin) .................... 621-781 Blue limestone (Austin) ......................... 781-811 White limestone (Austin) ........................ 811-961 Lignite (Eagleford) ............................. 951-969 Gray limestone (Buda) .......................... 969-1060 Clay (Del Rio) . .. .............. . .............. . 1050-1110 Brown limestone ............. . .................1110-1140 Porous limestone, water rock .............. .. .....1140-1286 The surface clay and gravel at this locality includes that of the flood-plain deposits. Aside from these surface materials the Upper Cretaceous is here recorded as having a thickness of over 900 feet, the Comanchean ·limestones (Buda formation) having been reached at 969 feet. Judging from the thickness of the Upper Cretaceous there are probably present here the Eagleford, Austin, Taylor, an.d lower part of the Navarro formations. 57. Hill and Roby, east side Pleasanton Road, 714 miles south of San Antonio. Jacob Wolff, driller. J910. Depth, 1890. Elevation about 625. Flowing warm sulphur water. In this well the Del Rio clay is said to have been passed through at .from 16·95 to 1750 feet, or at the actual level of from 1060 to 1125 below sea, The formation thus lies more than 300 feet·lqwer th&n its estimated level in the Alta Vista oil field, a few miles farther southwest, and but little less than 200 feet lower than in the Ripps well a short distance southeast. 59. R. H. Hofheintz on Pearsall (Frio) Road between public road and railway, just north of Kelly Field, four miles from San Antonio. Benkendorfer, driller. In this well the Comanchean formations were entered at 950 feet. The overlying Cretaceous includes probably the Eagleford, Austin, Taylor and the lower part of the Navarro formations, as well as the surface flood-plain deposits. The Del Rio formation was entered at 1000 feet, or at the level of 315 feet below sea. The water-bearing Comanchean limestones lie at the depth of 1054 feet and were drilled into to the total depth of 1453 feet. A lo~ of this well is given in Bull. 298, U. S. G. S., p. 268. 60. Holtz well, on left bank of Leon Creek below the Somerset Road crossing, nine miles southwest of San Antonio. This well was drilled by rotary by Holtz to a depth of 1200 feet where hard rock Geology and Mineral Resources of Bexar County 153 was reached and where the 6" casing was rested. From this depth the well was drilled with cable tools by Benkendorfer. Temperature of water said to be 106.5 F. 63. Hot Wells Hotel, on San Juan Boulevard, 114 miles south of the south city limits of San Antonio, east side of San Antonio river. Robert Newton, driller. Soil 0-5 Yellow clay .... ..... .... ... ........ . ... .. . . ... . 5-15 Black sand ................... . .............. ..· 15-20 Sand and gravel, water .. . ..... . ..... .. ......... . 20-30 Yellow clay ................................... . 30-52 Blue shale . . ............ .... .. . ......... . ..... . 52-90 Streaks of lignite ...... ...... . ........ . ........ . 90-95 Gumbo and blue clay.••••••• , , ••••••• , • , • , ••••••• 95-125 Sandy shale •••.•••.•••.•••••••••••••••••••••••• 125-175 Gumbo .... .......... ... ....... ......... . .. .. . . 175-323 Sand rock .................................... . 323-325 Gumbo .................................. . .... . 325-3;{7 Sand rock .................................... . 337-340 Gum·bo .... . .... . . . .......... .... · ·. · · .. · · ... ·. 340-351 Rock ..........•..••..•..........•.•...•.•••••• 351-353 Sar1dy shale ......•...•.•••••••••••••••••...•... 353-412 Gumbo ...... . .... ...... .. . .... ...... .... .. ... . 412-506 Sandy shale ..... .. . ... ..... ... . .. ......... .. .. . 506-577 Sand rock, oil show ............... .. ..... . ..... . 577-587 Gumbo ....................................... . 587-597 Sandy shale ................................... . 597-710 Hard gumbo .................................. . 710-990 Lime rock, casing 8" set....................•..... 990-1003 Lime rock ... .. .. . . .. ... ....... ... ........ .. .. 1003-1445? Gumbo and hard shale ...........................1445-1454 Lime rock .....................................1454-17 40 Hard shale ... ............. ... ....... . ... . . .. .. 1740-1748 Hard lime rock, pink .... . ... ...... ... .. .........1748-1865 Sand lime, some water ... ... ...... . ... ....... . . .. 1865-1875 Porous rock, sulphur water .......................1875-1878 This well having been drilled by rotary does not afford as defi­nite information as the wells drilled by cable tools. The log is given as made out by the driller. While the interpretation of the log is in doubt, it is probable that aside from surface materials, the first 990 feet represents chiefly Navarro and Taylor formations; while from 990 to about 1445 represents the limestones of the Austin, Eagleford, and Buda formations. On this interpretation the Del Rio lies here at about 1445 feet from the surface or about 870 feet below sea level. 154 University of Texas Bulletin. 67. Kearney Oil and Pipe Line Company, No. 3, west side of Palo Alto Road about one mile south of Leon Creek crossing. Yellow clay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • • 0-42 Blue clay . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . 42-125 Black sand, gas show .......•......... .. ....... . . 125-161 Blue clay ..... ...... .. . ......... .. .. .• . .. ...... 161-226 Sand rock . . ...•..•...... • ........•............ 226-234 Gumbo .. . ........•....... . ..•.•..•..•......... 234-261 Sand rock ........................•............ 261-262 Gumbo . . . . . • . . . . . . . . • . . • . . . • . . . • • . . . . . . . . • • . . . 262-268 Soft rock ....•......................••......... 268-269 Gumbo . ... ...............•.......•............ 269-27:1 Soft rock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . 273-27 5 Gumbo and soft rock .......••..•..••.•.......... 275-392 Shale ........................•................ 3-92-433 Hard rock .................•...........•.....•. 433-449 Gumbo ...........................•.......•..•• 449-4!16 Gumbo and shale, oil show ......•........ ; ........ 486-527 Gumbo . ... ..... . .........•....•••.•...•.•.••.. 527-569 Gumbo and shale, oil show . . . . .. . . . . . . . . . . . . . . . . . . . 569-621 Soft rock, oil show . .. . . ...........•...•........ 621-636 Gumbo ...... . ........ . .....• . ......•....... • . . 636-703 Shale ......................................... 703-724 Gumbo ................ .•......·.................. 724-745 Not recorded .....•.......•..................•.. 745-837 Rock (limestone) .. ..... . ............. . .•. • ..... 837-869 Gumbo ......•..........................•...... 869-872 Soft rock .....................•................ 872-886 .Gumbo .... ......•..............•..•••. •... ., . . 886.. 890 Soft rock ........................... : ...• • ••... 890-892 Gumbo . .. ....... . ......•.........•..........•. 892-957 Hard rock (limestone) ...............•....•..... 957-1063 Yellow rock (limestone) .......•...••........•.•.1063-1151 Sand, heavy oil, about 2 bbls. per day......•........1151-1161 White limestone and water ...............•...•. . . 1161-1211 Yellow limestone and water (sulphur) •.............1211-1221 W:hite limestone ... ....... ... ... ...............1221-1321 Lignite, kind of mud (Eagleford) •••••.•.••••.•..•.1321-1357 Black limestone (Buda) ......••...•.•.•••••••••••1357-1451 Mud hole, sea shells (Del Rio) .............. . .....1451-1491 Hard black limestone.•. .. •..•............ . ......1491-15·91 Warm sulphur water..•........•.•.••.•...•.. ·....1591-1861 White rock, salty water..•.. ...•..•..•..•..•..•..1861-1881 Cold water, brackish...............•..••.........1881-1991 Not recorded .............••..•..•..•..•........1991-230:.5 Thts well, log of which has been given by Mr. Kearney, atrords a very important and reliable record of the depth of the formations Geology and Mineral Resources of Bexar County 155 at this locality. The well is located within the belt of Tertiary exposures, provisionally mapped as Midway. The interval from the surface to 957 is assigned to the Midway, Navarro and Taylor for­mations. The Austin formation apparently is represented by the interval from 957 to 1321 .feet, 364 feet, consisting chiefly of lime­stones, with some slight production of heavy oil at 1151 feet. The record of the Eagleford "lignite", Buda limestone, and Del Rio clay is unmistakable. To the Eagleford is assigned a thickness of 36 feet, to the Buda, 94 feet; aud to the Del Rio, 40 feet. The Georgetown-Edwards limestones were entered at 1491 feet. \Varm sulphur water was obtained in these limestones. The drill hole was continued below the top of these limesones 964 feet, probably terminating in the Glenrose formation. Mr. Kearney believes that the water obtained below 1881 feet was neither so warm nor so salty as that from a somewhat higher level. Mr. Jacob Wolff believes that the cool non-sulphur water lies below 1900 feet from the surface. The interval between the oil sands in the A1~slin and the top of the Del Rio formation in this well is about 31iO feet. The whole thickness of the upper .Cretaceous as indicaed by this well is about, or a little mo"re than, 1200 feet. The stratigraphic in­terval from the greensand horizon near the top of the Navarro to the top of the Del Rio is 132 6 feet. The actual level of the Del Rio at this locality is 8 41 feet below sea level. 73. Well in Lakeview Addition, near 24th Street, west part of San Antonio, north of Elmendorf Lake. Black soil . .........•.......................... 0-4 Yellow clay ............... .. ..................• 4-31 Soft blue clay...... .......................... . . 31-43 Not recorded 43-187 Hard streaks at.......•.•..•..•.. ....••.•........ 187 Not recorded .......••••••••.•.••••••.•.••...... 187-190 Sand rock, six inches at ..........•..•......... . .. 190 Not recorded ..•..•••.•.•••••••••.••••••......• 190-206 Hard lime rock...••••••••••••••••••••••••••.•.. 206-281 Black lignite (Eagleford) ....•.••...••.•..••..•••• 283-291 Streaks black lignite at......................... . 349 Not fully recorded. . . . . . . . . . . . . . • . . . . . . . . . ..... . 291-441 Blue mud (Del Rio) .••••...•.••••••••••••••••••• 441-494 Soft dark sandrock .••..••.•.••.•...•••.•.•••... . 494-522 "Granite" . . • • • • • • . . • • • • . • • . • . • . • • . . . . • . . . . • • . . 5 2 2-5 8 6 Sand rock with water ............................ 586-591 This log is very unusual and is difficult to interpret. If the blue clay at 441 feet represents the Del Rio, the formation lies here at about the actual level of 239 feet above the sea. University of Texas Bulletin 74. W. F. Legler, on north side Castroville Road, 6 miles west of San Antonio. Alex Lorenz, driller. Soil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • • • • . . . . . . . . . ~ 6 Clay and gravel (Pleistocene). . • . . . . . . . . . • . . . . . . . . 5-lll Yellow clay (Navarro) ............. .-. . . . . . . . . . . . . . 18-52 Blue clay (Navarro-Taylor). . . . . . . . . . . . . . . . . . . . . . . 52-670 White shale (Austin) . ..... .. ....... .. ........ . .. 670-910 · Limestone (Austin) ....... . ..................... 910-1080 Lignite (Eagleford) •.•••••••.•••••••.••••••••.••1080-1108 Hard rock (Buda) .......... . ....•....•....... . . 1108-1167 Clay (Del Rio) .. ........ . .. . .... . ....•....• . . .. 1167-1220 Limestones, water bearing at successive horizons. .....1220-1665 The top of the Comanchean formation in this well is reached at 1108 feet below the surface, the upper Cretaceous formations present being probaly the Eagleford, 2 8 feet; Austin, 310 feet; Taylor and lower part of the Navarro, 618 feet; and the Pleistocene flood-plain deposits amounting to about 18 feet. 75. J. Locke, west side of Blanco Road, 5 miles north of San Antonio. Alex Lorenz, driller. Yellow calcareous marl (Austin) . .. ............. . . 0-50 Blue limestone rock (Austin) . ........... .. .. . .. . . 50-250 Lignite (Eagleford) ...••........ . ••••.....•..... 250-265 Hard white rock (Buda) .......... .............. . 265-310 Sea mud (Del Rio) ............. .............. .. . 310-370 Limestone (Georgetown) 370-385 77. Alex Lorenz, north side Bulverde Road, about 6 miles north of San Antonio. "Adobe" 0-25 Blue "mud" rock (Austin) .. ............ ........ . 25-150 White limestone rock (Austin) .... . . .. .... . .... ...· 150-270 Lignite (Eagleford) •••••••••••••••••••••••••••.• 270-295 Hard limestone (Buda) ...... . ....... . .... .. ... . . 295-345 Clay (Del Rio) ..................... .... .. ..... . 345-400 Limestone rock (Georgetown) . . .......... . .. . ... . 400-420 80. B. F. Masterson; about.1 mile north of the Castroville Road, 18 miles west of San Antonio. Test well for oil. Record from Geo. B. Mechem Co. In this well, according to a summary of the log supplied by the owners, the Del Rio formation is believed to have been entered a.t the depth of 734 feet from the surface, and to be 83 feet thick. The GeorgPto·1rn-Edv.ards limestones were reached at 817 feet, and the drill hole was continued to 1620 feet probably terminating in the Glenrose formation. Geology and Mineral Resources of Bexar County 157 81. Chas. Matyear, near 24th Street, in Lakeview .Addition, San .Antonio. Alex. Lorenz. driller. Elevation, 67 8. Elevation of Del Rio, 186. Black earth . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . 0-4 Yellow clay . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . • 4-31 Soft blue clay . • . . . . • . . . . . . . . . • . . . . . . • . . . . . . . . . . 31-43 Not recorded . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43-187 Hard streaks ............. . ... . ..... .. .......•.. 187 Black sand rock ........... . .......... . ......... 190 Hard lime rock .......... . .......• .. ............ 206-281 Like black lignite (Eagleford) •.•••......•.•••.••.. 283-291 Streak black lignite. • • • • • • • . . • • • • . • • • • • • • . . • • • • • • 3 4 9 Blue mud (Del Rio) ••.••.........•.. . ..••....... 441-494 Soft dark sandrock . .•....... . . . ...........•..... 519-522 ''Granrte'' 584-586 Sand rock, water . ................ . ..... . ........ 591 82. Medina Fuller's Earth Company, about one mile north of Castroville Road, and west of Cagnon Cross Road, 16 miles west of San Antonio. Alex. Lorenz, driller. From the stratigraphic inter­val from the surface to the Del Rio formation it appears that this well starts in the Taylor formation. Blue marl ......•...•...................... ; . . . 0-400 White soft rock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 400-600 Eagleford ... . ...... . ........................... 600-635 Buda .... .. ...........•.... . .... .. ...... . ..... 635-685 Del Rio . .. ......... . ...................... . ... 685-750 Georgetown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • • 7 5 0-7 7 8 .Actual level, Del Rio............................. 100+ 83. Medina Oil Company, south of Leon .Creek, west of Apple­ white Road. Jacob Wolff, driller. 4-inch casing set at 1530 feet; first flow of sulphur water at 1540 feet; second flow, 1800 feet; depth of well 1833 feet. Yellow clay ......... ....... ... ...... ......... . . 1-15 Gravel ..................... . ................ · · 15-25 Black sand ...... . .................•...... . .... 25-50 Blue clay ..............•......•....... .•....... 50-100 Blue rock .. . •............••...............•.•. 100-104 Blue clay .............•...... . .. ... ..•......... 104-124 Blue rock, showing oil . . . ....•.................. 124-1211 Blue clay ... . . . .................. · · •. · · · · · · · · · · 1211-145 Blue rock ..........•.....•.................... 145-153 Light blue clay ...............•............. . ... 153-165 Blue rock . . .. . ....•..•••....••................ 165-169 Blue clay .....•..............••........•...•... 1611-176 Blue rock ..........••....•....•............... 176-186 University of Texas Bulletin Blue clay .... . ..........•.....•..•.·•.•...••.... 186-200 Blue rock ..... . ..........•...•.......•••.....•• 200-206 Blue clay ....................•..•............. 206-217 Gray rock ....... . ..............•.......••..••. 217-255 Clay and uan.d, gas •••••.••.••••••••••••••••••••• 255-296 Gray rocl!: . • •.....•.••...-•..•••...•...•••.••..•.• 296-302 Blue clay •••••.•••••..•..•...•.•..•.•••...••.•. 302-348 Gray rock .... . .•.....•........•.........••.... 348-355 Light blue cla,y ........· .......•..............•... 355-408 Blue rock . ............... . .... ·. · •.. · .. · · · · · · · 408-416 Blue gumbo .....•..............•...•.••.....•.• 416-436 Dark blue clay .•••.....•..•...•.........•...... 436-496 Dark gray rock ............•....•.•....••..•••••. 496-500 Hard blue clay ....•....•............•.......... 500-548 Dark gray rock .......................