V fl •..TTJC ,..nT"")T 
.... 8 IS AN O!\IGINAL ···•··· ,\ .:i ,_.J. l
TH L v··r q•·:TOU'T
lTQT n1;' r-1-..~.1.· IED I.L. J.ll
IT MAY j\. .1.J:.:.1 '"'v 
THE AUTHOR'S PERMISSION 


ut~~r, 192s , ~~yr,
~~r0//?i 
_ 
Y.<.t:u 

~2 f, 171-3 


J·:J. <J?~ 

THTS IS Aii ORIGINAL MA-:.TUSCIUPT 
I rn l1't'' ,..)~' -:7 r0·,T::i.J·· r·-:-ri·~~OUT
.l "-•·,. -JI\ J.. .i....1.:,J ~ -...• 4 ..t......... yJ -'• ... ~..,. 

THE AUTHOR'S PEH.MISSION 
SOME CONCRETION-LIKE FORMS OF THE WILLBERNS FORMATIO.N 

OF MASOlJ COUNTY, TEXAS 
THESIS 

Presented to the Faculty of the Graduate School of 
The University of Texas in Partial Fulfill­
ment of the Requirements 

For the Degree of 
MASTER OF ARTS 
By 
Arthur Harwood Deen 
Austin. Texas 
August, 1923 

230785 

SO.ME CONCRETION-LIKE FORMS OF THE WILLBERNS FORMATION 
OF MASON COUNTY, TEXAS 

ACKNOWLEDGMENTS 
I wish to express my indebtedness to those who have assisted in the preparation of this paper. Dr. 
H. P. Bybee, of the University of Texas, has at all times assisted and has given me information and valuable sug­gestions. Mr. L. T. Barrow, a student of the University of Texas, has shown much interest in this problem. He has given valuable information in the taking of the Will­berns section, has assisted me in the collection of samples and in other ways. I also wish to express my thanks to Dr. J. w. Beede and Dr. J. A. Udden, both of the Bureau of Economic Geology and Technology, University of Texas, for the loan of literature that was otherWise, at the time, unavailable. I wish to express my apprec iation for aid given by Mr. Ross Priddy, Mr. R. L. Cannon, Miss Nina Stehr, Miss Elsie Trenckman, and Mr. A. L. Foster. 
Arthur Deen. 
Austin, Texas. August, 1923. 
FIGURES AND DIAGRAMS 

Fig. 1.  C.oncretions  on  the Llano River.  
Pig. 2.  Generalized columnar section tor the Llano-Burnet  
Quadrangles.  
Fig. 3.  Small concretions  on  the Llano River.  
Fig. 4.  Small concretions  on  the Llano Rive1.,.  
Fig. 5.  Diagre.mme.tic cross-section ·or a  concretion <:  
natural size), showing the layers and relative  
thicknesses.  

