Browsing by Subject "Geology -- Texas"

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A partial report on the geology of western Texas
(State Printing Office (Texas), 1886) Shumard, George Gettz
Buried hill at Wilcox-Carrizo contact in east Texas
(University of Texas at Austin. Bureau of Economic Geology, 1951) Stenzel, H. B. (Henryk Bronislaw), 1899-
A recently discovered buried hill, at least 77 feet high, is composed of strata of the Wilcox group (lower Eocene) and covered on its flanks by cross-bedded sands of the lower Carrizo and at the top by level-bedded shales and silts of the upper Carrizo formation. Peculiar small funnel-shaped pits filled with Carrizo sand extend into the underlying Wilcox ball clay at the peak of the hill. Other extensions fill shrinkage cracks of the clay. These and other features of the contact demonstrate a disconformity at the base of the Carrizo sand caused by rejuvenation that occurred shortly before Carrizo sand deposition.
Comanchean stratigraphy of Kent Quadrangle, Trans-Pecos Texas
(University of Texas at Austin. Bureau of Economic Geology, 1958) Brand, John Paul
At the northern end of the Coahuila platform, the thinned Comanchean sequence consists of the newly named Sixshooter group of carbonate formations underlain by the newly named Yearwood formation. The Sixshooter group consists, in descending order, of the Buda limestone, the newly named Boracho limestone composed of the newly named San Martine and Levinson members, and the Finlay limestone at the base. Beneath the Finlay is the Cox sandstone, and beneath the Cox, the Yearwood formation, which consists of an upper limestone member previously called Rustler (Permian) and a basal conglomeratic sandstone member that rests unconformably on Permian formations. The Buda and Boracho are biostratigraphically correlative with the Washita group of central Texas; similarly, the basal part of the Levinson member and all the Finlay limestone are correlative with Fredericksburg formations. Whether any part of the Cox sandstone is contemporaneous with the Trinity group is speculative. The Yearwood is probably a Trinity, though possibly a Fredericksburg, correlative.
Considerations in the extraction of uranium from a fresh-water aquifer-Miocene Oakville sandstone, South Texas
(University of Texas at Austin. Bureau of Economic Geology, 1982) Henry, Christopher D.
The Miocene Oakville Sandstone is a major aquifer and uranium host beneath the Texas Coastal Plain. In 1976, approximately 6,000 acre-ft of ground water were withdrawn from the Oakville for municipal use. An additional but unknown amount was used for drinking water in rural areas, for livestock, and for irrigation. Potential sustained yield is many times greater. Present and future uranium mining by either surface or in situ methods could affect the availability and quality of Oakville ground water unless the mining is designed properly. This report discusses possible effects of mining, potential natural mitigation of these effects, and approaches to minimizing the impact of mining on the aquifer system. Conclusions are based on results presented in a series of reports, cited in following sections of this report, on physical stratigraphy, hydrology, and geochemistry of the Oakville Sandstone. Both solution and surface mining may affect the availability of ground water by altering recharge characteristics and permeability. Because the volume of the aquifer affected by mining is small compared with its total volume, availability of Oakville ground water will probably not be reduced significantly, except in wells immediately adjacent to a mine. Mining may affect the quality of ground water by introducing chemicals that are not indigenous to the aquifer or by inducing chemical reactions that do not occur naturally or that occur at much slower rates. For example, most mining companies no longer use concentrated, ammonium-based leaches because of known problems in restoring water to its original chemistry. Natural and induced release of trace elements such as molybdenum is known to occur, but the geochemical controls on mobility and potential mitigating reactions in the aquifer are poorly understood. Because the affected aquifer volume is small, any deterioration of water quality will probably be localized. Observations and recommendations are presented on (1) regional and local baseline studies, (2) determination of aquifer sensitivity, (3) methods and goals of monitoring during and after mining, and (4) need for research on poorly understood aspects of mining impact. Such impacts include chemical reactions and processes that affect the long-term release of trace elements.