• . .•.•... . 548-552 Dark gray shale, gas and oil .•.•...•.. . .•......... 552-564 Dark gray rock •...........•..•...·..•........... 564-567 Dark clay and sand, gas and oil .•.•••.••........••. 567-630 Gray rock ........••.....•..•...........•.•..•.. 630-633 Dark hard clay .......•••....•...•..•... ........• 633-665 Hard gray rock ....••.....•..•.......•........•. 665-671 Hard blue clay ....•....... . .....•............•. 671-728 Gray rock ......•••........•...•...•.......••.. 728-736 Blue clay ...•....•.....•.••..•·..•••••.••.•.•.•. 736-783 Black rock ......................••...•....••.•. 783-7·!11 Dark clay ............. , ....................... 791-806 Dark rock .•.•...•..•••......•.••••.......••... 806-836 Gray shale with oll • • • • • • • • • • • • • • • • • •.• • • • • . • • • • • • 836-858 Hard dark rock ....•.........•..•...•.....•.... 858-912 Hard light blue rock ........•.......•.•.•.......• 912-922 Hard dark gray rock •...•....••..•..•.•...•..•.• 922-!143 Hard white rock •...•••••••..•..•.•.......•.••.• 943-950 Hard light blue rock •••••.•...•••••••.•.••...•••. 950-953 Yellow shale with oil •••.•••.•...•.•..••.•••..•.. 963-957 White rock •••...••••••.•.••.•.•••••••.....••.• 957-960 Light blue rock ...•••..••.•...•.•.•••••.•..•..•. 960-964 Yellow shale with oil .••..•..•••..••••..••..••..• 964-982 Light blue rock ...•••...••••.•.•••..•..•.•.•..• 982-986 White soft rock .•..•.•.•••..•...•.•••..•....... 986-990 Light blue hard rock • • • . • • • • • • • • • • • • • • . • • • • • • • • • 990-994 Yellow shale with oil ••....•••.•.•.•..•••.•••.••. 994-1012 White rock ••...•.•.••..•.•••••••..•••••.•...••1012-1014 Blue rock ..•.••...•.•.•......••.•••••••..••.••1014-1015 In this well, the Del Rio formation is reported at 1460 feet from the surface, or at about 920 feet below sea level. At 26 feet there is reported a black sand which very possiblY .is the glauconitic Geology and Mineral Resources of Bexar County 159 sand horizon of the Navarro formation. If so, the thickness of the Upper Cretaceous as recorded in this well is 142 5 feet, wliich is somewllat greater than farther northwest as indicated by the Kear­ney, Vogt, and Ridder wells. 93. A. J. Ridder, east side of Medina River, 13 miles southwest of San Antonio, north of Pearsall Road. Several wells on this property. L. N. Knight, driller. In all of these wells the glau­conitic greensand is noted, and the wells are of interest as indi­cating a south or southeast dip. They are as follows: Deep well, north side Southern Pacific track; depth, 2911 feet; elevation 628; flowing artesian water. In this well no water was found until below 1502 feet, the forma­tions being entirely dry to that depth. Successive water horizons between 1557 and 1980 feet were found. A glauconitic greensand horizon was recognized at 165 feet from the surface, the greensand being 50 or 60 feet thick. The Del Rio formation was recognized at 1444 feet and continued to 1497 feet. The limestones below the Del Rio were drilled into 1413 feet. From this record it appears probable that the well terminated either near the base of the Glen­rose or in the Travis Peak formation. In this connection it is of interest to note that the driller reports having drilled into fossil wood not petrified, but more or less lignitized, near the bottom of this well. This deep well affords a record of praCtically the full thickness of the Upper Cretaceous. While the Buda is not recorded, its uni­form thickness of 65 or 70 feet overlying the Del Rio makes it pos­sible to place the top of the Comanchean at about 1374 feet from the surface. The greensands reached at 165 feet are with little doubt those of the Navarro formation as exposed on Leon Creek. The Upper Cretaceous is therefore 1200 feet thick at this well, possibly a little more. This agrees closely with the thickness ot these formations as determined from the Kearney well, about 6 miles farther southeast, where the Upper Cretaceous formations appear to have a thickness of about 1232 feet. Another measurement obtained from this well and from the Kear­ney well, used in estimating the place of the Del Rio in some wells, is the stratigraphic interval between the glauconitic greensand aud the top of the Del Rio formation. Jn this well this interval is 1279 feet; in the Kearney well, the same interval was found to be 1326 feet, or 47 feet greater. Ridder well, near west line of property. Elevation 617. Green­sand at 200 feet from surface, or at level of 417 feet above sea. Ridder well, on north side of Pearsall Road, about % mile from Medina River. Elevation 617. Greensand at 235 feet from the sur­face, or at level 382 feet above sea. Ridder well, on east side of Medina River. Elevation 595. Some University of Texas Bulletin water obtained at 1056 feet; additional water at 1410 feet. Green­ sand at 285 feet from the surface, or at level 310 feet above sea. The dip in the formations from the deep well north of the railway to this well on the river, a distance of about one mile, according to these records is 150 feet. That this dip continues to the south is indicated b,y the Vogt well, subsequently recorded. 97. St. Louis College, between Culebra and Bandera roads, about 5.4 miles west of San Antonio. Elevation, 760. Flint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0-3 Adobe ...................................... . . 3-5 Yellow clay ............................ · ... ·. · · · 5-65 Blue clay ....................•................. 65-215 Magnesian lime rock ................. . ..... · .. · · 215-288 Hard blue lime ...............................•. 288-3!!2 Hard yellow rock ..............................• 392-402 Hard gray rock .... .. .......................... . 402-465 Lignite (Eagleford) ...............•............. 455-485 ·Limestone (Buda) .....................•......... 485· 542 Blu·e clay (Del Rio) .........••................•. 542-590 Dark blue limestone ............................ . 590-600 Yellow limestone ............................... 600-636 Crystallized limestone . . . . . . . . . . . . . . . . . . . . . . . . . . . 636-680 Water rock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 680-702 The Del Rio in this well lies at 547 feet from the surface. An­ other well on this property located 375 feet west of the one re­ported reached the Del Rio at 590 feet or 43 feet lower than in the first well. Aside from this difference in level, the formations are much the same in the two wells. By reference to the struc­tural map it will be seen that these wells are located but a short distance north of the large fault which passes between the wells and the Castroville Road. 98. Salado Water Supply Company, %. mile south of Austin Road, about 5 miles northeast of San Antonio, on Salado Creek. Jacob Wolff, driller. 6000 gallons water per minute. Surface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0-8 Dark blue clay . . . . . • . . . . . . . . . . . • • . . . . . . . . . . . . . .. 8-108 Light blue clay ................................. 108-215 White rock, soft ...........• , , ................. 215-330 Yellow rock, sulphur water ....................... 330-350 White chalk, hard ........................ . ..... 350-445 Lignite (Eagleford) •.•••.. , •.•..•••...•••.. , • • . . 445-470 White rock, hard ........... , ................... 470-510 White pearl rock .........•............... , .•... 510-5l!O Blue hard rock ...........•.... , . . . . . . . . . . . . . . . . 520-5fl0 Geology and 11'lineral Resources ol Bexar County 161 Sand hole .................................... . 540-58f> White rock, hard ......... . .................... . 585-610 Red sand rock, gas flow .. . ..................... . 610-617 Hard white rock ............................... . 617-642 Brown flint ................................... . 642-647 Yellow water rock, white streaks ......... . ....... . 647-702 99. San Antonio and Aransas Pass Railway, at "roundhouse" on railway near the intersection of Proban and Simpson streets, west of the San Antonio River, near intersection of S. P. Ry. and S. A. & A. P. Ry. south of San Antonio. Allen Burman, driller. Sulphur water was obtained from the Austin at 620 feet, from the surface; good water was obtained at 1065 and at 1090 feet. The water is reported to rise 50 feet above the ground level. The Del Rio clay in this well lies at 270 feet below sea level. Casing, 71h" to 550 feet. The Del Rio is cased off by 7 0 feet of 61h" casing. Soil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0-6 Soft white clay ............... ............... .. . 6-22 Sticky yellow clay . . .... . ....... ..... . . . ..... .. . . 22-30 Hard blue clay ..... . .. . .. ......... ... . . .. . .... . 30-100 Soft blue clay ........ .... .. , ..... . .... .. . ..... . 100-250 Hard gray clay ................................. . 250-300 Soft white soapstone ........................... . 300-350 Hard blue clay .. .. ...... . . . ........... ... . .... . 350-400 Soft white clay .... ... . ........................ . 400-'iOO Hard whit~ rock ..................... . ......... . 500-550 Hard white rock ..... ........... ........ ..... · . 550-600 Soft gray rock, sulphur water at 6201 . • •••••. • 600-700 Hard gray rock ...... ... .... . . .. .... . . .. .. . . . .. . 700-750 Hard white rock ......... ................ ..... . . 750-850 Hard brown rock .. .... ..... .. ................. . 850-900 Hard blue sea mud (Del Rio) ...••.••••.•••••••••• 900-9511 Hard white limPstone ........... . .... . . ........ . 950-1103 101. San Antonio City Water Supply, about 400 yards west of Concepcion :\Iission, south San Antonio. A second well drilled about 200 feet north of this one records only about 7 feet of Del Rio, entered at 1~70 feet. The reduced thickness of the Del Rio to­gether with the abrupt dip probably indicates faulting at this locality with the downthrow to the south. Surface elevation of this well about 605 feet. ~Vater in completed well rises 72 feet above floor of derric-k, or to elevation of 680 feet. 10 Surface materials ........ .. . ........ . . .. ..... . . . ')-54 Blm:· clay ...... .. .. ..... .... .. ............. ... . 5 4-780 ":\lagnesian" limestone ...... ...... . . .... ..... . . . 780-900 11 pipe rested at ........ .. . .......... .. . .. ... . 800 11-Bex. University of Texas Bulletin Gray limestone . ... . ........ .. ......... ... .. . ... 906-1197 Water at 1130. Lignite (Eagleford) ..••••.••••••••••••••••••••••1197-1223 Limestone with crevices and water flowing at surface 3000 gals. per min. ........... . ... . .. . . 1223-1280 Mud (Del Rio) . .. . . .......... .. . . .... . .........1287-1328 Limestone with crevices and water ...... . .........1323-1440 102. San Antonio Cit.y Water Supply, Market Street. Surface elevation about 660 feet. Actual level top of Del Rio, 725. Surface materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0-35 Blue clay ................. ........... · · .. · · · .. . 35-220 Hard rock ........ ............................ . 220-375 "Magnesian" rock ... . . . ... .. .. . .. . ..... . ... ... . 375-500 Sulphur water at ... ... ... .. ..... . ........ . .. . . . 505 Lignite (Eagleford) . • ........•...•.•••.....•.••. 600 Buda not given "Mud" (Del Rio) . .......... .. .......... . . .. ... . 725-775 Limestone rock . .. .... . .... ..... ... .... .. . . .... . 775-887 Water mostly at .. . ..... ... . ............. . . . ... . 860-885 103. San Antonio City Well, north city limits on San Antonio River. Benkendorfer, driller. This well starts in the Austin al­though as the record indicates, within about 100 feet of the base of this formation. The Eagleford is thin, apparently only about 15 feet thick. By reference to the map it will be seen that this well is located very close to a large fault. Mud and soil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0-12 Rock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-21 Yellow rock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21-65 Blue rock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65-73 Yellow rock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73-82 Brown rock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82-87 Blue rock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87-96 Yellow rock. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96-101 Brown lignite (Eagleford) .•. . .••••••••. • •.••••.•• 101-116 Yellow hard rock ....... .... .. . ... . . ..... .. .... . 116-144 White hard rock ............... ...... ........... 144-149 Gray hard rock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149-173 Blue mud (Del Rio) ..••••••..••.•.••••....••.•.• 173-234 Yellow water rock, very hard; some flint to bottom of well . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234-702 Principal water supply at 650-670 feet; water rises just to top of pipe. Does not flow over. 104. San Antonio Portland Cement 'Company, on I. & G. N. Ry., 5 Geology and Mineral Resources of Bexar County 163 miles northeast of San Antonio. Log from memory; depth of form a lions approximate: Yellow clay .. .. . . . .. . ........... . ............. . 0-60 Blue hard rock ............................ . ... . 60-250 White and yellow limestones .............. . ..... . 250-400 Honey-combed hard limestones .......... . .. . .. . . . 400-450 Lignite (Eagleford) .........•................... 450-462 Hard yellow limestone ...... . .......... . .. . . .. . . . 462-572 Bl~. ck rock .. . ..... . .. . ... .. ... .. . .... ..... .. .. . 572-587 Sea mud (Del Rio) .. .............. .. .. . . .. .... . . 587-657 Hard limestones . . .. ........... . ......... . • . .. . . 657-667 This record given to the writer by the driller from memory can be used only as an approximate statement of depths to the forma­tions. . Another record of a well at this locality, from notes con­tributed by Mr. Deussen, differs somewhat, placing the Del Rio probably nearer the surface. The uppermost 60 feet in this well is probably the Taylor formation. The next 3 9 0 feet is to be re­ferred to the Austin formation. The materials recorded as lignite, hard yellow limestone, and as black rock presumably include the Eagleford and Buda formations, giving them a combined thick­ness of 122 feet. The Del Rio, "Sea mud," is recorded as having its usual thickness of 7 0 feet. The well is here recorded as entering the Georgetown at 657 feet, this formation having been drilled into only about 10 feet. 107. George Sauer, Bulverde Road, near Haags' store, 6 % miles from San Antonio. Alex Lorenz, driller. Limestone (Austin) .. . ........ . ................ . 0-170 Shales (Eagleford) . ... . ... . ....... . .... . ...... . . 170-210 Limestone (Buda) ........ .... ....... ...... .... . 210-260 Clay (Del Rio) ......... . ... . ..... . ... . ....... . 260-330 Limestones (Georgetown) ..... . . .. .. . . . . ... ... .. . 330-370 108. Henry Shumeier, 1 mile south of Wetmore, west side Bulverde Road. Lorenz, driller. Elevation 760 ; non-flowing ar­tesian water. Adobe and hard rock (Austin) .. ........ ....... ... . 0-250 Lignite (Eagleford) ............ . . .. .. . . . . ... .. . . 250-275 Hard rock (Buda) ........................~ . ... . 275-325 Mud (Del Rio) . . ..................... . . · · · · · · · · 325-375 Limestone rock . . ....... . . ....... ... · ... · · ... · · · 375-420 109. Shattuck well, on 19th• Street, about 1 mile south of El­mendorf Lake, and near the west city limits of San Antonio. L. N. Knight, driller. Chiefly yellow and blue clay .... ...... .. .... . ... . . 0-335 Limestone ...... ....... ... ....... .... .... ..... . 335-703 University of Texas Bulletin Eagleford .. . ............ .. ..... . .•............. 703-735 Buda ..... . ............ . ......... . ........... . 735-798 Del Rio ................ .. .......... .. ......... 798-856 Limestones . . ....... ............ •............... 856 111. Southern Ice Company, Durango and Frio streets, east of I. & G. N. Ry., and south of Commerce Street, San Antonio. Soft pebbles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0-5 Hard pebbies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-'8 Yellow clay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-48 Brown clay ................. . ..... . .... . ...... . 48-160 Brown clay, light ..... . ........................ . 160-260 Magnesian rock ................................ . 260-385 Lime rock ....... . ..................... . ...... . 385-520 Sulphur water at .... . ... . ..... . ..... . . ... .. . .. . 428 \Vhite limestone .......... . ................... . . 557 Not recorded ....... . ... . ... . .... . . . ..... . ..... . 557-566 White clay ...... .. ...... . ..... . ...... . ...... . . 566 Not recorded .... ... .... . ........... . ..... . .... . 566-!'i85 "Coal" (Eagleford) .... •......... . .............. 585-600? "White lime (Buda) ................ , . . . . . . . . . . . 600-650. "Mud" (Del Rio) . . .. .............. . .. . ......... 650-711 Limestone (Georgetown-Edwards) ..... .. .. .. .. . ... 711-911 113. Southwest Land Corporation, about 300 yards south of Commerce Street and 1 mile west of Lady of the Lake College, San Antonio. T. H. Little, driller. Sulphur water at 410 feet. Elevation, 708. Good water at 715 and 850 feet. Gravel and yellow cla,y (Navarro-Taylor) . . . . . . . . . . . . 0-60 Shale (Nii-Varro-Taylor) . . . . . . . . . . . . . . . . . . . . . . . . . 60-390 Soft white lime (Austin) ..... . . . .... . .... . ...... 390-528 Lignite (or shale) (Eagleford) ......... . .......... 528-560 Hard white lime (Buda) .... . ..... . . .. ... . ....... 560-620 Mud hole (Del Rio) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 620-672 Light brown lime (Georgetown-Edwards) ........... 672-700 White to gray lime (Georgetown-Edwards) ......... 700-1000 118. Steves Irrigated Gardens, San Antonio. First water came to top at 1065-!070 feet. Drilled into water rock at 1185 feet when drilling had to be abandoned, on account of flow of water. Surface materials, water . . . . . . . . . . . . . . . . . . . . . . . . . 0-28 Blue clay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59-604 White clay or rock .. . . . ... . ... . . ..... ........... 604-728 Gray rock ............ .............. ... .... . . .. 728-. 780 Yellow rock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 780-805 Gray rock . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . 805-894 Geology and Mineral Resources of Bexar County 165 Sulphur water ...... . ........................ . .. 850 Lignite (Eagleford) . ....•.... .. .•...... . . . .... .. 894-922 Gray rock (Buda) ................. . ....... . . . ... 922-983 Mud hole (Del Rio) .............. ... ...... .... ... 983-10-11 Gray rock ............ ..... ..... ... .... . . .. .... 1041-1060 \Vater at ...... . .... . ....... ......... ..... .. ... 1065 Brown rock . . ............. . ... .. .... ......... . . 1060-1100 Brown hard flint .......... .. .. . ... .. ...... ..... 1100-1140 Gray hard flint? ................................1140-1160 Yellow hard flint? ........ .. ... . ... .. . ... .......1160-1185 119. Steves well, 509 King William St., San Antonio. Surface elevation about 650 feet. First sulphur water at 449; big flow at 742 feet. Surface 0-2 Hard pan ............ ...................... ... . 8-19 Gravel 19-34 Yellow clay .. ... . .. .. .... . ... . ....... . ........ . 34-42 Blue clay .. ...... ................... .......... . 42-250 Austin chalk ................. . ... . ........... . . 250-442 White limestone . ............ .. ... .. . . .. ...... . . 442-4i2 Yellow limestone .. . . ... . . .. .... . . ......... . .. . . 472-489 Gray limestone . .. . .. .. . . .. .... ...... .. ... .. .. . . 489-580 Lignite (Eagleford) ............................ . 580-613 Grtty limestone ..................... ........... . 613-082 Crystallized lime ............... . . ... . ..... . .. . . . 682-i34 Total depth ........... . ...... . . . ........ ... ... . 758 1~0. SteYes well, south of Chavanaux Road, west of S. A. & A. P. Ry. Benkendorfer, driller. Flowing warm sulphur water. The Del Rio clay in this well although not Yery definitely placed is r eported to lie 1790 feet from the surface, or at the level 11 30 feet below sea. This record places the formation nearly 400 feet lower than in the Alta Yista oil field. Scarcely more than a mile to the east-southeast. 123. Superior Oil Company, Linn farm, east of Palo Alto Road, 12 miles soutil of San Antonio. Fitzgerald, driller. Test well for oil. Oil sho"·ings as noted. Also warm flowing sulphur "·ater from the Comanchean formations. Black soil and clay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-14 Yellow clay ............ · · · · · . · .. · ...... .. ..... . 14-18 Yellow clay ...... · · · · · · · · · · · · · · .. · · .. · · · · · · .. · · 18-50 Yellow and blue clay ......... . .. . ... . . . ... . .... . 50-80 Blue and red shale . ... .. ... . . ...... .. ... .. ... . . . 80-l:l5 Shale ...... . . . · .. · ·. · · · .. · · ... ....... ........ . 125-145 University of Texas Bullet·in Greensand (set 178' 811 pipe) ....... . ... . ....... . 145-168 Tough shale ... ................. ........ ...... . 168-187 Shale and slate ................................ . . 187-263 Gas rock ... ... ................. ..... . .... .. .. . 263-275 Soft lime rock .......... .... .... ... .... . . .. .... . 275-279 Gas sand, hard .. . ... . ... .. .... . ..... . ..... .... . 279-282 Shale ......... . .... .. .... .. ............. . .. . . . 282-320 Lime rock . . ........... . ... ... ..... .. ... .. . ... . 320-328 Fine sand .... ... . ................... .. . ...•... 328-335 Shale with occasional boulders.............. . ..... . 335-420 Soft shale and white slate..... ................... . 420-500 Shale and soft slate .. ... .......... . ............ . 500-750 Soft white lime .. .... ..... ... ........ .... ..... . 750-753 Gypsum and shale ....... . ...... .. ............. . 753-758 Soft gray lime ... . .. .... ... ... ... .......... .. .. . 758-761 Shale .. .. .......... .. ....... ............. .... . 761-783 Lime and shale .. . ..... ... ...... .. .... . ... . .... . 783-796 Lime rock and pyrite of iron ........... . .... . .. .. . 796-800 Gypsum and shale .. . ................... .. ... . . . . 800-830 Lime rock ....... . ... . . . .... .. ................ . 830-834 Shale ... . ......... . .... .. .... . ......... ...... . 834-840 Lime, rock ....... . .. . ... ... .. . .. .. ...... .. .... . 840-853 Shale ................. ...... ............. · · .. . 853-855 Slate 855-873 Shale .. . . ......................... . .. ........ . . 873-904 Slate ............. ... · · · · · · · · · · · · · · · · · · · · · · · · · · 904-909 Shale .... . . . ..... .. .... . .... ... .... .... . .... . . 909-922 Slate .. .... .. . ... . . .. ........................ . 922-925 Rock, gray limes ............. ......... .. .. ..... . 925-926 Blue mud ............. ............... ......... . 926-950 Pyrites of iron ... ............ ... ..... .. ..... ... . 950-953 Rock, lime . ...... ... .. ... .... ... ......... ..... . 953-980 Oil-bearing sand . . . .. : .......... . . . ... ... . . . .. . . 980-985 Set 9 8 9 feet of 6'' pipe Soft shale and mud ..... . .......... .. .. .. .... . . . . 985-1020 White shale, strong gas .... .. .......... .. ........1020-1060 Oil-bearing shale . ... ..... .. ...... . . ...... . .....1060-1088 Rock, gray lime ...................... . .... .....1088-1125 Shale and slate ..... . .. . ... .. ...... .. .... . .. . ..1125-1200 Lime, soft ............ . . .. .. ................. ..1200-1235 Sand, showing little oil. . . .. . ..... ..... .. . . ... ... . 1235~1241 Slate and shale . .. . .. . . . ........... . .. ....... ...1241-1300 Soft shale, caving .. : ........ . .. .. . ....... ... . . .. 1:!00-1420 Slate .. ..... ... . . .............. .. .. . ....... ....1420-1430 Sof: lime .... . ..... .. .. . ..... . ...... .... . . . . ... 1430-14:!9 Shale and sand, soft, caving ......................1439-1500 Geology and Mineral Resources of BeJ:ar County 167 Slate and shale ... . .. .. .. ................. .. ....1500-15:.lO Soft blue shale, caving . .. .... ... . . . . .... . ..... ...1520-1557 Set 4" pipe Lime rock . . .... ... ...................... ... . .. 1557-1600 Blue slate ....... . ...... ... .. .. .. . . ... . ... .... . 1600-1635 Hard white lime .... .. ......... .. ....... . . .. .... 1635-1740 Honey-combed, soft lime, hot s•1lphur water . ... ... ... 1740-1800 Hard and soft lime ....... ........ ............... 180 0-2600 Oil sand, small showing of oil .... .... .......... ... 2600-2606 Hard blue lime ... ....... .... . .. . . ........... ... . 2606-2900 Little sand and fresh water .. .. ................. . 2 900 In this well a greensand horizon is reported a.t 145 feet from the surface. The Del Rio clay appears from the log to lie at about 1500 feet from the surface, the interval between the green sand and the top of the Del Rio here being 137 5 ft. while in the Kearney well nearby this interval appears to be 1326 feet. When reduced to actual elevations, the greensand horizon in the two wells is found to be about 20 feet higher in the Kearney than in this well. The well was drillE:d approximately 1500 feet into the Comanchean formations and hence probably terminates in the Travis Peak formation. Although not so stated in the log, one of the drillers on this \Yell reports that near the bottom of the well was fouud little altereu wood resembling cedar, similar to that tound in the Ridder well. 12L Terrell Hot ·wells, west of the Pleasan ton Road, 5 % miles south of San Antonio. Record published in U. S. G. S., 18th Ann. Rpt., Pt. 2'. p. 294. Flov;ing warm sulphur water, temperature reported to be 106~ F. From the record of this well it appears that the Del Rio clay was passed through here at from 1380 to 1425 feet or at the actual leYel of 7 5 O feet below sea. From these data the top of the Comanchean formations would be expected at about 1320 feet from the surface. Accordingly the whole of the Upper Cretaceous and possibly some of the Tertiary i£ penetrated by this well. At the depth of 600 feet from the surface were fossils identified by Dr. Hill as Gryphea ,·esicu1aris, indicating the Navarro formation. Brown coal, or lignite. is reported in this well at 140, 240, and 280 feet from the surface. The lignite suggests that the Wilcox may be present, extending into this structurally low area possibly from the southwest. 12;;. J. H. Terrell, at west city limits, 1h mile north of south limits of San Antonio. Sulphur water from the Austin at 765 feet; good water at 113 4 to 1140 feet. Gravel and yellow clay .... ... . . ........... ... .. . 0-60 Shale ....... . ................ . . .... .. .. . . .... . 60-550 Soft white rock ......... ... . ... ........ ... ..... . 550-903 Lignite (or shale) (Eagleford.......... .. ... . .. .. . 903-938 Hard white lime (Buda) ...................•...... 938-998 University of Texas Bulletin Mud hole (Del Rio) ............................ 998-1058 Brown and white lime ..... . .... . .. .. ..... . ... .. . 1058-1140 127. Louis Tezel, one mile north Culebra Road, 13 miles north­west of San Antonio. Goforth, driller. Actual level of Del Rio, 715 feet. Rock, not hard (Austin) ........................ . 0-55 Lignite (Eagleford) . . . ........... . . . . .... . . ... . . 55-90 Buda ... .. . . ... . .... ... ... . . . ......... .. ..... . 90-150 Del Rio .. . ....... .... .. ... ........ . .. .. ...... . 150-210 Rock (Georgetown-Edwards) .... .. .... .. . ... ... .. 210-245 132. Townsite well, Somerset. This well was drilled to the depth of 2002 feet many years ago, and of this part of the well no log has been found. Showings of oil were reported at 800-1100 and 1400 feet. During the summer of 1919 the well was deepened to 2320 feet by Dr. F. L. Thompson. From 2002 to 2030 feet no record has been made altho the drilling is said to have been in rock (Buda?). Below 2030 the samples indicate 70 feet of light blue clay. Altho no fossils were found this clay in general ap­pearance resembles the Del Rio formation. Below the clay from 2100 to 2320 the cuttings indicate limestones varying in texture and apparently representing the Georgetown-Edwards formations. The well terminated in strata containing a great deal of pyrite. While the data on tohis well are not as complete as desired it ap­pears probable that the Del Rio formation at this place lies from about 2030 to 2100 feet from the surface. The eleva;tion at the depot at Somerset as shown by the profile of the Artesian Belt Railway is 650 feet above sea. The elevation at the well altho not accurately determined does not vary greatly from that at the depot. Accordingly the Del Rio is placed provisionally at this locality as lying about 1380 feet below sea level. 13 5. Union Meat Compans, south Laredo street, between Ralph and Brazos. Sulphur water at 491 feet; good water at 1150 feet. Gravel and yellow clay . . . . . . . . . . . . . . . . . . . . . . . . . . 0-60 Blue shale . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60-340 White limestone ... ........... . .. . ... . ... . .. . .. . 340-656 Lignite (or shale) (Eagleford) ............ . ....... 656-686 Hard white limestone (Buda) ..................... 686-751 Mud hole (Del Rio) .............................. 751-820 Light brown limestone . . . . . . . . . . . . . . . . . . . . . . . . . . . 820-1150 White and gray limestone . ........ . ....... .......1150-1400 No water below . . .... . . . ...... .. ...............1250 137. Wm. Vogt, 1 % miles west of the Medina River and 1/2 Geology and Mineral Resources of Bexar County 169 mile north the Quintana Road. Flowing warm sulphur water from the Comancheau formations. In this well the greensand was reached at 2 9 7 feet from the surface, or at the level 308 feet above sea. The Del Rio formation was reached at about 14 8 5 feet and was found to be 5 2 feet thick. Water was obtained from the limestones at 1560 feet and succes­sively thereafter to the bottom of the well, 1850 feet. This well was drilled into the limestones belc;w the Del Rio 313 feet and hence terminates probably in the Edwards formation. The strati­graphic interval from the glauconitic greensand to the top of the Del Rio is here given as about 1188 feet, or 91 feet less than in the Ridder well. The record of the Ridder well is probably the more reliable. 138. )lrs. A. Voight, on the north side of Cu!ebra Creek, 14 miles from San Antonio on the Culebra Road. This well is !o­rated near the axis of the large structure described as the Culebra anticline. Surface materials and rathe:· soft rock (Austin) ..... . 0-35 Lignite ( Eagleford) .. .. .. .. .. . ....... ... .. .. . .. . 35-65 Bud a ... ............ . ....... . . ............. · · · 65-120 :\lud hole (Del Rio) ............... ........ : . .... . 120-180 Rock \Georgetown-Edwards) . . ..... ... ......... . . 180-216 Actual level top of Del Rio ....... .. . . ... .... . ... . 730 l:l9. 'Va1ing \Ye!!, on south side Bandera Road, about 11.'., miles northwest of San Antonio. D. Benkendorfer, driller. Non­ flowing artesian water probably from t_he Travis Peak formation. Soil ....... . . .. ...... ....... . . ........ .... · · . . _. 0-a 3-13 Adobe. lime and boulders . . . . . . . . . . . . . . . . . . . . . . . . 13-'iO Blne cla~· . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70-215 Yello\\· limestone ... ....... .... . . . . . .. ..... ..... 215-230 CreYic-e ................. . .. .. . . . . ... ... . .. . .. .. 230-2:12 \\"hite limestone ...... . .................... ..... . 232-265 Bi n<" clay . ..... .. .. . .... ....... .... . . . ... .. ... 265-275 \\"hite limestone . . . . .. ......... ............... . . 275-295 Blue slate ........ ............................. 295-32i> _.\dohe limestone . . ...... ........... ........ . . ... 325-33& White limestone ..... .... ....................... 335-370 Lignite (Eagleford) ... . .. .. .... .......... .. .. ... 370-400 White limestone (Buda) .. . .. . . .. . . ...... . ... .. . .. 400-460 ")Ind hole°' (Del Rio) .... .................... .... 460-510 \\" hite limestone .... . ... . .... .. . . ........... . . .. ;;10-530 CreYice "·ith water .... ........ . . ........ ....... . 530-532 Yello"· limestone . . . .. · ..... . . .... ... . . .......... 532-550 CreYic-e wit11 \\"'.\ter ..... ... ......... ... ...... ... . 550-555 University of Texas Bulletin White limestone ............................... . 555-600 White limestone ............................... . 600-615 Sand, brown limestone and water .. ........ ....... . 615-745 White limestone .....·..... ... ...... ........... . . 745-785 Brown limestone .. .. .. .. ~ ..................... . 785-795 White limestone .......... ; . .... .. .. ... ....... . . 795-815 Brown lim-:istone, water ....... .... .............. . 815-830 White limestone ............................... . 830-865 Brown limestone, water ......................... . 865-870 White limestone . ... .. . .. .... ..... . . .. ...... . . · .. 870-920 Brown limestone .............................. . 920~ 925 White limestone .......... .. ... . . . ..... ... .. . ... . 925-950 Crevice, brown limestone . . ...... ..... . . .. ... ..... 950-955 White limestone .... ... ......... . ... : . . ......... 955-1035 Brown limestone ............ ..... .. .. , . .... . . ... 1035-1080 Blue limestone .......................... . .. . ...1080-1190 White limestone ........... .. . ... .. ... .... .. .. . . 1190-1:!30 Blue limestone ..................................1230-1260 Blue slate . . . ... .. .... ..... ....... .. ...........1260-1262 White limestone ; ... . . ....... .. ....... ... . . .....1262-1455 Hard brown crystallized limestone .................1455-1478 Blue limestone ................ . ................1478-1505 Hard brown crystallized limestone .................1505-1510 White limestone .. .. .. . . ........... . .... .... . ...1510-1530 Hard blue limestone ...............·..............1530-1565 Blue limestone ....... . .. ..... .. . ... ............1565-1580 Brown limestone . ...... . ........... . .. ..... ....1580-1595 White limestone ................................1595-1635 Hard blue limestone ............. .............. ... 1635-1655 Brown limestone, white hard streaks .. .. ... . . . .....1655-1700 Hard blue limestone .... .. . .... ... . . .. . ... . . . . .. 1700-1715 Brown limestone ........................... ... ..1715-1735 White limestone . . . .... . . . .. ... ....... .. ........1735-1795 Hard brown limestone· ... .. . .... .... .. .. ...... ...1795-1860 Soft gray rock .................................1860-1870 Hard blue :::andy rock ......................... . . . 1870-1915 No description ..........•.......................1·9Hi-193 5 Mud ............................. . . ...... .....1935-1953 White limestone .. . ..... . ............... : ..... . . 1953-1985 ·Mud ....... .. .... .... .. ... . .... .. .... . . . . .. .. . 1985-1987 White limestone .. ..... .. ............ . ..........1987-1997 Mud at .. .... ......'. ............... '. ........... 2000 One foot of mud at ........ . .. . ....... . .. .. . .....2008 Hard limestone, shells and mud to ...... . .. ... .....2040 Soft white limestone . ... .... . .. .... . ........ ... . 2040-2070 Very hard sandy limestone ....... ... . · ... .. ..... . .. 2070-210(1 Geology and illineral Reso·urces of Bexar County 111 White limestone , .. .. .. . . .. ....... . . ... ... . ..... 2101!-2115 Mud ..................... ..................... 2115-2140 Limestone ..................................... 2140-2190 Blue mud .. .......... . . .. . .............. . . ... . . 2190-2483 Hard limestone, streaks of mud .. ................2483-2600 White sand . . . . . ... ... ........ .... ....... ...... 2600-2645 White limestone .. .. ............... . .. ...... .. .. 2645-2675 Dark limestone and sand . .... ... ...... ... .. .. . .. 2675-2699 Trinity white sand, water . ... ... .... ... ... ... .... . 2699-2705 Very hard cap rock ...... .. ..... ....... .. .... .... 2705-2711 Sand and hard streaks .. ............ ....... . .....2711-2784 Sondstone, very hard, filled with red mud . . ........ 2784-2810 Crevice . .. . ......... .. . .... . . ... ..... . .... .. .. 2810-2810 Sandstone shale .. . .... . .............. .. .... ... . 2813-2853 This \Yell is of intere~t as affonling apparently the maximum thickness thus far recorded for the Comanchean formations in this county. The Buda limestone was entered at 400 feet from the surface, and while no cuttings were preserved, it would appear from the log that the Cretaceous extends to 2 7 0 5 feet, if not to the full depth of the well. Assuming the base of the Cretaceous to lie at 2705 feet there is indicated a thickness of the Cretaceous of not Jess thrn ~300 feet. The age of the materials from 2705 feet to the bottonh of the "·eII. 285:3, is in doubt. Dirt taken from the dump around the well when washed and examined failed to show the presence of schists such as were found below the Cretaceou5 farther to the north , altho this test can not be assumed to be con· elusive as to the presence or absence of s~hists. \YELLS TER:\IINATING I!\ THE UPPER CRETACEOl'S Among wells terminating in the L:'pper Cretaceous the fol­lowing are listed as indicatiYe of conditions met with in drill­ing into these formations. The ''"ells entering the Comanchean as alread:· noted, are chiefi:· water wells. while those of the Upper Cretaceous are chiefly either oil-producing wells or wells drilled in testing for oil or gas. 145. Cohen & Roby. north of and near to the jog in the Dwyer r·ross road in the Gas Ridge oil and gas field. Depth, 1036 feet, Elerntion about 750 feet. Showings of gas between 170 and 249 feet, large gas production 865-990; showings of oil at 480, 492, 550, 615, i80, 815, and 1000-1035. Gravel ........... .... ... .. . . .. . . .... . ........ . 0-10 Yellow clay .... . . .... . ........ .. .... . . . ....... . 10-\JO Black shale ................................... . 9 0-10 0 University of Texas Bulletin Blue shale .... ...... ............... . .......... . 100-120 Light blue shale ........ . ...................... . 120-160 Dark blue shale ....................... .. ...... . 160-170 Shelly rock, gas . ............................... . 170-240 Blue shale .... .. ..... .... .... . ................ . 240-400 Small shell rock, first oil .. .. ...... .. ........... . . 400-444 Sand 6 inches ................................. . 444-450 Blue shale. ......... .... ...... . ...... ..... .... . 450-460 Shell of rock, oil sand .... .... ............... ... . 460-475 Oil sand ................ .. .................... . 475-498 Blue shale .. .......... ....... ... ...... . .... . .. . 498-500 Shell of rock, oil sand .......................... . 500-550 Blue shale 6 inches . ............................ . . 550-570 Small shell rock, oil sand 6 inches. .............. . . 570-615 Shell rock .................. . ................. . 615-650 Blue shale ......... .. ......... . ...... . ........ . 650-7UIJ Shell rock, more oil sand . . . .. ........... ... ..... . . 700-780 Blue shale .... . .... .. ......... .• .... ... .. .. .. .. 780-800 Smv.11 shell rock, more showing of oil .. . .... ... . . . . 800-815 Shell rock and gas ...... . . ........ ............. . 815-840 Blue shale .. .. . ... . .. . . .. . . . ........... . .... .. . 840-850 Large. shell rock, large gas .. ............. ....... . 850-865 Gas rock .... .. .. .. .. . ... ... .... . .. .. .. . .. .... . 865-890 Gas rock ..... . ........ ... ... .. ...... ......... . 890-990 Blue shale ...... .. ... . ....... . ... ... .... .. . . .... 990-1000 Oil sand .... ........ ....... ......... .. . ..... . . 1000-1035 This well starts in the Navarro formation and probably ter­minates in the Austin formations. The large gas supply at about 850 feet is probably in the Taylor formation. The heavy oil from this well at the depth of 1035 feet, analysis of which has been given, is probably from the Austin formation. 146. Crosby well No. 4, in Bexar County, north of Somerset. Soil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-16 Rock 16-20 Black gumbo ...... .... .. . ................... . . . 20-60 Rock ... ... ... . .... .. ................... . .... . 60-62 Shale ... . .... .. .... . ............... . .. . ..... . . 62-92 1.Vater sand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92-107 Gumbo ........ ... ............................. 107-132 Shale ........ . ............. ... .. . .. ... .. .... .. 132-262 Rock . .... . . .. . ..... .......... ... . ............ 262-265 Gumbo .... ... . . . ........ . .. . ..... ... ..... . .. .. 265-275 Water sand ...... . ...... . .. ..... ... .. . ... . .... . 275-293 Gumbo . ... .... . ..... . . ............ . ....... . .. 293-343 Rock .. .. . .. . ... ... .... .. ..... . ....... . ....... 343-:!47 Gumbo ... .... .. .. .. . .... ... .... . .. . . ... . ..... . 347-382 Geology and Mineral Resources of Bexar County 173 Shale .. ... ... .. . .. . .... .......... . .... ..... .. . 382-482 Gumbo ............. . ....................... . . . 482-552 Soft shale .... .... ............................ . 552-602 Gumbo ................................ · ... · · · · 602-682 Soft sandy shale ...... .................. .... ... . 682-742 Hard sandy shale, shell of rocks .. .. .. .. ....... . . . 742-1020 Very hard rock ... ............ .... .. .... . . .....1020-1022 Sand shale ....................................1022-1048 Rock ...................................... . . ..1048-1051 Shale and gumbo . ....... . . . ..... . .......... ....1051-1116 Shale .... . ... ...... . . . .... .. ............. ... .. 1116-1126 Gumbo ...... ... . .. ..... . . . ... ... . .. .. . ..... . .. 1126-1141 Shale .........................................1141-1181 Gumbo ..... . . ... ... ......... ............. ... . . 1181-1191 Shale .........................................1191-1217 Rock ................ . . .......... .............1217-1231 Shale and oil sand .................... . ....... .. 1231-1251 Gumbo .......... . .............................1251-1254 As in the case of other wells in the Somerset field, in Bexar County, this well starts in the Wilcox formation. The formation in which it terminates and from which oil is obtained is not definitely determined but is assumed to be either the Navarro or the Taylor. 147. Ingram well in the Alta Vista Field, drilled 1905, Jacob Wolff, driller. Depth, 1120 feet; 6" casing set at 960 feet, Greensand stratum recognized at 260 feet. ... . . .. 30 ft. thick This stratum according to Wolff made a barrel of oil per day, gravity 3 2 (some other tests reported the gravity 38). SE·cond stratum greensand at 700 or 740 feet, about . . 7 0 ft. thick Contained a good deal of gas and some oil. Made 2 % to 3 bar­ rels per day. Austin chalk rock recognized at 1000 ft. Heavy Alta Vista oil found at 1060 to 1080 ft. This heavy oil from a 5 or 6 foot crevice in the rock containing asphalt like material. Although not a producing well, this well is of intenst as the first well dri!led within the Alta Vista field in which a pronounced showing of oil was obtained. The well was drilled for water. The first producing oil well in this field was drilled about ten years later. 148. Wells of the Kimbly and Brown lease on the Swearingen property, south of the Medina River. The producing horizon is reported in the wells on this property at the following depths: Swearingen No. 1, located at north side of the property, producing sand at from 1210 to 1235 ft; Swear­ingen No. 2, producing sand at from 1216 to 1245 ft; Swearingen No. 3, producing sand at from 1248 to 1280 ft; Gale No. 1, produc­ University of Texas Bulletin ing sand at from 1360 to 1400 ft; Swearingen No. 4, producing sand at from 1425 to 1485 ft. The wens are listed in the order of their location from north to south or east of south. The dip of the formations is thus seen to amount to as much as 115 feet between wells No. 1 and No. 4. The distance between these wells is a little more than a mile. These wells start in the Tertiary. The formation in which they terminate is undetermined but may be either the Navarro or Taylor, The following log is of the ..<:imbly and Brown Swearingen No. 4. This is the southernmost and deepest of the five wells drilled in this field to the close of 1918. Log furnished by Mr. Brown. Soil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0-3 Red clay ..................................... . 3-27 Yellow clay .............. ; .................... . 27-50 Sand ... , .................................... . 50-80 Lignite . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80-81 Sand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81-140 Streaks of lignite . .. . .. ... ..... ...... . . ...... .. . 140-146 Sand .... ..... .. .............................. 146-200 Rock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200-208 Sand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 208-317 Rock .... ... ... .. .................. . ... . . . .... 317-323 Brown gumbo .................................. 323-386 Rock ...................... . ........ .. ........ 386-394 Shale, thin rocks .... . . ..... .... . . . ............. 394-490 Gumbo .......... .. . . .. . .. . ..... . .... ....... ... 496-575 Rock ....... . ................................. 575-581 Shale ... . . . ................ .. .... . . . . . ... . .... 581-750 Rock ......................................... 750-752 Gumbo ... . ................................... 752-880 Black sand, gas ................................. 880-900 Gumbo . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ll00-1395 Soft rock shows some lime . . .....................1395-1425 Oil sand ....... ... ..................... ..... ... 1425-1458 Gumbo ........................................1458-1462 149. Well of J. K. Lamb, drilled by Park Oil and Gas Co., west of Corpus Christi Road, about 2 miles south of the Medina River. Test well for oil. Surface sand .. .... ... . . . ...................... . 0-2 Red sandy .clay ......... ... .................... . 2-:rn Water sand and boulders ....................... . 20-112 Loose gumbo and boulders .. .. .............. . ... . 112-150 Gumbo .... . . .. .. . .... . ... ... ............ . .... . 150-160 Sand rock ................... . ................ . 160-165 Gumbo .................. .. ................... . 165-172 Geology and Mineral Resources of B exar County 175 Sand rock .... .............. ........... ....... . 172-174 Sandy gumbo ...................... ....... .... . 174-222 Sand rock .............. .... . · · · · · · · · · · · · · · · · · · 222-227 Gumbo (Set pipe at 265 ft.) . .. . . . . . .. ....... . 227-342 8 11 Hard sand rock .......... ...... ......... ...... . 342-362 Gumbo ..... ..... ........... · · · .. · · · ·. · · · · · · · · · 362-388 Sandy gumbo ...... ....... ................. ... . 388-392 Sandy gumbo ............. ....... .......... .... . 392-450 Sand rock ............. ..................... .. . 450-453 \Vater sand ...... ............................. . 453-460 Sand rock ....... ................ .... .. .... ... . 460-465 Sandy gumbo and boulders .... .................. . 465-505 Shale and gumbo ....................... ..... ·.. . 505-565 Hard rock : rnd gumbo .... .... ..... ...... ..... .. . 565-582 Sand rock ...... ........... .... .......... ..... . 582-587 Shale and boulders ........... .................. . 587-701 Sand rock ..... ...... ..... .... .... ......... ... . 701-704 Shale ... ........... ....... .....•.. ..... · · · . · · · 704-708 Hard rock .... ..... .... ............ ........... . 708-711 Shale ............... .... ......... ....... ..... . 711-720 Sand and lime rock ..................... ..... .. . 720-723 Shale ........................... · · · · · · · · · · · · · · 723-747 Sand rock .......... .................. ........ . 747-751 Shale ............. .... ............. .......... . 751-790 Sand rock ........ .... .. ............ .... ...... . 790-793 Shale ............ ..... .... .. · · · · · · · · · · · · · · · · · · 793-800 Sand rock .......... .... ...... ... ......... .... . 800-803 803-811 '3hale .. ....... ...... .......... · · · · · · · · · · · · · · · · Sand rock ........... ..................... · .. · · 811-815 Hard shale ....... ..... ...... ...... . . .... . . · . · .. 815-850 Sand rock ..... ....... .... ...... ...... ..... · · · · 85 0-853 Shale ........... .... ...... .............. · · · · · · 853-860 Sand rock ..... ............. .... ....... ....... . 860-863 Shale and rock .. ..... ......... ............ · · · · . 863-940 Gumbo ............. ........... ..... ......... . 940~ ·980 980-983 Sand rock ..... ........ ......... · .... · · · · · · · · · · Shale and gumbo .. ......... .... . . . ... ..... . . ... 983-987 Sand rock ... ..... ........ ..................... 987-1000 Shale and boulders ..... ....... ......... ..... .... 1000-10::!0 Gumbo .. ................... .......... ......... 1030-1046 Sand rock .. .......... ......... ... .... ......... 1046-1048 Shale . ...... . .. . ... .... . .. ·.... ... . ... ... . . . . .. 1048-1095 Gumbo (Set 611 pipe at 1118 ft) ........ ..........1095-1110 Coarse shale .. ....... ......... ........... ...... 1110-1160 Fine shale ....... ........... ..... ..............1160-1190 Shale (slight showing of oil) ..... ........ ........ 1190-1::!09 Rock ..... .. .. . ............ ... .......... . . . .. . 1309-·1313 Shale ....................•.. . ..... . .... . ......1313-1375 Gumbo .. ........ . . . . .. .... : ........ .. . .. . . .... . 1375-1385 Shale ............... ... .. .. ...... . ..... . . ... .. 1385-1450 Rock . . ............ ... .. .. ............ ...... .. 1450-1453 Shale . ............................ ~ ...........1453-1510 Gumbo ............. . ... . ..... . .. . ... .. ..... ... 1510-1535 R.ock ........ .. . .. .. . .... . . .. ....... "· .... ... . 1535-1538 Shale (Set 411 pipe at 1555 ft) .. ...... .. ..... .. . .. 1538-1600 White lime .......... . ... .. ....................1600-1620 Shale .......... .. .... . ...... . .... .. ......... . . 1620-1638 Rock ...... . ......... .. ....... ...... . .. .. ..... 1638-1641 Shale . ... ....... .. . .. .... ·. .. . .................1641-1661 Rock ......... . .. . . . .............. . ... . .......1661-1662 Shale . ................ .... .................. . . 1662-174.0 Rock ...... . . ... .. .. ... . ..... . .... . ... .. .... . .. 1740-°174~ Shale . ..... . ... . . ..... ...... . .... .. . . .. .. .... . 