Contributions to geology
(University of Texas at Austin. Bureau of Economic Geology, 1929) University of Texas at Austin. Bureau of Economic Geology
Contributions to geology, 1931
(University of Texas at Austin. Bureau of Economic Geology, 1931) University of Texas at Austin. Bureau of Economic Geology
Correlation of the Ogallala formation (Neogene) in western Texas with type localities in Nebraska
(University of Texas at Austin. Bureau of Economic Geology, 1959) Frye, John Chapman, 1912-
The Ogallala formation extends from the north side of the Pecos Valley northward across western Texas, Oklahoma, Kansas, and Nebraska into southern South Dakota. With its southern limit within the Edwards Plateau, it underlies the upland surface of much of the High Plains section of the Great Plains Province. The extensive fluvial deposits of Neogene age are widely exposed throughout the dissected plateau region that flanks the Rocky Mountains on the east. The deposits have yielded large faunas of fossil vertebrates and mollusks and an abundance and variety of fossil plant seeds. Relief on the sub-Ogallala erosion surface accounts for the range in thickness of the formation from a feather edge to more than 500 feet. The lithology of the formation from Nebraska to central western Texas is discussed, criteria for correlation are considered, and the work on fossil vertebrates, mollusks, and fossil plant seeds is briefly reviewed, with the purpose of correlating the Ogallala formation of central western Texas with previously recognized type localities in Nebraska. Classification problems are discussed and it is concluded that rock-stratigraphic subdivision of the Ogallala of Texas is not usable regionally, whereas floral zones are recognizable throughout the High Plains. Three floral zones recognized in the Texas Ogallala are correlated with the Valentine, Ash Hollow, and Kimball of Kansas and Nebraska.
Depositional systems in the Nacatoch Formation (Upper Cretaceous), northeast Texas and southwest Arkansas
(University of Texas at Austin. Bureau of Economic Geology, 1983) McGowen, Mary K.
The Nacatoch Formation of the East Texas Basin is the middle formation of the Navarro Group and consists of marine sandstones and mudstones derived largely from source areas to the northwest, north, and northeast of the East Texas Embayment. Terrigenous clastics were supplied to the Nacatoch Basin by a major northeastern dispersal system originating in southwest Arkansas. Three minor fluvial-delta systems contributed sediment in southern Red River, Delta, and Hunt Counties, Texas. Five facies are recognized in Nacatoch outcrops in southwest Arkansas: tidal-flat, tidal-channel, tidal-inlet- associated, shoreface, and shelf facies. In northeast Texas, a delta sequence occurs in south-central Hunt County, and shelf sandstones and mudstones are present in Navarro and Kaufman Counties. The lateral association of deltaic deposits and tidal-flat sequences, together with the type, scale, and distribution pattern of inferred tide-produced structures, suggests that tides within the upper microtidal to lower mesotidal range (3 to 8 ft; 1 to 2.5 m) occurred in the East Texas and North Louisiana Embayments during deposition of the Nacatoch Formation. The Nacatoch Formation in the East Texas Basin is restricted to the northern and western parts of the basin. The sandstone bodies trend mainly northeast to southwest in the northern part of the basin and north to south along the western margin. In the southern half of the basin, the Nacatoch Formation consists of mudstones. In the subsurface of the East Texas Basin, the Nacatoch Formation can generally be subdivided into nearshore and shelf deposits. Nearshore sequences include deltaic deposits in the north and the northwest parts of the basin that are located downdip from surface exposures of the same facies. Two thick net-sand axes, oriented perpendicularly to the outcrop belt, extend southward into the basin. Orientation of these sand axes changes abruptly to become parallel within the dominant northeast-southwest trend, suggesting that the delta was dominated by tides and waves. It is inferred that interdeltaic areas were sites of short barrier islands, broad tidal inlets with associated tidal deltas, and tidal flats. Offshore deposits can be arbitrarily divided into a lower and an upper sandstone sequence separated by 50 to 100 ft (16.6 to 33.3 m) of marine mudstone. Sandstone bodies of the lower sequence are elongate, exhibit gradational lower boundaries and abrupt upper contacts, and grade laterally into muddy sandstones and mudstones. Sandstones composing these depositional sequences are well sorted, calcitic, glauconitic, fine to medium grained, and contain shell fragments. The sandstone bodies are interpreted to be offshore bars, which have a geometry derived primarily from tidal currents. Sandstones of the upper sequence compose a fairly continuous sheet sand; textures and composition are similar to sandstones of the lower sequence. Tectonism, coincident with deposition, controlled local sandstone distribution patterns. Development of rim synclines concomitant with salt dome growth considerably affected the thickness and distribution of the Nacatoch Formation; for example, thick Nacatoch sections exist around Haynesville