1742-1900 Black shale ...... . ...... .. .... . . .... ..... .. ... . . 1900-1940 Sand and shale . . . . ... . .............. . . .........1940-1980 This well starts in the Wilcox formation. The Austin forma­tion would seem, so far as can be judged from the log, to have been entered at about 1600 feet from the surface. Allowing for the Taylor and Navarro formations their usual combined thickness of about ·900 feet, there is indicated at least 700 feet of Tertiary at this locality. The Austin formation apparently is 300 feet thick, the Eagleford "black shales" having been entered at 1900 feet. Cuttings from this well were examined at the time the well was drilled, by Dr. J. A. Udden, who identified the Austin formation as extending from about 1600 to 1900 feet and the Eagleford below 1900 feet. If this Well terminates in the Eagleford at 1280, ru> seems probable from both the log and the cuttings, there is here the maximum thickness, 80 feet; recorded for this· formation in Bexar County. Assuming that the well terminates at or near the base of the Eagleford, the estimated level of the top of the Del Rio at this place is somewhat more than 2000 feet from the surface, or near 1500 below sea le"Vel. 150. Mars Discovery well, Alta Vista oil field. Elevation, 600 feet. Drilled in 1915, on Kelso tract, 8 miles south of San Antonio. Surface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0-2 Gravel ... . .. .... ... . ..... . .. . ... . .... .... .... . 2-4 Red clay .. ..... . · .. . ..... .. .. . ..... .. . .... .... . 4-16 Joint clay .... .................... ............. . 16-40 Rock lime ................................ . ... . 40-46 Yellow sand .... .. ... . ... .. .. ........ . ........ . 46-54 Blue. shale ... ....... . . ........................ . 54-70 Geology and Mineral Resources of B exar County 177 Sand rock, red ............. .. ...... · .... . · · · .. · · 7 0-72 Blue shale ............................ ·. · · · · · ·. n-110 Sand rock, rough .... .......................... . 110-113 Blue gumbo ..... . ..... . ...................... . . 113-133 Sand, showeth of 1892 feet and con­tinued to the bottom of the well, 2025. If the top of the Austin be .placed at 1892 feet, and from the drilleTs log apparently it ·can not be. olaced at any higher level, the Del Rio formation is to be expected in this well at a de·pth approximating 2342 feet, or near (he actual level of 1827 feet' below sea. The seemingly great thick­ness of the Tertiary in this well and in the Sarah Smith well, log of which is given later, indicates that a part of the interval assigned to the Upper Cretaceous in the Ridder, Kearney, and Superior Oil Co. wells may possibly also be Tteriary. LOG OF J. H. MATHEY WELL NO. 1 Bexar Petroleum Company, near Losoya, Bexar County, Texas. Elevation 515 feet. Commenced drilling Nov. 18th., 1919. 0-68 feet, red clay and small gravel. 68-7 4 feet, blue-gray sand rock. 74-78 feet, black gumbo. 78-80 feet, blue-gray sand rock. 80-100 feet, red clay and small gravel. 100-102 feet, blue-gray sand rock. 102-130 feet, red clay and sand. 130-135 feet, black gumbo. 135-180 feet, red gumbo and hard sand (water). 180-190 fEet, black gumbo. 190-201 feet, black shale. 201-208 feet, black gumbo. 208-222 feet, dry brown sandy shale. 222-224 feet, brown sand rock. 224-240. feet, black gumbo. 240-260 feet, dry brown sandy shale. 260-263 feet, shell. 263-290 feet, dry brown sandy shale. 290-293 feet, brown sand rock. 293-330 feet, brown sandy shale (dry and hard). 330-336 feet, black gumbo. 336-350 feet, brown sandy shale (dry and hard). 350-358 feet, black gumbo. 358-359 feet, gray sand rock. Geology and Mineral Resources of Bexar County 179 359-365 feet, black sandy gumbo. 3 6 5-3 6 7 feet, gray sand rock. 3 6 7-3 8 5 feet, black shale with lignite. 385-409 feet, black sandy gumbo. 409-44 5 feet, gray sand rock (water) (used roller bit) 445-465 feet, black gumbo. 4 6 5-4 6 6 feet, gray sand rock. 4 6 6-471 feet, black sandy gumbo. 471-4 7 2 feet, gray sand rock. 472-505 feet, black sandy gumbo and boulders. 5 O 5-515 feet, black shale. 515-519 feet, gray sand rock. 519-5 5 7 feet, black sandy gumbo and small boulders. 5 5 7-5 7 0 feet, black shale and lignite. 5 7 0-5 7 4 feet, gray sand and lime rock. 5 7 4-5 9 0 feet, black shale and lignite. 590-640 feet, black gummy shale. 6 4 0-6 4 5 feet, black gummy shale and boulders. 645-730 feet, black hard gummy shale. 730-740 feet, black soft shale. 740-770 feet, black hard gummy shale. (Some fossils). 770-815 feet, black hard gummy shale. 815-819 feet, black soft coarse shale, with green marl. 819-841 fe-et, black hard gummy shale. 841-850 feet, black soft coarse shale. 850-1084 feet, black hard gummy shale. 921-928. Core No. 1. 1084-1085 feet, gray hard sand. 1085-1090 feet, black hard gummy shale. 1090-1097 feet, black hard gummy shale. 1097-1117 feet, black hard gummy shale. 1117-1124 feet, black hard sandy shale. 1124-1127 feet, black hard gummy shale. 1127-1129 feet, gray sand rock. 1129-1165 feet, black hard gummy shale. 1165-1170 feet, brown hard sandy shale. 1170-1200 feet, black hard gummy shale. 1200-1202 feet, gray sand rock. 1202-1214 feet, black hard gummy shale. 1214-1215 feet, gray sand rock with pyrites. 1215-1360 feet, black hard gummy shale (Core 1320-1322) No. 2. 1360-1372 feet, black hard sandy shale. 1372-1407 feet, black hard gummy shale (Core 1402-1406) No. 3. 1407-1417 feet, black soft shale. 1417-1472 feet, black hard gummy shale (Core 1457-1459) No. 4. 147 2-1490 feet, gray shale with lime. (Lime only thin layers) . 1490-1548 feet, gray hard gumbo. University of Texas Bulletin 1548-1556 feet, gray hard shale. 1556-1570 feet, gray hard gumbo. 1570-1582 feet, gray hard shale. 1582-1600 feet, gray hard gumbo. 1600-1622 feet, gray soft shale. 1622-1632 feet, gray hard gumbo. 1632-1670 feet, gray soft shale. (Gas and little oil showing). 1670-1710 feet, gray hard gumbo. 1710-1720 feet, black soft gummy shale. 1720-1740 feet, gray hard gumbo. 1740-1763 feet, black hard gummy shale. (Core 1760-1763) No. 5. 1763-1820 feet, black hard gummy shale. 1820-1825 feet, black soft gummy shale. 1825-1840 feet, black hard gummy shale. 1840-1845 feet, black soft shale. 1845-1861 feet, gray hard sandy gumbo. 1861-1862 feet, gray lime rock. 1862-1870 feet, gray hard sandy gumbo. 1870-1885 feet, gray soft shale. 1885-1892 feet, gray hard sandy shale. (Set 6-inch casing at 1892), 1892-1938 feet, blue-gray chalk. (Showing little gas and oil) . 1938-2007 feet, blue-gray chalk. 152. National Oil Co., Alta Vista oil field: Depth, 1132 ; eleva­tion, 585. Producing horizon, Austin formation, 1120; sulphur water encountered at 1132. Actual level, top of producing sa'nd, 635 feet below sea level. Estimated position top of Del Rio clay, 835 feet below sea level. 153. Oliver well, 91h· miles southwest of San Antonio. Depth 1030 feet. Oil showing at 200 and at 600 feet. Strong gas fiow at 800 feet. Gas fiow reported to have been 350,000 cu. ft. per day at time well was drilled, subsequently probably reduced in fl.ow. This well orobably reached to the Austin formation; however, the showing of oil and the gas with little doubt is from the Taylor and Navarro formations. 154. Openheimer well No. 1. Alta Vista field, about 1400 feet northeast of Fuchs, No. 1. Smith, driller. Depth 1295 feet; eleva­tion 620. About 500 feet east of the Pleasanton Road. Producing horizon at 1150 feet. Sulphur water at 1295 feet. Actual level producing sand, 530 feet below sea. Estimated place of the Del Rio 830 feet below sea. 155. Park Oil and Gas Co. Applewhite No. 1 wen. North side of Rockport Cross-road, 11h miles east of Applewhite Road, 16 Geology and Mineral Resources of Bexar County 181 miles south of San Antonio on south side of T. C. Applewhite prop­erty. Thompson, driller. Depth, 1952 feet. Elevation 500 feet, more or less. Test well for oil. Clay ....................... · · · .. · · · · · · · · · · · · · · 0-50 Rock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50-51 Sand 51-60 Rock 60-62 Sand and boulders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62-80 Rock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80-82 Sand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... . . . . . . . . . . 82-90 Rock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90-98 Sand and boulders .... . . . ............. . . ... ..... 98-120 Rock ..................... .......... . . ........ 120-122 Sand and boulders ..... ...... ... ....... .. ... .... 122-150 Rock ........ ................................. 150-152 Hard sand ............................... . . . ... 152-200 Rock . .... ............ .. ......... ..... ..... ... 200-202 Sand and boulders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202-240 Shale ......................................... 240-275 Packed sand . ... ......... .... ......... ...... ... 275-280 Shale and boulders . . ......... . . .. ........ ....... 280-340 Packed sand and gravel .. . ... ....... ........... . . 340-370 Packed sand ...... ... . ... ....... . . .. . ... .. .. . .. 370-400 Rock .............. ................. . . . . .. . . .. 400-405 Shale ....... . . . ......... . .....·.... . .... .. . ... . 405-420 Rock ............................. ....... . . . . . 420-421 Rock (water sand) ...... . . ....... ........... .... 421-542 Sand rock ............................... . . . .. . 542-630 Shale ..... . . . ..... . . . .. . . ..... . . . ........... . . 630-675 Rock . ........................ .. . .. ..... . . . .. . 675-685 Gumbo .. ............ ... ... . . ...... .... . . ... ... 685-706 Rock ......................................... 706-715 Gumbo .... .... ...... ... . . . .. ............ . .. ... 715-740 Shale and boulders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 4 0-8 2 5 Gumbo .. ..... .... . ....... . . .. . . .... .. ... ... ... 825-885 Shale, boulders, oil and gas sand ........ . . . . ...... 885-940 Gumbo .... ........ . . ... . .. . . .. .. .. . . ........ .. 940-972 Hard shale .................................. .. 972-995 Gumbo . . .. . .. ..... .... .. .. ..... .... ... . ... . . .. 995-1011 Shale ... .. . . ........ .... ................... ... 1011-1020 Gumbo ................................. ... ... . 1020-1030 Hard shale ........... ....... .......... .........1030-1036 Gumbo and boulders .... . ..... ..... ....... .. ....1036-1048 Shale ......... . ......................... . .. ... 1048-1050 Shale and boulders, showing oil . . .. .. .. . ... . ... . .. 1050-1080 Gumbo . . . ......... . . .............. . . . . . . . . .. . . 1080-1110 Gumbo ....... ... ...... .. ......... .... .. .. . ....1110-1127 University of Texas Bulletin Rock ..............•......•.•...••......•...•..1127-1133 Gumbo . . .................. . ...... . .• ••. .. . ...•1133-1148 Rock (red sand and iron) .. .....................•1148-1155 Shale and oil sand, showing oil .... ............ .. .. 1155-1175 Gumbo . .... . .. . ...•.... .. ..... . ...............1175-1185 ·Rock .. .. ................ . ............•.......1185-1187 Hard shale ...·.. . .................... . .. . ......1187-1258 Gumbo .. . .................. .. .............•...1258-1262 (Set 1261 ft. 611 line pipe in cement) Gumbo ....... .. ................... . .....•.....1262-1268 Hard shale . .. . . . .... ........ .. ... . . . ... . ... . ...1268-1290 Soft shale ..............................•......1290-1380 Gumbo ...... : •.......................•........1380-1390 Shale and boulders ........ . ............... . .....1390-1425 Gumbo ................. .... ...............•..14251-1435 Shale and boulders ... . ..... . .......•.. . ....... . . 1435-1472 Hard sand ••....•.....•............... . ..... . ..1472-1491 Gumbo ...... . .•..•.............. .. ... . ........1491-1512 Hard rock .... . .. . ...·: . . ........... . .... .... . ..1512-1514 Shale showing oil .•.................. . . . ........1514-1524 Gumbo .................. ..... .... . ...........152it~l530 Rock ................... ... ...... . ........•...1530-1532 Chalk rock ............ .. ... . ....•........ .. .•.1532-1572 Gumbo ..·...... ..•• ............••... ...........1572-1598 Shale and oil sand (showip.g oil and gas ..... •......1598-1645 Gumbo .....•....•...... ....... ..••..... ...•...·1645-1655 Shale .......... . ..•............. : .•...........1655-1688 Gumbo ........ . ........ ... .....•..............1688-1710 Hard shale ...•................ •......... •.....1710-1715 Gumbo, white ...... .. . . . ... .....•..•... ... .•...1715-1720 Shale showing oil ....·.......-.............•.....1720-1730 Gumbo (Set 311 lines) .•...... ..............•....1730-1732 Shale (Oil show) . ; ..............•..............1732-1796 Shale .......•·•... . ....•. . ............•..... • •.1796-1809 Dark brown.sand and shale (Oil show) ........•••..180·9-1816 Shale ••........................•........•..•..1816-1827 Sand ........•...............•...•..•...........1827-1830 Gumbo ............•.... •.......-...............1830-1842 Soft shale .. .......•.. . ........•.•••...........1842-1847 Gumbo ••.•.•...........•.....•....•......•.....1847-1852 Sort shale .........•..••............••......•..1852-1857 Gumbo .•... . ••..••..............• . ...•• ; .•....1857-1862 Shale and hard sand ........•.•.••••............1862-1867 Gumbo ........••..........•..... • .•.•....•.•••1867-1874 Shale .........•.•.•.....•.•..•••••.•.....•••..1874-1877 Gumbo ......•••.•..••..........•.•••.•••.•..••1877-1886 Soft rock ••••..••• •••••....••.•••.•..•....••• •1886-1889 Geology and Mineral Resources of Bexar Connty 183 Soft shale . . ...... . .. . .. . . . ...... . ..... . . ... .... 1889-18116 .Chalk rock .............. ... . ... ...............1896-1915 Chalk rock ........... ... ................. .. ... . 1915-1934 Oil sand ............................... .... .... 1934-1952 The well starts probably in the Wilcox formation and to the depth of 1050 feet or more may be Tertiary, although one cannot be sure of this. The reference is chiefly because of the reported presence of boulders to that dpth. From 1050 to 1896 feet, so far as can be judged from the log, the Navarro and Taylor formations may very well be represented, their combined thickness being early 900 feet. The Austin formation appears to lie at about 1896 feet. If this is true the Del Rio may be expected at about 2350, or something like the actual level of 1850 feet below sea. 15 6. Perrinot well, about 2 miles southwest of Martinez, east of the Foster Cross-road on J. F . Schlather's property. Test well for oil. Soil .......................... . ............ .. . 0-2 Yellow clay ................................. . . . 2-22 Shale ............................ .. .. · · · · · · · · · 22-63 Rock .. ............. ........... · .. · · · · ·. · · · · · · 63-64 Shale and boulders ......... . ................... . 64-87 Shale .................... .. ........ · · · · · · · ·. · · 87-150 Gumbo .............. · .. · · · · · · · · · · · · · · · · · · · · · · · 150-236 Shale ........ ... ....... .. ..... .... ....... . .. . . 236-249 Gumbo ........................ . · · · · · · · · · · · · · · · 249-269 Rock ................ . .......... . .......... . . . 269-270 Shale .................. .... ........ · · · · · · · · · · · 270-297 297-307 Gumbo .............. · .. · · · · · · · · · · · · · · · · · · · · · · · Shale and boulders ............................. . 307-359 359-371 Gumbo ................ · · · · · · · · · · · · · · · · · · · · · · · · 371-391 Shale ............... · .. · · · · · · · · · · · · · · · · · · · · · · · 391-401 Gumbo ............. ·. · · · · · · · · · · · · · · · · · · · · · · · · · Shale ...................... . ..... .. .......... . 401-438 Gumbo .................. · · ...... · · · · · · · · · · · · · · 438-446 Shale ................·......... · · · · ·. · · · · · · · · · · 446-461 Rock ................ . .................. · .... . 451-453 Shale ..................... · . .. · · · · · · · · · · · · · · · · 453-478 478-483 Gumbo ........... · · · · · · · · · · · · · · · · · · · · · · · · · · · · · Rock .................. .. . . .. . ... · . . . . ....... . 483-492 Shale ........................................ . 492-591 Gumbo ............. ... ....... . ... ... ......... . 501-522 University of Texas Bulletin Rock Shale, oil showing .............._........ .. . ; .... ; Gumbo ............................... ·. · · · · · · · Rock : . ...... ·~ ............................... . Gumbo ................... · · · · · · · · · · · · · · · · · · · · · Rock ......................................... . Blue clay . . . . .........................'. ....... . Gumbo ...... . . ...... .. . ........... . ....... · .. . Rock ....... ......... .. . ... . .............. ... ·. Gumbo ............. ... ........ •........ .... ... Sand and shale .... ... ....... . ................. . Gumbo ....................................... ~ Rock . ... .. ............ ........ ... ..... ...·... . Shale, oil showing ........... .... .... . ......... . Gumbo ................... .................... . Shale and boulders ...... .. . . . ..... . . . .. . ...... . . Shale and gumbo . .. ... ........... . .. . .... .... . . Gumbo, very tough . ......... ........ . . ....... .. . Shale .... . ....................... -... -. .... .. . Gumbo .. .. .. . ...... ....... .. ............... . . . Shale and boulders .................... , ....... . . Soft rock ............................... . . .... . Shale ..... ... . ............. . ................. . Rock ............................ _ . ......... _. Gumbo .................... . .................. . R'ock -. ....................... . . ... ....... . .. . . Shale .................................. . ...... Black sand and shale, showing oil and gas . .. .... .... Gumbo ........ .. ...........•. . .... .. .......•. . Black sand and shale ...... ............... . ...... Rock . ......................... . ......... . .... Not recorded . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . Gumbo ....... . ................... . ... . ...... .. 522-523 523-534 534-547 547-.549 549-559 559-565 565-' 570 570-5·83 583-585 585-602 602-607 607-661 661-663 663-669 669-6H 684-709 709-730 730-761 761-774 774-779 779-789 78·9-806 806-816 816-827 827-8:!7 837-848 848-860 860-868 868-873 873-900 900-902 902-953 953-984 Shale ....... . ............... . .. . .... . . . ......... 984-986 Gumbo ......... . ......... : ... . ....... . ........ 986-1064 Chalk , ......... .. ......... .. ..................1064-1080 Shale .. , .................. . ........ . ........ ..1080-1107 Gumbo .. ................... . ......... . ........1107-1118 Shale ... ........... .. .... ... . ............ .....1118-1129 Gumbo .......................................1129-1134 Shale .........................................1134-1150 R.o<;k and shale .......... ...... ..... . ... ....... .1150-1162 Shale ... . . ........ •.... ........ . ...... . .......1162-1167 Gumbo .........· .... . ..•. ... ...................1167-1178 Shale ••......•........•................_. ......1178-;l.188 Gumbo •.................. '. ..... . ..............1188-_!193 Shale ... . ..... .. ..........•...................1193-1208 Geology and Mineral Resources of Bexar County 185 Rock .. . . ... ... ...... ...... .......... . . . ......1208-1212 Shale, show gas and oil .... ............... ....... 1212-1239 Chalk rock ...................... .............. 1239-1375 This well starts in the Tertiary, probably in the Midway forma­tion, and extends into but not through the Austin formation. The dividing line between the Tertiary and Cretaceous can scarcely be determined from the log, although the Midway may provisionally be regardetl as extending to 360 feet, as this is the last record of boulders suggestive of those of the Tertiary formations. From 360 to something more than 1200 feet is apparently referable to the Navarro and Taylor formations. Below about 1239 frnt, the drilling record indicates the Austin formation in which the we!l terminates. Assuming that the top of the Austin formation lies at about 1250 feet, the Del Rio at this locality is to be expEcted at about 1700 feet below t11 e surface or at about the actual level of 1000 feet below sea. 15 7. Porch well, east of the Pleasanton Road between Mit­chell's Lake and the :\Iedina River on Arroyo Hondo. Depth, 1505 feet; elevation about il30 feet. Test well for oil; showings of oil at about 1000 feet, and from about 1292 to 1493 feet. No water except small amounts bet\Yeen 60 and 70 feet, and a little salt water M the bottom of the hole. Record submitted to Bureau Of Eco­nornic Geology by E. L. Porch. Soil and clay ........... ......... ..... ........ . 0-30 Hard pan .................. · · · · · · · · · · · · · · · · · · · · :rn-vu Soft sand rock .......... . . ......... . .. . ..... .. . ;)0-P.0 Gravel, loose; water ............................ . t.:0-66 Very hard rock .. . . . ............... . ......... . . . 66-69 Sand fine, black ... .......... ..... ............. . 69-72 Clay, 10" casing set at 81' .................... ... . 72-87 Lii;nit.e ... .............. .............. ....... . 87-90 Sand rock . . . ... . . ....... ... . . ............ . . .. . 90-l:l 5 Very hard sand rock, gray . . .. . . .... ...... . . . . . . . . 135-137 Sand rock . . . . ............ . . ..... .... ....... . . . 137-164 High grade lignite or coal .. ...... ........ ....... . 164-172 Sand rock . .... .. .. . ......... . ..... . ...... . · .. . . 172-182 Hard rock ............................. ....... . 182-184 Shale ... ......... ......... ...... ............. . 184-193 Hard sand rock, blue ............... ............ . 193-203 Shale ...... ....................... .... .... · .. · 203-213 Gumbo . .. . .. . . ... ... . . . . . .................... . 213-286 Shale and boulder ................ .... ......... . 286-297 Rock, hard .. ............... . .. .. . . ..... . . .. . . . 29 7-299 Gumbo, Yery stiff ...... ..... . . . .. ... ...... . . . .. . 299-::!09 Rock, very hard . . ... . . ...................... . . . 309-312 Gumbo ..... ............. · · .. .. · .............. . 312-::!33 University of Texas Bulletin Sand rock, soft .... . .......... . ................ . 333-353 Hard blue rock ........ . ......... . ... . ... . .... . . 353-355 Gun:ibo ... . .•................................. 355-362 Hard rock . . ............... ... . .. . ............ . 362-364 Gumibo ...... . ....... . ....... . ............... . 364t 379 Boulder, flint ................................. . 379-.3 81 Gumbo ....................... . .. ; ..... . ..... . 381-3;87 Rock, hard . . ..... . . . ......................... . 387-389 Gumbo, tough ....... ........ ... .......... ...... . 389-409 Rock ........................ .. ................ . 4'09-410 Gumbo .......................... .. ........... . 410-417 Rock •....................... . ................ 417-420 Gumbo .. ...................................... . 420-454 Hard rock ............. . ......... .. ... . ....... . 454-456 456-473 Gumbo ...•.... · · .. · · · · · · · · · · · · · · · · · · · · · · · · · · · · Rock .................. . ....... . ............. . 473-474 Gumbo, very stiff ...... . ........ .. .... . . . ..... . . 474-492 Boulder ...............•....................... 492-494 Gumbo ... . ........... . ....................... . 494-518 Gumbo and shell .. . . ..· .... . ..................... . 518-523 Very hard rock . ............. ..... ............. . 5-23-526 Gumbo .... . ........... . .... . ................. . 526-544 Shale and boulder ..... . ...... . ............... . . 544-565 Gumbo with boulder ..... . ............... .. .... . 565-595 Gumbo and shell (Cretaceous) . .• ........ . ... . .... 595-609 Shale with boulders ... ... ....... .. . . ....... .. .. . 609-627 Rock ........... . ..... . .... . ................. . 627-629 Gumbo ........... ... · · · · · · · · · · · · · · · · · · · · · · · · · · 629-637 Shale ................ . .............. ... ... . .. . 637-647 Gumbo and boulder .......... . . . ...... . ... . ... . 647-671 Shale and boulder ... . ....... . . . ... •. .. •. .... . .. 671-689 Gumbo ........ : .. . .......... . . . . . ......... . . . 68·9-705 Rock ............................. . ...·...·.... . 705-706 Shale and shell .... . ... . ....................... . 706-719 Gumbo ...•...........•.......•...... . ......... 719-775 Shale and shell ........ . ....... . ............... . 775-791 Gumbo .... .. ....... . ..... . ... .. . . ... · · . . ·• ·. ·• 791-865 Shale .. . . . ......... . .... · .............. · · · · · ·. 865-·g72 Rock ......•.....•........................•.... 872-874 Shale, .blue .......................... . ......... . 874-881 Gumbo .•............ .. . . ..................... 881-888 Shale ........ . ............ . ...... . ........... . 888-892 Gumbo, light colored .... . .••.. . ....•. . ...•...... 892-894 Shale, coarse, blue .. . •................ , ........ . 894. 897 Rock, soft .. . ............... . ....•... . ......... 897-898 Shale and boulder .......... . .................. . 898-904 Gumbo ................. · · · · · · · · · · · · · · · · · · • · ·: · 904-966 Geology and il:lineral Resources of Bexar County 187 Shale, some soft ..... ... ............... . ........ 966-985 Shale and sand ... ......... ... ..... ......... .... 985-1003 Gumbo ..................... .. ...... .. .... . ... 1003-1056 Shell and rock ...... ......................... .. 1056-1058 Gumbo .. .. ...... . .. . .... . ........... . .. . ......1058-1129 Shale and sand, compact ..................... .... 1129-1133 Shale ..................................... .... 1133-1138 Shale, with large proportion of green sand ..... ..... 1138-114 8 Shale and darker sand ...................... ..... 1148-1157 Gumbo, dark sand, very fine ........ ............. . 1157-1171 Boulder ... ...... ..... . .. . ................. . . . . 1171-1172 Shale . . . ...... . . ..... . .. . .......... . .. . . . . . ... 1172-1175 Gumbo ........... ; . .. .. . . . .. . . . . . .. ... ........1175-1180 Boulder ......... . ... . ............ . .. .. . . ......1180-1181 Gumbo . .............. . . . ......................1181-1192 Boulder or rock ............·......... . ..... . ....1192-1193 Gumbo ...... . ...... .. . . ............ . .... . .... . 1193-1208 very fine shale ....... . ............. ..... .......1208-1213 Gumbo with pyrites ...... .. . . ............ . . .. . . . 1213-1233 Gumbo, tough blue ... . .... ... .... . . ... .. . .... . . . 1233-1292 Shale, gas and oil showing ....... ........ ...... ... 1292-1296 Soft shale and sand, gas ............. ........ ... .. 1296-1329 Shale or gumbo and sand ........ . . . ... . .... . ... .. 1329-1394 Gumbo, blue, no sand ..... .......................1394-1430 Shale and sand, gas and oil .... .. .... . ............1430-1464 Oil sand, little shale .......... ................... 1464-1483 Very dark shale, sand .... .. ...... . ....... . ... . . . 1483-1493 Dark blue gumbo and sand, very hard ............ .. 1493-1505 Supplementary data from owners of well: "From 1296 to 1394 the shale or gumbo was in alternate layers of about six inches, sand between; drilling was hard, while in the shale or gumbo and would go quickly through the sand. From each sand layeT fine showings of gas and some oil were noticed. Five joints of Layne & Bowler screen were set to catch this, but was too coarse. A fine black sand came through and formed a bridge and would form as fast as was washed out. The oil sand from 1464 to 1483 would undoubt­edly have made a well if same had been properly cased and washed. Live oil of light gravity and parafine base came out continually while going through with heavy gas pressure pieces of parafine as large as end of thumb came up with cuttings. In this well there was no evidence of Austin chalk which was struck in other wells 3 miles to the northwest at 1100 to 1200 feet ; other sections show shallow oil ahd gas, none noticed in this well until about 1000 feet down; no water encountered except between 60 and 70 feet, although a little salt water s·howed up from the bottom of the hole." University of Texas Bulletin 158. Log of Oil Prospecting Well of W. C. Steubing, 2 miles southeast of Somerset, Bexar County, Texas. Sarah Smith No. 1. (Prepared by L. w. Stephenson from samples furnished by the owner; fossils identified by C. W. Cooks). T~ickness Depth feet feet 1. Reddish brown, slightly ferruginous, fine sand .. 4 4 2. Light gray, very fine argillaceous, micaceous sand blotched with yellow . . ..... . ....... . 16 20 3. Fipe gray sand like No. 2 but more completely blotched with sulphur yellow and some pur­plish tint ............ .. ...... .. ....... . 20 40 4. Dark gray finely sandy, micaceous, carbona­ceous clay with fragments of fine reddish to yellowish ferruginous sandstone ..... . .... . 20 60 5. Gray fine slightly calcareous sand with some mica and numerous reddish, yellowish and brownish grains; water bEaring . . . . . . . . . . . 20 80 6. Gray Si!nd like the preceding, but contains numerous small, white flaky grains that are probably rotten shell fragments, as they effervesce freely in acid; water bearing .. ... . 20 100 7. Fin.e gray clean sand with pinkish and yellow­ish grains, and some mica; water bearing .... 20 120 8. Dark gray fine micaceous sand with numerous fragments of gray shaly clay ........ . . .. . . . 20 140 9. Fint gray calcareous sand with some mica and numerous dark grains; water bearing .... . . . 20 160 10. Gray sand like No. 9; water bearing..... . .. . 20 180 11. Fine gray clean sand, with some mica and · numerous dark grains ; water bearing . . ... . . 20 200 12. Gray sand like No. 11, but contains small fragments of gray shaly clay and small frag­ments. of vein calcite; water bearing ...... . . 20 220 13. Fine clean sand like No. p, with a few frag­ments of shaly clay; water bearing ........ . 35 255 14. Ground-up gray hard slightly calcareous sand­stone .. .............. · ... · ·. · · ... · · · · · · 4 259 15. Fine gray clean sand with some mica and nu­merous dark grains .. . . _. ..... . ..... ... .. . 20 279 16. Gray sand like No. 15 . . , .... •........ ... . 12 291 17. Ground-up light gray me1lium grained sand­stone ..... ............ , ............... . 21 312 18. Sandstone like No. 17 .. .... . . .. .....·... . . . 10 322 ~ 9. Fine gray sand with some mica, numerous dark grains, numerous fragments of gray Geology and Mineral Resources of Bexar County 189 Thickness Depth feet feet shaly clay, and small particles or black lignite . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 2 344 20. Light gray clean sand with numerous dark grains and small fragments of black lignite. . 31 3 7 5 21. Dark gray argillaceous, sand with some mica and some fragments of gray shaly clay. .... . 22 :197 22. Dark gray to blackish, finely sandy carbona­ceous clay, containing som€ marcasite. . . . . . 16 413 2 3. Dark gray carbonaceous clay mixed with fine gray sand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 437 24. Mottled mixture of fine white and light gray partly indurated sand, the cementing sub­stance apparently being white and gray clay; some fragments of gray shaly clay . . . . . . . 21 4 5 8 25. Mixture of fragments of dark gray shaly clay, and white sandy clay (?) . . . . . . . . . . . . . . . . . 20 478 26. Mixture of dark gray calcareous sand, frag­ments of dark gray shaly clay, and black lignite . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . 20 498 27. Mixture like No. 26 . . . . . . . . . . . . . . . . . . . . . . 21 519 28. Mostly fragments of gray shaly clay, with some loose fine gray sand, and a few shell fragments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 5 3 8 29. Mixture of fine gray calcareous sand and frag­ments of gray shaly clay . . . . . . . . . . . . . . . . . . 19 557 30. Mixture like No. 29; some shell fragments . ... 21 578 31. Mixture like No. 30 . . . . . . . . . . . . . . . . . . . . . 22 600 32. Mixture like No. 30; some lignite and shell fragments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 6:a 33. Mixture like No. 30; recognized the fossil shell Toinostoma? sp-. . . .. .. . . . . . . . . . . . 17 638 34. Mixture like No. 30: some shell fragments and some marcasite. . . ..... . . . . . . .... .... 21 659 35. Mostly gray shaly clay with a fE"w shell frag­ments; recognized the fossil shell Ringicula dalli Clark? . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 680 3 6. Shaly clay like No. 35; recognized the fossil shells Cyclichna sp., Corbula sp., and Tur­ritella sp. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 0 7 0 0 37. Dark gray clay (gumbo of the driller) with a few shell fragments; recognizeu the fossil shell Fuses sp. cf F l\Ieleri Aldrich. . . . . . . . . . 21 7 21 38. Gray shaly clay . . . . . . . . . . . . . . . . . . . . . . . . . . 19 740 39. Gray shaly clay, with some shell fragments recognized Turritella sp. . . . . . . . . . . . . . . . . . . 21 761 University of Texas Bulletin Thickness Depth feet feet 4 0. Gray shaly clay; recognized the fossil shells, Olivella medial'fa Harris, Natica sp. Turri­tella sp. . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 782 41. Gray shaly clay, larger fragments; recognized the fossil shell Pleions rugata (Hilprin) ?? . . 1'9 801 42. Dark gray clay (from bit?)...... .. ......... 21 822 43. Gray finely shaly clay . . . . . . . . . . . . . . . . . . . . . 21 843 44. Gray shaly clay; recognized the fossil shells Venericardia, sp and Nati.ca sp.. . . . . . . . . . . . . 2:2 865 45. Gray shaly clay; larger fragments . . . . . . . . . . . . 