salt dome in Wood County, Texas. Other piercement domes associated with salt withdrawal basins that were active during Nacatoch deposition are Steen, Mt. Sylvan, East Tyler, Brooks, and Bethel. Few sandstones occur in the Nacatoch Formation in the southern part of the East Texas Basin. These thin, laterally discontinuous sandstone bodies do not threaten the hydrologic integrity of salt domes now being investigated to determine their feasibility for nuclear waste storage. Sandstones within the Nacatoch Formation in the East Texas Basin are important shallow oil and gas reservoirs. Hydrocarbon reservoirs from the Nacatoch Formation are restricted to the shelf-sand facies. However, hydrocarbon entrapment appears to be more a function of structural closure than of depositional facies. Hydrocarbons are produced from Nacatoch fields developed over the Van salt dome in Van Zandt County and along the Mexia-Talco fault system trend near the western margin of the basin.
Depositional systems in the Woodbine Formation (Upper Cretaceous) Northeast Texas
(University of Texas at Austin. Bureau of Economic Geology, 1971) Oliver, William B. (William Benjamin), 1944-
The Woodbine Formation is composed largely of terrigenous sediment eroded from Paleozoic sedimentary and weakly metamorphosed sedimentary rocks of the Ouachita Mountains in southern Oklahoma and Arkansas and subsequently deposited in a complex of nearshore environments along the margins of the broadly subsiding Northeast Texas Basin. Three principal depositional systems are recognized in Woodbine rocks--a fluvial system, a high-destructive delta system, and a shelf-strandplain system. Their recognition is based on a regional outcrop and subsurface investigation in which external geometry of framework sands was integrated with lithology, sedimentary structures, fossil distribution, and bounding relationships. Two components of the fluvial system, a tributary channel sand facies and a meander belt sand facies, are developed in the Dexter Member (lower Woodbine) northeast of a line from Dallas to Tyler. To the south and southwest, a high-destructive delta system is persistent throughout the entire Woodbine section. The three component facies of the delta system are: progradational channel-mouth bar sands; coastal barrier sands, deposited along shore adjacent to the channel mouth; and prodelta-shelf muds. The Lewisville (upper Woodbine) shelf/strandplain system, developed in the northern third of the basin marginal to principal deltaic facies, is composed of two facies: shelf muds and strandplain sands, accumulated along shore. Near the end of Woodbine deposition, but before transgression by Eagle Ford seas, emergence of the Sabine Uplift resulted in erosion of Woodbine sediments, which were subsequently redeposited along margins of the uplift as the Harris Sand. The close correspondence of Woodbine oil and gas fields with deltaic and strandplain sands suggests that on a regional scale facies distribution is as important as structure in governing the occurrence of hydrocarbons.
Devonian-Mississippian transition in central Texas
(University of Texas at Austin. Bureau of Economic Geology, 1957) Cloud, Preston, 1912-1991
The Devonian-Mississippian transition outcrops of central Texas are here described summarily and assigned to a new stratigraphic unit, the Houy Formation. The beds included are mainly Upper Devonian, but partly Lower Mississippian. Locally a basal fraction may be Middle Devonian. Although the deposits included are diverse and their associations complex, the maximum surface thickness so far known is only about 17 feet. The principal subdivisions, in their usual ascending order, are the Ives Breccia Member (Plummer in Bullard and Plummer, 1939), the Doublehorn Shale Member (new), and a thin unnamed phosphoritic interval. Commonly, however, one or more of these members is absent, and rocks not assigned to any member are present. The Ives Breccia Member includes lag deposits of detrital chert of varied age and source. The Doublehorn Shale Member includes black, fissile, spore-bearing shale of Late Devonian age which in a few exposures grades upward into shale of Early Mississippian age. The phosphatic beds are partly Late Devonian and partly Early Mississippian. Remnants of the Doublehorn Shale Member have been found only along the eastern side of the Llano region, but the other units are more widely distributed, and rocks assignable to the Houy Formation are to be looked for between Ordovician and Upper Mississippian deposits anywhere around the Llano region. Although most abundant in the upper beds, phosphatic inclusions occur locally throughout the Houy Formation. This gives a stamp of unity to the sequence and distinguishes it from the immediately underlying beds as well as from the overlying Chappel Limestone of later Early Mississippian age. The Houy is also a unit of more than average radioactivity and is readily detected in the subsurface by radioactive drill-hole logging. It correlates with the Late Devonian and earliest Mississippian black-shale sequences of other Midcontinent and Midwestern areas. Four of the six conodont zones (Hass, 1947; 1956a; 1956b) in deposits of this age in Ohio, Tennessee, Oklahoma, and Arkansas are recognized also in central Texas.
Epigenetic zonation and fluid flow history of uranium-bearing fluvial aquifer systems, South Texas uranium province
(University of Texas at Austin. Bureau of Economic Geology, 1982) University of Texas at Austin. Bureau of Economic Geology
The Oligocene-Miocene fluvial uranium host aquifers of the South Texas uranium province were deposited principally as syndepositionally oxidized sands and muds. Early intrusion of reactive sulfide- enriched waters produced large intrastratal islands of epigenetic sulfidic alteration, which contain isotopically heavy pyrite exhibiting unique replacement textures. The only known reservoir containing such sulfidic waters is the deeply buried Mesozoic carbonate section beneath the thick, geopressured Tertiary basin fill. Thermobaric waters were expulsed upward along major fault zones into shallow aquifers in response to a pressure head generated by compaction and dehydration in the abyssal ground-water regime. Vertical migration of gaseous hydrogen sulfide was less important. Repeated flushing of the shallow aquifers by oxidizing meteoric waters containing anomalous amounts of uranium, selenium, and molybdenum alternating with sulfidic thermobaric waters caused cyclic precipitation and oxidation of iron disulfide. Uranium deposits formed along hydrologically active oxidation interfaces separating epigenetic sulfidic and epigenetic oxidation zones. Multiple epigenetic events are recorded in imperfectly superimposed, multiple mineralization fronts, in regional and local geometric relations between different alteration zones, and in the bulk matrix geochemistry and mineralogy of alteration zones. The dynamic mineralization model described in this report may reflect processes active in many large, depositionally active basins.
Geologic map of the North Grape Creek quadrangle, Blanco and Gillespie Counties, Texas
(University of Texas at Austin. Bureau of Economic Geology, 1952) Barnes, Virgil E. (Virgil Everett), 1903-1998
North Grape Creek quadrangle is south of the Llano region and is mostly in the broad Pedernales River basin. A few outliers of the Edwards Plateau are present in the western part of the quadrangle. The geology of the North Grape Creek quadrangle is shown on a planimetric map, and the only topographic map available is the reconnaissance 30-minute Fredericksburg quadrangle. Elevations ranging between 1,294 and 1,775 feet were determined during traversing for control, but neither the highest nor the lowest elevation was reached. However, it is estimated that the relief within the quadrangle is about 640 feet, ranging between about 1,200 and 1,840 feet in elevation. The quadrangle is entirely within the Pedernales River drainage basin and is mostly drained by North Grape Creek and its tributaries, some of which are White Oak Creek, Basin Spring Hollow, Dry Hollow, and Smith Spring Branch. The southern part of the quadrangle is drained by Pedernales River and its branches, some of which are Iron Rock Creek and Rocky Creek. North Grape Creek quadrangle is high on the southeastern side of the Llano uplift, and rocks from pre-Cambrian to Ordovician in age outcrop in about three-quarters of the quadrangle. Faults related to the Ouachita orogeny trend mostly northeast-southwest; some trend east-west. The Cretaceous rocks are essentially horizontal, dipping eastward perhaps about 10 feet per mile. Broader discussions of the stratigraphic, structural, economic, and geophysical problems of the region cannot be given in the space available. References cited below deal with some of the problems. This publication on the North Grape Creek quadrangle is one of a series of similar publications, an index to which is shown on the opposite page. The reader is referred to this index map to locate other quadrangles mentioned in the present text.