20 885 4 6. Gray (finely shaly clay with a mixture of dark glauconitic sand; recognized the fossil shells Venericardia sp., and Turritella sp.. .. ..... . 21 906 47. Gray shaly clay and glauconitic sand, like No. 46 ................ . .... · .. . . · .. · · · · 20 926 48. Gray shaly clay and glauconitic sand like No. 46 .................... . ..... . .. . . . 21 947 49. Gray finely shaly clay .... . ..... . ........ . . 21 968 50. Gray finely shaly clay with some dark glau­ conitic grains and some shell fragments .... 21 989 5l. Gray shaly clay, slight showing of oil and gas .. 23 1012 52. Gray shaly clay .with some glauconite grains; recognized the fossil shell Venericardia plan­icosta Lamark. Some showing of oil and gas .. 21 1033 . 53. Shaly clay like No. 52, slight showing of oil and gas .......... . .................. . 22 1055 54. Shaly clay like No. 52, gas and oil showing increase \. . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . 4 ·1059 According to Dr. Cooke, the fossils enumerated in the log indi­cate the Midway Age of the containing beds. Continuation of Log of Oil Prospecting Well of W. C. Steubing (Sarah Smith No. 1) 2 miles southeast of Somerset, Bexar County, Texas. (Prepared by L. W. Stephenson from samples furnished by the owner)~ ·55_ Light gray to whitish, highly calcareous clay or argillaceous limestone ground to fine mud, with fragments of platy impure limestone.. 16 1075 56. Gray, calcareous somewhat shaly clay with some admixture of material like No. 55...... 20 1095 57. Gray, calcareous, shaly clay . . . . . . . . . . . . . • . . 20 1115 58. Gray, shaly clay like No. 57; observed 2 speci­mens of Foraminifera . . . . . . . • . . . . . . . . . . . . 21 1136 59. Gray, shaly clay, like the preceding, with a few shell fragments . . . . . . . . . . . . . . . . . . . . . . . . . 21 1.157 Geology and Mineral Resources of Bexa.'r County 191 Thickness Depth feet feet 60. Gray shaly clay like the preceding, with a few shell fragments, recognized Yenericardia? and a small smooth gastropod ............ . 20 11/i 61. Gray finely shaly, calcareous clay ....... . 20 1197 62. Gray calcareous clay like No. 61 .......... . . 21 1218 62. Gray calcareous clay like No. 61 ........... . 21 1239 63. Gray calcareous clay like No. 61 ..... .... . . . 21 123\J 64. Gray calcareous clay like No. 61 ........... . 20 1259 65. Gray calcareous clay like No. 61 .... ... .... . 20 1279 66. Gray calcareous clay like No. 61 ........... . 20 1299 67. Gray calcareous clay like No. 61 ........... . 20 1319 68. Gray calcareous clay like No. 61 .. ..... .... . 20 1339 Not represented by sample .. ... ... ... . ... . 11 1350 69 . Gray shaly calcareous clay ............. . 50 1400 70. Gray shaly calcareous clay ..... . .. . ...... . 20 1420 71. Gray shaly calcareous clay ............... . 14 1434 i2. Gray shaly calcareous clay ............... . 6 1440 73. Gray shaly calcareous clay with a little fine sand 4 1444 74. Gray shaly clay like No. 73 . .... .. .... .... . 11 1455 75. Gray shaly clay like No. 73 ............... . 5 1460 76. Gray shaly clay like No. 73 ............... . :lO 1480 77. Gray shaly clay like No. 7 3 .......... . .... . 4 1484 78. Gray shaly clay like No. 7 3 ............... . 5 1489 Not represented by sample .............. . . 5 149.1 79. Gray shaly clay like No. 73 . . . . . . . . . . . . . . . 5 1499 80. Gray shaly clay like No. 73; contains a Jma\l gastropod . ...................... .... .. . 4 1503 81. Gray shaly clay like No. 73 .. .. ........... . 21 1524 82. Gray shaly calcareous clay and very fine sand. . 20 1544 83. Gray shaly calcareous clay with some fine sand; one or two shell fragments . . . . . . . . . . 21 15 6 5 84. Gray shaly clay and some sand; like No. S3... 21 1586 85. Gray shaly calcareous clay and very fiue sand.. 1~ 1605 8 6. Gray shaly calcareous clay and very i;ne sand. . Zl 162 6 8 7. Gray shaly calcareous clay and very fine sand. . 20 1646 S 8. Gray shaly calcareous clay and very fine sand. . 21 HI 6 7 This set of samples (Nos. 5 5-8 8) is very much alike throughout. A fragment of a \·enei1cardia? from sarnpL3 :\To. 6') (depth 1lf:>7­1177 ft.) seems to indicate that the shaly clay at that depth be­lon?:s to the Midway group of the Eocene. Nothing was found below that depth to indicate that the well had passed from tne Eocene into the underlying Cretaceous. If it is all Eocene the strata of this age are thicker at this place than we had supposed. COPY 0:1' OBIGllfAL BEC:OBJ>S or SABa.:a: SMITH 1 Ilf J>BILLEBS' 'BO'l'E BOOKS. ...... ~ Well is located 2 miles in a southeast direction from Somerset, Bexar County, Texas, and is known· as ~ Sarah Smith Well No. 1. Owner, W. C. Steubing; Contractor, Robert Newton ; Driller, Wm. Allen. Well be­gun 9-30-18; completed Jan. 1919. Rotary rig used. Diameter at mouth 10 inches. Six-inch casing extends to a depth of 1060 feet; cemented. Size of hole below 6-inch casing 5% inches; 4% -inch liner extends from depth of 1046 feet to bottom of well. Recorded by W. C. Steubing, 806 West Woodlawn Ave., San Antonio, Texas. Sam· pie I Rock or Material I Oo!or I Hard or Soft I From No. 1 Sand----------------------­White----------SofL-------------------------------­ 0 2 Olat---------------------· Yellow---------· SofL-------------------------------­ 4 3 OlaY---------------------­Yellow---------· SofL--------------------------------­ 20 4 Shale----------------------· Dark__________ Soft---------------------------------­ 40 ~ ~:~~==:::::::::::::::::::: t:~g~::::::::::: ~~~~:::::::::::::::::::::::::::::::::::: :: 7 Sand---------------------­Light-----------Soft---------------------------------­ 100 8 Sand----------------------Dark------------SofL--------------------------------­ 120 9 Sandy shale_______________ Dark------------Soft---------------------------------­ 140 10 Sand---------------------­ Light-----------SofL-------------------------------­ 160 11 Sand-----------------------· Light----------· Soft ----------------------------------180 12 Sand----------------------· Light----------· SofL---------------------------------200 13 Sand----------------------· Light----------· Soft ______________:___________________ 220 14 Rock-----------------------· Light----------Hard------------------------------. 256 15 Sand--------------------Light-----------Soft-------------------------------· -259 16 Sand----------------------Light-----------Soft---------------------------------279 17 Rock-----------------------Light-----------Hard--------------------------------291 18 Rock-----------------------Light___________ Hard-------------------------------312 111 Sand---------------------•-· Light----------Soft----------------------------------322 20 Sand-----------------------Light----------· Soft---------------------------------34! 21 Sand and shale---------· Dark-----------· SofL------------------------------375 22 Shale______________________ Dark-----------· Soft----------------------------------S97 23 Shale_____________________ Dark-----------· Soft---------------------------------413 24 Shale-----------------------Light-----------Soft---------------------------------437 25 Shale--~--------------------Dark------------Soft---------------------------------41\8 26 Shale-----------------------Dark-----------· SofL---------------------------------478 27 Shale--------------------Dark-----------· Soft----------------------------------498 28 Shale---------------------Dark-----------· Soft--------------------------------519 29 Shale---------------------Dark-----------· Soft--------------------------------538 To 4 20 40 6() 80] lOOf 120] 140 160] 180! mJ 255 259 279 ·291 312 322 344 375 897 413 437 458 478 498 519 538 667 Remarks ~ ~­ ~ Water sand. ~­-<:<::! ~ 12" of rock at 150 ft. ~ ~ Water sand. ~ -"' b;j ~ ...... ~- ~­ ..... 30"' 31 i:l 32"' 33 !'< 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 iO il 52 53 54 55 56 "' 58 59 60 Shale______________________ Shale---------------------­Shale---------------------­Shale---------------------­ Shale_______________________ Shale________________------­ Shale--------------------­Gumbo--------------------­ Shale..--------------------­ Shl!le_------__ ______________ Shale_______________________ Shale____________-----______ Gumbo________ -----------__ Shale_______-----------_____ Shale______ _____________ ____ Shale__________ ------__ ----­Shale______ -------------____ Shale_----------__ ---------_ Shale__________ __ ---________ Shale_________ ______________ Shale____---________________ Shale_____________________ -.. Shale___ -------------_______ Shale---________ ____________ Shale__ ____________ ________ _ Shale_____________ ---------­ Shale__________ _____________ ~:~~::::::::::::1 Dark----------­ Dark-----------· Dark-----------· Dark-----------· Dark-----------­ Dark____________ Dark-----------­ Dark____________ Dark___________ Dark-----------· Dark___________. Gray_______ _____ Gray____________ Bluish gray____ Bluish gray____ Bluish gray____ Bluish gray____ Bluish gray____ Bluish gray____ Bluish gray____ Bluish gray____ Bluish gray____ Dark gray_____ Dark gray_____ ''""------------------__--1 D•uk "°'____ Shale_______________________ Dark gray_____ IShale-----------------------1 Dark gray______ Shale______________________ Dark gray_____ m:===========================~:\ Sott--------------------------------. Soft-------------------__ ------------_ Soft ------------------------------___ Soft------------------------------___ Hard--------------------------------­ Soft---------------------------------_ Soft--------__ ----__ ----------------_ Soft---------------------------------_ Soft-------------------------------._ Hard ________ __ ----__ ------___________ Soft-----------------------------_____ Soft_______________ ---------·-··------­Soft---------__ ---------------------._ Soft ___ ------__ --------------____ ___ __ Soft ---------__ ------------------___ _. Soft -__ ----------------------------__ Soft __ ---------------------------_____ Soft_--------------------------------_ Soft ___ __ __ --------------------------_ Soft_----______ ----------------------_ Soft-----______ ------------------_____ Soft---------__ ------------__ --------_ Soft-------------------------------.. _ Soft to 1090, hard to 1095__________ H•ffi '° U00, ooUu UW-UW_____­ Very hard 1115-25, 2" rock at 1134__ Very hard 1125-45, softer 1145-50, harder 1050-57. Very hard 1157-68, little softer 1168-77. 557 578 600 621 638 639 ® 700 721 740 761 782 801 622 843 865 886 900 921.i W7 968 989 1012 1003 1065 1059 1075 1095 1115 1136 1157 1178 600 621 638 659 680 700 721 740 761 7frt 801 822 843 &;5 886 006 V-2() W7 9G8 989 1012 1033 1055 1059 1075 1095 1115 1136 1157 1177 Ribs of 8uft chalky rock from 5• to u• thick. ~ Note small shells and pieces of others. ~ Rib of chalky Umestone 12" thick gumbo. Note the shells. Shale, some sand. Shale, shells, and sand. Shale and black sand. Shale and some black sand. Shale and thin ribs of rock l" every 6 to 10'. Shale and thin ribs of rock l" every 6 to llY. c ..... above c (Q <.:: ~ ~ ~ ~ ~· ~ a ..... to 6"' ~ to 6" c "' ~ Shale, black sand. Slight showing of oil ~ and gas. ~ Shale, 12" rock at 1002' some oil showiDJ:. ~ 2 ft. rock 10'26, 2 ft. rock 103'2. "' Slight oil showing. In 2 ft. of limestone. c Rib 4" thick. Extends in next sample. ...... Gas and oil showing. Increase under 4'' O;:j of rock. With 6" rock at 1066. Showing oil under-~ neath. ~ "i 2" rock at 1080--small showing oil under­neath. Q More or less oil saturation throughout c entire 20'. ~ Small amount shells, 6" streak of soft ;:s shale at 1036, with oil and gas. More ..,_ ~ or Jess saturations throughout 20'. More or less gas and oil throughout en-t;re length. ~More or less oil showing throughout tOentire length . C,;) Sam· ple­No. --1 61 62 63 14 65 66 Rock or Material Color Hard or ­Soft From 1­I 1-­Shale-----------------------1 Dark graY-----1 Very hard entire length-----------, 1177 Shale----------------------­Dark gray____ VerY bard---------------------------­11g7Shale----------------------­Dark gray____ Hard, requiring 3',» hours for 2Q'-­1217 Shale-----------------------1 Dark gray_____ Shale-----------------------1 Dark gray____ Hard tlrst 4' with 8" rock at 1242. 17' being much softer requiringl'h hours for 17 ft. Softer tlrst 10 ft., harder second 10 ft. Thin shell of rock at 1270. 1239 1259 Shale and soine sand-­Dark gray____ IMedium hard:-----------------------11279 'l'o -1­1197 llll7 1239 1200 1279 t:!gg ----­to 1269. Remarka -1-----------­ISteady drilling required 4 houra to finish 20'. 6" rock at 112, l" rock at 12U. Good show oll .at 1223. More entire length. underneath. I Spots of brown oll from 1249 I Quite a showing of gasneath rib of rock. Increase In saturation ofIOil showing In ditch !~creasing. 67 68 69 70 71 72 Shale and some sand__. Shale and some sand--­Dark gray____ Medium hard-----------------------­1299 Dark gray____ Medium hard-----------------------­·1319 Shale and some sand---1 Dark graY----1 Medium hard------------------------11339 Shale and some sand--­Dark gray____ Medium hard-----------------------­Jt>59 Shale and some sand---·! Dark graY----1 Medium hard------------------------11380 Shale and some sand----1 Dark irray____ Medium hard----------------------­1400 1319 1889 1359 1380 1400 1420 OU showing Increasing. Rollk 2• thick at 1834. No neath.. Took 1 hour and tor 2.0'.ISome better showing of oil balance of 20' about same as Sllght oil showing In entire lestreaks several Inches thick showings.IBetter showing of ·on. gas at 1392. 1400-gas In good fiow continuingth with ng for 2', 73 74. 75 76 77 Shale and. some sand____, Dark gray____!Softer at last end-----------------, 1420 Shale and some sand--­Dark gray____ Hard from 1445 to 1457----------­1440 Shale and some sand____, Dark gray____ Shale and some sand---· Dark gray____ Shale and sand--------· Dark gray____ Hard and soft streaka----------­.Soft to 1484, hard and 1oft In streaks. Soft; cuttings very fine and sandyIn appearance. 1460 148> 1503 1«0 1460 1480 1503 1514 then decreased In fiow for 7 formation grew hard. Good oil at 1434, continuing to 1444. Good oil from 1457 to 1462 whtion grew harder. Good oil shOwfng 1473'h Good oil to 1483 and good sat14911, then Pulled ·stem at 1503. showed well· for first Ill minutIng when Increased showing econtinued for 10 minutes wheuration to es of drill· vident and n showings ft., where en forma­ or less oil 6" rock at 1280-spots oil at 1270 under­Entire length shows oil. gae under­30 minutes at 1350, above. of better . Slight showing of Oil entire length. very good to 1480. Increased with gas for 2 ft. At starting again rlropped back to normal, continuing to 1514 with 11ome gas. ...... ~ ""' ~ ~­ "" ~ ~ ~ '"3 (I) ~ ~ ~ E. £ ;;· 78 ..... Ol '":-: 79 80 81 82 83 84 85 Shalo IShale Shale Shale Sandy Sandy Sandy Sandy !\IHI sand----------1 I>ark graY----· 1 SoH; cuttings very fine aud sandy I In appearance. Dark gray_____ Hoft.; cuttings coarser and less sandy In appearance. and s"nd---------· and s"nd___ ------­ D"rk gray_____ Softer first fi ft.; cuttings coarse I "s above. sand_____ __ ___ Dark gray_____ Softer, requiring not more 2'h I hours entire length. and j shale--------------1 Dark gray_____ ::;: ~~~~~~::~~~~~~:~~:~:~:::::~::j shale-------------­ Dark gray_____ shale______________ \ Dark gray_____ \ Soft first 7', hard 1683-38, soft 1638-43. shale_______________\ Dark graY-----1 Comparatively soft first 5', harder second 5'. 1514 l.524 1514 1005 15&l 1605 1626 1646 1"24 I 1544 I 1565 I 1586 1606 I 1726 1646 1668 Sec 11/U /18 work was resumed first half hour showing very good-Indicating accumulation, balance of distance normal. Normal amount of showing. No extra oil or gas. 1514 to 1544 drilled In 2 q".) c ~ hours. .,._. First 5 f.t. In 25 minutes, second 5 ft . In c l'h hours, third 5· ft. In 35 minutes, 1. hours. Decreased ~· oil showing. Entire l•ngth drilled In 35 minutes; cut­tings show more sand In panning. 011 i ~ showing Increased throughout length ~ and Into next length for first 6 ft. Wash water very thick, 1633 to 1638 very ~ hard, requiring 1% hours. 1638-43 re­"' c quiring 20 minutes, 1643-46 requiring 50 minutes. Increase of oll and gas after ~ softer streak. ~ First 5' requiring 40 minutes, second 5' hard for l'h', then softer balance oi ~ way. Oil showing very slight at this point. b;j l ~ .... cc CTI University of Texas B'lilletin 159. Walsch Oil Company, well No. 1 on south side of .Leon: Creek in Mission Oil Field, near the Applewhite Road crossing. This well starts probably in the Navarro formation, as indicated b'Y the greensand horizon near the surface. They probably termi­nate in the Austin formaiion and i!lustrate the character of drilling in the Mission oil field. Gravel . . . . . . . . . . . . . . . . . . . . . . . • • • • • • . . • • • • .• • • . • 0-18 Greensand and soapstone ...........