Ouachita facies in central Texas
(University of Texas at Austin. Bureau of Economic Geology, 1948) Barnes, Virgil E. (Virgil Everett), 1903-1998
Steeply dipping shales and interbedded sandstones presumably of the Ouachita facies have been discovered along the Colorado River in Burnet and Travis counties, Texas. Previously the Ouachita facies was known in Texas only from bore-hole samples. The outcropping rocks are not metamorphosed, whereas many of the borehole samples described in the literature are metamorphosed. A re-examination shows that the bore-hole samples nearest the outcrop lack metamorphism, except for slight changes along slickensides, whereas away from the outcrop the rocks are progressively more metamorphosed, until in Caldwell County, the farthest point reached, the rocks are schist. Lithologies and grade of metamorphism suggest that the Caldwell County bore holes enter the Ouachita facies rather than rocks of pre-Cambrian age.
Phosphorite in eastern Llano uplift of central Texas
(University of Texas at Austin. Bureau of Economic Geology, 1954) Barnes, Virgil E. (Virgil Everett), 1903-1998
A deposit of phosphorite, estimated to be 11 feet thick, was found March 26, 1952, while the writer was mapping ancient sink fillings and collapse structures within the outcrop area of the Honeycut formation south of Marble Falls, Texas. The phosphorite is exposed in a road material pit on the eastern side of a Carboniferous outlier. It rests on shale typical of that in the Barnett formation of Mississippian age and is beneath spiculitic limestone at the base of the Pennsylvanian Marble Falls limestone. Geiger counter measurements, both in the road material pit and on the opposite side of the hill at the same stratigraphic level, gave values of about 100 counts per minute, the background count being about 40 per minute. Another outlier about 500 feet to the northeast possibly contains a similar sequence. Limestone of the type found in the phosphorite in the road material pit occurs as float about this outlier indicating that the interbedded phosphorite may also be present. A Geiger counter examination failed to reveal any abnormal readings, but the phosphorite may be present and masked by soil. These outliers probably are in structural sinks because evidence of collapse is well displayed in the road material pit where both the Honeycut and Barnett formations dip steeply inward. The position of the phosphorite suggests that in age it is between the Barnett formation and the Marble Falls limestone. From stratigraphic position alone it could be a unit of the Barnett formation not hitherto recognized or a basal unit of the Marble Falls limestone. However, conodonts from a limestone bed in the phosphorite and from phosphorite adhering to the bed have been identified by Dr. W. H. Hass of the United States Geological Survey as predominantly Lower Pennsylvanian in age, thus eliminating the possibility that the phosphorite is a member of the Barnett formation.
Review of the geology of Texas
(University of Texas at Austin, 1919) Udden, Johan August, 1859-1932
San Andres carbonates in the Texas Panhandle : sedimentation and diagenesis associated with magnesium-calcium-chloride brines
(University of Texas at Austin. Bureau of Economic Geology, 1982) Bein, Amos
The San Andres evaporitic sequence in the Palo Duro Basin comprises several thick carbonate units in its lower part and many thin units in its upperpart. To the south, across the Northern Shelf of the Midland Basin, evaporites pinch out and carbonates predominate. Six lithofacies were differentiated in the Palo Duro and Northern Shelf carbonates: dolomudstone, pellet-oolite packstone-grainstone, filamentous (Girvanella-like) grainstone, sponge spicule packstone, wispy-laminated crinoid packstone, and skeletal packstone-grainstone. Facies distribution was controlled by water-body salinity, which increased from south to north. Within the Palo Duro Basin, the carbonates in the upper part of the sequence differ from those in the lower part in that the former lack skeletal lithofacies and have higher manganese, iron, and terrestrial organic matter content. Bromide (Br) content in halite in the lower part of the sequence is consistently high, whereas halite in the upper part is mostly depleted in bromide. Strontium (Sr) in dolomite, calcite and anhydrite, ?18O, ?I3C values, and early diagenetic oxidizing conditions deduced from high pristane/phytane ratios are about the same throughout the entire San Andres Formation in the Palo Duro Basin. Depleted ?I3 values in dolomites associated with low pristine/phytane ratios in the Northern Shelf formed under more reducing conditions in which organically derived carbon in the carbonates increased because of sulfate-reducing bacterial activity. Sodium/chloride and potassium/chloride ratios attributed to liquid inclusions in almost all carbonates are characteristic of marine brines evaporated beyond the level of halite saturation. Sodium content in the dolomite lattice is generally low and increases from north to south at the same stratigraphic levels. Varied sedimentologic and geochemical properties of the rocks throughout the area reflect different primary depositional regimes. Properties that do not vary are attributed to diagenetic modification of the rocks in contact with brines having similar compositions. The lower part of the formation was deposited in a broad shelf basin or lagoon sufficiently deep to maintain long periods of steady-state circulation. During these periods neither halite dissolution nor potash-magnesia mineral precipitation occurred. The upper part of the formation was deposited in smaller water bodies sensitive to inflow fluctuations. Increased proportion of meteoric water in the depositional environment during this period is evidenced by high content of manganese, iron, and terrestrial organic matter, and the meteoric water was a source of dissolved carbonate for the deposition of many of the thin carbonate units. Diagenesis of the San Andres carbonates occurred in contact with saline magnesium-calcium-chloride brines, which evolved from seawater by anhydrite and halite precipitation. Skeletal mold formation and subsequent anhydrite cementation, dolomitization, and high-strontium calcite cementation associated with celestite precipitation are all cogenetic processes controlled by this brine-rock interaction. The ?18O composition of dolomite, calcite, and chert indicates apparent equilibrium relations with the same solution. Possible low temperatures of 40 to 450 C (105 to 110 F) imply ?18O of such a solution to be about 2 to 3.The somewhat light ?18O composition of the proposed halite-saturated brine may have resulted from the reversal in the positive correlation between ?18O and increased evaporation in highly saline brines. San Andres carbonates in the Palo Duro Basin that were diagenetically altered in a halite-saturated magnesium-calcium chloride brine were plugged by precipitating salt and remain unchanged and isolated in a closed sedimentary basin. The Northern Shelf carbonates were modified by similar brines intermittently undersaturated with respect to halite because of mixing with seawater. As a result, some original porosity remained, and pressure solution occurred in the more deeply buried and more skeletal-rich sequence.
Sedimentology of the outer Texas coast
(1953-01) Blankenship, William Dave; Damon, Henry Gordon
The Recent as represented on the Texas coast may be separated chronologically into the Ingleside, Alazan, and Post-Alazan or Present times. Each subdivision is associated with a major climatic fluctuation, the Ingleside and Post-Alazan with the “first and second climate optimums”, respectively, and the Alazan with the “Little Ice Age”. Characteristic of the Ingleside and Present times, and possibly of Alazan time, are the associated coastal barrier and lagoon systems. The physiographic features of the Present coastal barrier system forming the outer Texas coast, manifest a direct relation to the climatic characteristics of the Present, favoring onshore movement of sediments. The sediments carried by mainland streams to the bay systems, then moved through the barrier passes by tidal currents, and contributed to a southwestward moving longshore current. Wave transport and eddy action transfer the sediments to an inshore drift current, which is reversible in direction with the longshore component of the local wind. The direction of the inshore drift current affects directly the orientation of foreshore features: spits, bays between cusps, and the associated backwash channels and ripple marks. Three basic profiles representing calm, normal, and storm wind conditions result from secretion or removal of beach sediments. Hurricanes, occurring at any one locality on the Texas coast about once every 25 years, produce great waves that flood the barrier system in the region where the storm track crosses the coastline. A hurricane flood flattens low foredunes, breaks through gaps in higher foredunes, forms washover fans and temporary passes, and carries the material across the island channels, depositing the sediments in front of back dune fields and in the lagoon. The dry portion of the present wind regime (that free of precipitation) transports the Gulf beach sands inland over the barrier system. Precipitation, occurring more often with northerly winds than with southerly winds, reduces the effect of the former on sand movement. SE is the prevailing wind direction and also the resultant effective direction causing Aeolian movement of sand over the barrier system, producing an over-all resultant NW movement. Blowout tongues, barchans, and seif dunes of the barrier system, also the dune fields and wind-cut ridges and furrows of the mainland, have developed trends in agreement with the NW direction of Aeolian sand movement. The NW trends are superimposed on a sand sheet that centers at 27°N latitude on the mainland and extends W from Laguna Madre. The sand sheet was probably the product of a different wind regime because of its non-agreement with the present direction of sand movement. A gradual change of physiographic features southwestward along the coast is the direct result of the different degrees of sand movement corresponding with a climatic range from humid in the vicinity of Sabine Pass to semi-arid on northern Padre Island. Desert-type dunes, the seifs and barchans typical of the great ergs of the world, are found in the semi-arid portion of the Texas barrier system. Of the entire continental shores of the United States, only along the Texas shores do such dunes develop for no other shore in the United States approaches the same degree of aridity.