•..••...•..•.• 18-40 Clay, blue ..•..•••.......••......•..•• • · • • · · • · · 40-60 Clay and gumbo .........•.............••.. •·. · · 60-80 Shale and rock, soft; a little gas ......••..••.••.... 80-97 Shale, a little oil ................................ . 97-130 Rock .............•..............•....•....... 130-132 Shale 132-134 Rock 134-136 Shale 135-140 Rock and sand . . . . . . . . . . . . . . . . . . . . . . . . . . • • . . . . . 140-165 Shale ....... : ..........•.........•..•..••..... 156-167 Rock .··. · ......•.......·~ .•••..•••••••••••....... 167-181 Mud and small boulders ..............••......... 181-192 Shale .............. : . . . . . . . . . . . . . . . . . . . . . . . . . . 192-250 Shale and mud ..••..••............•....•....... 250-350 Rock ·. . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . • 350-352 Gumbo ........ : ......•.......•....•.•........•. 352-360 Rock ..... •..........•...•...•..•..••....•..... -360-364 Gumbo and shale . . . • . . • • . . • . . . . . . . . • . . . • . • • . • . . 364-430 Rock • • • • • . . . . . • • • • • • . • • • •.• • . . . . • • • • • • • . . • . • • • 430-432 Shale • . • • . . . • . . . • • • • • • • • • . . . • . • . . • . • • • . • • . . • • • 432-441 Rock, hard and soft . . . . . . . • . . . • . . . . • • . • . • . • . . . . . 441-445 Shale and mud •.•.•.•........•..•·• • . • . . . . • . . . . • 445-523 Rock . • . • • . . . . . . • . . . . . • • . • • . • . • . . • • • • . • . • . • . • • . 523-530 Shale • • • • • • . . • . . . . • • • • • . . . • . • • • • • • . . • . . • • • • . . . 530~ 637 Rock •..•..............•,. . • • • . • . • . • . . • . • • • . . . • • 637-657 Shale . • • • . . • • . • . . . . • • . . • • • • . . . . . . . • • . • . • • . • . . • 667-661 Rock ·.. • . . . . • . . . • • . . . . . . . . . . . . • . . . • • . • . • • . . . • • • 661-666 Shale • . . • . • . . • . • • • . . • . . . . . • . • . • • • . • . • • . . • • • . • . 665-670 Gypsum .•.•.•......•....••••.•.•......•.••.•.•• 670-698 Rock 698-702 Shale 702-766 Rock 766-786 Shale 786-791 Rock ••.•..••.•..•.....•.•.•.••• · · •. • • ·• • · · • • •• 7·91-801 Shale •..•..•.•••••••••..•••...••.. ; ••..••••••• 801-SU Iron pyrite .•...........•.•••....••.•.•.••...•• 814-815 Shale .•.•.•••...•.•••.•.•••..•......••.•••...• 816-821 Boulders •......•..........•...•••.....••••.••• 821-824 Geology and Mineral Resources of Bexar County 197 Shale 824-835 Rock 835-853 Shale 853-861 Rock 861-869 Rock 869-876 Sha.le and pyrite .. .. ....... . .. . ................ . 876-893 Pyrites, hard ... .. .. . ........•.................. 893-902 Shale .. . . • ......•........................ ... . . 902-925 Rock ............... •. ................... . . . ... 925-9:17 Rock and shale ... . ... .. . .. ................. . ... 937-957 Shale .•.•..................................... 957-982 Rock, hard ........... ......... . . ... ........... 982-988 Rock and shale ....... . ........ . .. . ........ . .... 988-1002 Brown rock ..... . ............... . ...... . ... . ... 1002-1024 Shale and some iron pyrite ................... ... .1024-1067 160. Wolfe and Elder, Alta Vista Oil Field, depth 1286, Eleva­tion 600. Test well for oil. Samples from this well from 965 feet to the bottom were sub­mitted by E. L. Porch and described by Dr. J. A. Udden (Mns). According to Dr. Udden's interpretation of the samples the well entered the Buda limestone at 1270 feet and terminated in this formation at 1286 feet. From this record it would seem that the Del Rio formation is to be expected at this locality at between 1300 and 1400 feet, or at an actual elevation of between 700 and 800 feet below sea level. INDEX Page Ackerman, H. J., well of. ...143 Alamo .. ..... ... ..... . .... .. 8 Alamo Heights . . . . . . . . . . . . . 42 Alamo Portland cement.. ....108 Alamo Waterworks well . ...143 Alectryonia larva . . . . . . . . . . . 50 Allen, D. J., well.of . ........143 Alluvial deposits ....... . .. .. 72 Alta Vista oil field .. ... . 121, 122 Alta Vista siructure . . . . . . . . 85 Area of artesian flow .. .... .101 Artesian water . . . . . . . . . . . . . . 97 Artesian wells . . . . . . . . . . . . . . 98 Austin chalk, analysis of .. . ..109 Austin formation .......108, 116 oil from . .. .. .. .......122, 124 water of ..... .. . . .... .. . ..104 Austin Hills . . . . . . . . . . . . . . . . 16 Aviation Post, well at ...... . 37 Avicula ........ . . ... ..... .. . 43 Babcock Road . . . . . . . . . . . . . . 96 Baculices . ... ... . . ........ .. . 43 Baker, C. L . 8, 43, 52, 55, 58, ............ . . . .... . . . . 112, 115 Balcones escarpment .. 11, 13, 77 Bandera Road . . . . . . . . . . . . . . 95 Barbattia sp. . . . . . . . . . . . . . . . 43 Basement sands . . . . . . . . . . . . . 21 Basse, Ed. E., well of ...... . . 143 Beckman . ... ................ 26 Bern Brick Co. . ... . .... . ....112 Bend formation .. .. ...... ... 19 Benke, Kate, well of . . ... .. .. 144 Bentonite ........ . .. . ...... . 115 Berry, E. W. . . . . . . . . . . . . . . . 10 Bexar Count~', area of . . . . . . . 7 drainage .... .. ...... .. . .. . 12 literaiure on ...... . . . .. . . . 10 settlements in . . . . . . . . . . . . . 7 topography ........ ... . .. .. 12 Biering, H. T., well of.......144 13!ancJ Road ....... .. ....... 80 Blank, J. T., we]] of ... . .. ... lH Bluewing Club, well of ......145 Boerman, D., well of ....... .147 Bose, Emil .. ..... . ... ....10, 40 Bracl;enridge Coal Company ..119 Brackenridge Park .. Q, 81, 109 Brrnclle, H., well of ........147 Brooks Field . . . . . . . . . . . . . . . 8 Buda fo rmation ....31, 110, 116 "'P.ter 'Cf ..••... .. . . . . . .... 103 Budn limestone, analysis of...110 PageBuilding brick ........... ...112 Building stone ..............121 Bulimulus ...... .. .. ..... . 73, 74 Bulverde Road . . . . . . . . . . . . . . 91 Calcareous concretions . . . . . . 75 Caliche . . . . . . . . . . . . . . . . . 75 Ca.mp Bullis Reservation . . . . 19 log of well on .... ... . .......131 Camp John Wise .. . .. .. .. .. . 8 Camp Stanley . . . . . . . . . . . . . . . 8 Carbon dioxide in under­ gronnd water ..... .........107 Carrizo formation . . . . . . . . . • • 63 Carrizo sand hills . . . . . . . . . . . 18 Castroville Road .. ... .. 114, 117 Cave deposits ................ 73 Cement .. ..... ............... 108 Cenozoic ......... ... . . ... ... 54 Clamp, C. C., well of ... .....147 Clay ........................112 Climate . . ... . ..... .. . .. .. ... 13 Cohen and Roby, well of .. ..171 Collins' Gardens, well at .. ..148 Collins Mfg. Co., well of .... .148 Columnar section . . . . . . . . . . . . 20 Comanchean . . . . . . . . . . . . . . . . . 21 Comanche Peak formaii-0n . . . 24 Conception Mission . . . . . . . . . . 7 Concrete . . ........ . . . ..... ..116 Concretions . . . . . . . . . . . . . . . . . 58 Cooke, C. W. . . ......... ... . . 190 Cretaceous . . . . . . . . . . . . . . . . . . 21 Crosby lease, wells on ...... .125 Crosby well N"o. 4 .......... . 172 Culebra Road . . . . . . . . . . . . . . . . 95 Culebra structure . . . . . . . . . . . 83 Cyprina mediale . . . . . . . . . . . . 24 Del Rio clay ................ 110 Del Rio formation 28, 86, 87, U2 'lnte1· of .... . .... . ..... . ..103 Dei Rio Plain .. ... .......... 16 Dentalium ........... . . ... .. . 112 Deussen, Alexander 9, 22, 75, 129 D'ckiEson well ............ .. 148 Dips . .. . .. 43. 51, 53. 83, 113 Dnmhle, E. T. . ........ . .... 10 EJgleford formation, 34, 111, 116 water of ................ ..104 Earle .................. ..... 62 Economic Geology ....... ... . 97 Ed"·ards flint hills ...... .... 15 Ed,,·arc1s formation .. ~5, 110, .. ... . ... .. ...... . ... ..116, 120 Page water of ..................101 Edwards limestone, analysis of ... ..................• •. 120 Elephas ......... . ........... 73 Elevations . . . . . . . . . . . . . . . . . . 12 .Eocene . ... . .............•... 54 Exogyra arietina ......... .28, 29 costata .............50, ·94, 115 laeviuscula' ............ .40, 43 ponderosa ... .40, 41, 45, 47, 48 texana ..... ......•... ....... 25 Faulting .................. : . 29 Faults .......... '. ........... 77 Flood-plain deposits . . . . . . . . . . 64 Flowing artesian wells .... . . 102 Fort ·Sam Houston . . . . . . . . . . 8 well at ............. : ...22, 81 Fredericksburg Road . . . . . • . . 96 Friesenhahn, A., cave of .... 73 Frio Road .............·.... , -'93 Fuller's earth ...............114 Gartner, T. A. ••............ 22 Gas ....................-. .....121 Gas Ridge field ..........122, 123 Geological map . . . . . . . . . . . . . . 86 Georgetown formation 27, 110, 116 water of ..................101 Geunther Milling Co., well of.149 Glauconite ..... .. ....49, 5?, 117 Glenrose for:ina.tion ...•.••23, 116 wa;ter of ... :....· ..........100 Glenrose Hills .............. 14 · Goforth, A. E., well of ....38, 149 Government weir at Aviation Post ........... . .... : ......149 ' at Ft. Sam Houston 1 ••••••150 Green marl ......... '. . . . . . . . 49 Greensand, analysis of ......117 Grote, F., well of ...........·.151 Gryphea aucella .• . ..... . . . 40 micronata . . . . . . . . . . . . . . . . . 29 vesicularis . . . . . . . . . . . . . . . . 50 Gulf Coastal Plains . , ...... -10 Hamilton; H. L. . . . . . . • . . . . • 64 Harrison, Judd, well of ......151 Harrison property, wells .on..125 Hayes, C. W. . . . . . . . . . . . . . . . 75 \ Herff well ........••.... ; ...161 Hickory formation ·. . . . . . • . . . . 19 Hill ......................... 25 Hill & Roby, well of ...... . ..132 HiJ.1, R. T. . •• · •..•..10, 21, 60, 77 Hoffman Ranch, exposures on. 33 Hofheintz, R. H., well of .. . . 152 Holtz well •...•••...••••••.•162 Hot Well Hotel, well at . . ....153 Hydrogen sulphide in under­ Pa&e ground waters ....... .. ....106 Index to map entries . . . . . .. . 87 .Ingram well ........... . ....173 Kea_rney Oil & Pipe Line·Co., well of . . .... . ........ .22, 154 Kelly Field .............·. . . . 8 Kelly Field Plain . . . . . . . . . . . 70 Kimbly-Brown wells .........173 Kurz, C., wells of ............125 Lakeview addition, well in...155 Lamb, J. K., well <>f ....49, 174 Legler, W. F., well of .......156 Leona formation .. :. . . . . . . . . 69 Leon Creek, exposures on.51, 117 Leon Springs, Military Reservation . . . . . . . . ... . . . . . 8 log of 'Well on .•....•......129 wells on, .... . .............. 19 Lignite ...............•.••.•118 Lime .......'. .........·.....•.120 Limes'toiie .. . ..... . ...... . •.119 Liopsitha elegantula . . . . . . . . 43 Locke, J., well of .•...•.....156 Lorenz, Alex, well of .. : . . ....156 Lunatia pedernalis . . . . . . . . . . 24 Madison, R. M. . . . . . . . . . . . . . . 9 Map ........................ 86. Mars Discovery well ........176 Masterson, B. F., well of. . ... .1.56 Mathey well . . ....... .45, 54, 1.78 Matyear, Chas., well of ......157 , Medina ·Fuller's Earth Co .....114 well of .............•.... ~157 Medina Oil Co., well of ...•..167 Medina River, alluvial d&­ posits of . . . . . • . . . . . ..• . . . . . 72 exposures on .......... .68, ,62 Mercke, R., .well of . . . . . . . . . . 21 Mesozoic .. ~ .... ; . . . . . . . . . . . • 21 Midway formation .......54, 116 M!ldway-Wilcox Hills .... . ... 18 Mi!rsion Oil Field ........121, 123 Missions , . . . . . . . . . . . . . . . . . . . . 7' Monopleura ..........·. . . . . . . 27 Mt. Selman formation . . . . . . . 64 Nacogdoches Road .......... 91 National Oil Co., well of . . ..180 Navarro formation ..49, 112, . . ...................•.114, 117 oil from ...........•......122 water of ..................104 Non-flQwing artesian wells....102 Oil , .............-. .. ........121 Oliver well .. .. ..............180 Geology and Mineral Resources of Bexar Oottnty 201 'PageOpenheimer well ..... . .. ....180 Packsaddle schists . . . . . . . . . . 21 Pancoast, A. C. . . . . . . . . . . . . . 9 Park Oil & Gas Co., well of ..180 Pearsall Road ....... ..... 93, 117 Pecten .. .. .. .. ........ . . . ... 43 Perrinot well ....... ... .. ....183 Petroleum ........... ........ 121 Phillips, W. B....10, 108, 117 Phosphate . . . . . . . . . . . . . . . . . . . 49 Phosphatic pebbles, analysis of 118 Physiography . . . . . . . . . . . . . . . . 14 Placenticeras sp. . .... . ...... 43 Pleasanton Road .. . . ... .. ... 92 Pleistocene . . . . . . . . . . . . . . . . . . 64 Porch, E. L. . .. ............. . 123 Porch well .......... ........ 185 Potash .............. ... .... . 49 P.ctassium ................ ..117 Potranca Road . . . . . . . . . . . . . . 94 Pre-Cretaceous .. .. ..... . . ... 19 Pyrite, source of hydrogen sulphide ....... .......... . 108 Radiolites . . . . . . . . . . . . . . . . . . . 27 Rainfall ... ...... ..... ...... · 13 Recent . . ...... . .. .... ... . ... 74 Red Lands ............... . 16, 25 Requienia . . . . . . . . . . . . . . . . . . . 27 Ridder, A. J., well of . . 22, 49, 139 Road materials .............. 128 Sabre-toothed tiger .. . ....... 74 Saint Denis . . . . . . . . . . . . . . . . . 7 Saint Hedwig Road .. .. .. ... 92 Saint Louis College, well at ..160 Salado Creek ............32, 96 Salado Creek, section on . . . . 46 Salado River, springs of .....105 Salado Waterworks, well at ..160 San Antonio and Aransas Pass Ry., well of .. .. .. ....161 San Antonio City Water Supply, well of .. . . ..161, 162 San Antonio city well . . .... . 162 San. A~tonio de Valero, ~ Il1 l SSlOn Of • •.•• •.••••• •• • • I San Antonio Lime Co .. ...27, 120 San Antonio Portland Cement Co. . .. . ......... .. 108 well of ...... .............162 San Antonio River ..... .. ... 76 springs of . .... . . .. .... ....105 San Antonio Sewer Pipe Works . ...... . . ... . . ......112 San Antonio structure . . . . . . . 84 San Pedro Park .. .. . .40, 42, 105 Saunders Creek, exposures . . . 58 Sauer, George, well of .......163 Page Scaphites sp. . . . . . . . . . . . . . . . 43 Schists ........ . . . . ... .. .... 19 Shattuck well ..... : .........163 Shumard, Geo. C. . . . . . . . . . . .. . 10 Shumeier, Henry, well of ... . 163 Smith, Sarah, well of ....55, 187 Somerset oil field . . . . . . 121, 124 Somerset Road . . . . . . . . . . . . . . 92 Southern Ice Co., well of .. .. . 164 South Medina Oil field ......125 Southwest Land Corporation well of .................. ..164 Source of hydrogen sulphide . . 106 Springs ...... ....... ........ 104 Star Clay Products Co. . .....112 Stephenson, L. ·w. 9, 43, 45, .. ........ ...... ....56, 62, 188 Steubing, W. C., well of .... . . 187 Steve's Irrigated Gardens, well at .... ... .. . ... ......164 Steve's well ................165 Stratigraphic geology . . . . . . . . 19 Stream Terrace Plains . . . . . . . 18 Structural geology . . . . . . . . . . 77 Sulphides, oxidation of .... ..107 Sulphur water .............. 105 Superior Oil Co., well of ....165 Table of geologic formations. . 20 Tabulated data on wells .. .. . 136 Tapetate . . . . . . . . . . . . . . . . 7 5 Taylor formation 44, 108, 112, 114 oil and gas from ....122, 124 water of .......... ........ 104 Taylor-Navarro Plain ..... .. . 17 Taylor, T. N. . ... ..... : . . 10, 105 Terrell, J . H., well of .... .. . 167 Terrell Hot Wells .. ..... .. ..167 Tertiary, water of ..... . . . ..104 Tezel, Louis, well of .... ....168 Topography . . . . . . . . . . . . . . . . . 12 Townsite well ...........•.. 168 Travis, W. B. . . . . . . . . . . . . . . . 8 Travis Peak formation . . . . . . 21 water of ..... . ......... ...100 Trinity ..................... 21 Turritella ... . ..... . ... . .....112 Tylostoma . . . . . . . . . . . . . . . . . . 24 Udden, J. A. 9, 19, 22, 45, . . ........... ...49, 57, 110, 129 Underground water . . . . . . . . . 97 Union Meat Co., well of .....168 U. S. Geological Survey . . . . . . 9 Uvalde formation . . . . . . . . . . . 65 Vaughan, T. W...21, 25, 28, .. . .... ..... ........ 50, 69, 77 Venericardia .. . . . . . 21, 2 5, 2 8 Villa de Bexar, mission of. . .. 7 202 University of Texas Bulletin V Page Page ogt, Wm., well of ..........168 Wells entering the Pre· Voight, A., well of ..........169 Cretaceous formations ....•129 Volutillthes .................112 Wells terminating in the Van Ormy : . ............. . ... 58 Comanchean formations ...135Walsch Oil Oo., well Of ••••••196 In the Upper Cretaceous ...171Warm sulphur water ........105 Waring Estate, well on .•..22, Wilcox formation ...•57, 11.2, 116 .......... •.• .......38, 100, 169 lignite of .........118, 167 Well records .......•....~ ...129 Wolfe and Elder, well of .....197 UNIVERSITY OF TEXAS BUREAU OF ECONOMIC GEOLOGY AND TECHNOLOGY BULLETIN 1932. J. A. UDDEN, DIRECTOR 0 ~ zl u I Kn w :E L-------­ ........ 'V LEGEND o~ /~ r [~] [&] Low Terrace Carrizo u 0 [Pmt I ~ ., u 1[ ~ ·a; Middle Terrace Wilcox ~ a: I ~ Q) §] l (5 c. I ~ 0. High Terrace Midway :::> I ~ E3 Contours on the Del Rio Fault ~ CE] Navarro "'::> Rndu .,0