Studies of Cenozoic geology along eastern margin of Texas High Plains, Armstrong to Howard Counties
(University of Texas at Austin. Bureau of Economic Geology, 1957) Frye, John Chapman, 1912-
The eastern margin of the High Plains in central western Texas affords particularly good opportunity for study of late Cenozoic geology. The topography of the area is dominated by the southernmost segment of the late Tertiary mantle of fluvial sediments, isolated from the central and northern High Plains by the valley of the Canadian River. The eastern escarpment presents many exposures and the canyons that extend into the plains contain, in addition, a nearly complete sequence of Pleistocene terraces and deposits. The Canadian River, which crosses the Texas Panhandle north of the area under study, flows by way of the Arkansas River to the Mississippi. However, in the Plains to the south are the headwaters of drainage to Red River (which enters the Mississippi just above its delta) and of the Brazos and the Colorado rivers, each of which takes its independent course to the Gulf of Mexico. Therefore, the Pleistocene histories of adjacent High Plains canyons are indicative of independent drainage systems. These geographic relationships that place nearby streams under control of three different base level situations give special significance to late Cenozoic correlations in this region. Field work on which this report is based has been discontinuously distributed over a decade. Several short periods were spent in the field from 1945 through 1949 when work was directed primarily toward correlation of Kansan age deposits with deposits in the northern Great Plains and with the glacial section of the Mid-West. This study was carried on largely by use of the distinctive petrography of the Pearlette volcanic ash bed and by fossil molluscan faunas (Frye, Swineford, and Leonard, 1948), but was accompanied by a reconnaissance of Pliocene and Pleistocene stratigraphy of the region. Field work directed specifically toward the present report consisted of several weeks in the fall of 1954 and summers of 1955 and 1956 under the auspices of the Bureau of EconomicGeology of The University of Texas. It is our purpose here to present the results of the regional integrated attack on the problems of correlation by use of fossil molluscan faunas, fossil seed floras, physiographic history, buried soils, lithology, and previously described volcanic ash petrography. From this approach there has emerged the basis for a framework of stratigraphic classification consistent with other parts of the Great Plains region. The data used are relatively widely spaced along the eastern margin of the Plains, and further detailed work is needed in this region to produce a desirable degree of refinement and certainty.
Subsurface Woodford black shale, West Texas and southeast New Mexico
(University of Texas at Austin. Bureau of Economic Geology, 1950) Ellison, Samuel P., 1914-
The geographic distribution, lithology, thickness, and paleontology of the subsurface Woodford in the Permian basin are described and illustrated. On the basis of conodonts and spores, the Woodford is assigned to the Upper Devonian and correlated with the Ready Pay member of the Percha shale in New Mexico, Woodford and Chattanooga of Oklahoma, Kansas, and Arkansas, and tentatively correlated with the Upper Devonian parts of the Caballos novaculite and Arkansas novaculite of Texas and Arkansas. The lithology and paleontology suggest a stagnant marine environment such as might be found in a partly enclosed arm of the sea. The postulated limits of this sea are outlined.
The Midway group of Texas ; including a chapter on the coral fauna by T. Wayland Vaughan and Willis Parkison Popenoe
(University of Texas at Austin, 1933) Gardner, Julia Anna, b. 1882