Fig. 6. Small concretions standing above the limestone, 
on which they have been deposited. 
Flg. 7. A large concretion on the Llano River. 
Fig. 8. Concretions on the James River. 
Pig. 9. Gross-section showing the structure of a large 
concretion on Mill Creek. Fig. 10. Cross-section showing the structure of a large concretion on the Llano River. Fig. 11. Showing structure or a large concretion at the mouth or Mill Creek. 
Fig. 12. c·oncret1on on the James River showing exfolia.tion. 
Fig. 13. Showing strata making the initial bend over the largest of the Mason County concretions. Fig. 14. James River concretion and the rock deformation due to growth. 
Fig. 15. Several closely associated concretions on 
James River resenbling a reef. Fig. 16. Showing the structure of an algal deposit. Fig. 17. Showing the structure of a crypto.z.oon deposit. 
CONTENTS 
PAGE Introduction •••••••••••••••••••••••••••••••••••••••••• 1 Character and Description of the Willberns Formation •• 2 Generalized Columnar Section For Llano and Burnet 
Counties •••••••••••••••••••••••••••••••••••••• 4 Typical Section ot the Willberns Formation •••••••••••• 6 Section or the Willberns Formation Taken Along the 
Llano River ••••••••••••••••••••••••••••••••••• 8 Character of the Rocks in Mason County: Structure ••••• 11 History of the Willberns Formation As Revealed By 
Its Sediments 13 Geographical Location 14 Stratigraphical Location •••••••••••••••••••••••••••••• 19 Concretions in General 20 
Composition. 
Location. 
Size. 
Table or Chemical Reactions Producing 
Concretions. Description of the Mason County Concretions ••••••••••• 30 Size •••••••••••••••••••••••••••••••••••••••••• 31 Shape • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 32 
PAGE Structure • • • • • • • • • • • • • • •• • • • • • • • • • • • • • • • • • • 35 c·omposition •••••••••••••••••••••••••••••••• 41 Number •••••••••••.••••••••••••••••••••••••• 42 Theories of Growth· •••••••••••••···················· 45 ~:irculation of Underground Water • • • • • • • • • • • • • • • • • • • 45 Precipitation of Mineral Matter from Solutions ••••• 47 Discussion of the Theories Concerning Concretionary Growth • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 51 Organic Theory ••••••••••••••••••••••••••••• 51 Stalactitic Theory ••••••••••••••••••••••••• 56 Ascending Thermal Water Theory ••••••••••••• 59 Theory of Descending Water Through crapillary Openings ••••••••••••••••••••••••• 63 Problems of Growth and Accompanying Phenomena • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 64 Capillary Openings ••••••••••••••••••••••••• 64 Beginning of the Concretion •••••••••••••••• 66 Chemical Change Near the Concretion •••••••• 66 Effects of Humic Acids ••••••••••••••••••••• 67 Crystallization •••••••••••••••••••••••••.•• 67 Composition of the Concretion •••••••••••••• 69 Source of Concretionary Material ••••••••••• 69 Water Bearing Ellenburger Limestone •••••••• 70 
viii 
PAGE G~ological Efrects • • • • • • • • • • • • • • • • • • • • • 70 Descriptive Surmnary •••••••••••••••••••• 72 Summary and Conclusions • • • • • • • • • • • • • • • • 73 Bibliography••••••••••················· 74 
INTRODUCTION 
In the summer of 1919, Dr. H. P. Bybee, of the Uni varsity of Texas, who was conducting a course in field geology, with his students, discovered the peculiar rock masses which are to be described in this paper. The follow­ing year it was suggested by Dr. Bybee, and manbers of the Geological Staff, that I investigate this subject. While determining the probably origin of the concretion-masses many problems were encountered. Very little has been written on the subject of concretionary growth and effects o'f organisms on rock fomation, the material available being usually speculative and theoretical. In literature, concretions are frequently mentioned, but as to their origin end growth nothing is said. There are reasons for this. Until the shape, size, structure, and cause for the pecu­liar behavior of atoms and molecules have been dete:nnined, the method of concretionary growth will always be a matter of speculation or conjecture. Again, some of the literature in English, German, and French was not available. There are several problems accompanying the growth of au.ch rock 
masses that, at the present time, are necessarily difficult 
to explain. 
In this paper are given sections and descri.pti ons of ·the Willberns formation, and other facts aboi1t the region which a.re important in that the:y show the conditions surrounding the growth of the cone re ti onary ma.sses and throw some light on the mode of their formation. There follows a discussion of the problems acco~panying growth, the theories of formation, and other points of interest, whereby one may obtain a fairl.y clear idea about the genesis of these forms. 
Character and Descril'tion of the Will berns Formatior1: The Willberns formation which varies from one hundred and fifty feet to approximately four hundred feet in thickness, may be divided into two parts, an upper and a lower, be­cause of differences in composition, color, and texture. Practically all of the formation is thinly bedded more or less lami.nated material. The lower portion of the fonna­tion, which comprises slightly less than two-thirds of the whole, cor~i sts of thin beds of fla,ggy limestone, mea­suring from two inches to twenty inc£es in thickness. These calcareous ·beds are often arenaceous; in fact, a large part of the lower portion contains sandy ircnurities. Glauconi te is another impurity chs.racteristic of this fonnation. This mineral is so abundant in certain beds that it imparts a very dark green color to them. The unner 
bd 
.... 

Q 
•
.... 

• 




portion of the formation differs from the lower portion in that it is made up principally of shale. Above the 
shale, however, there are massive strata of limestone, which will measure from one to five feet in thickness. 
Interstratified with the shale, and only in the shale, are many conglomerate lentils. These measure from a fraction of an inch to fifteen inches in thickness. Lentils of the conglomerate have been noticed, which, within a distance of twenty feet dONn the dip of the rock, whould decrease in thickness from fifteen inches to a fraction of an inch or even pinch out entirely. As in­dicated in the description given by Mr. Sidney Paige, of the Llano-Burnet Quadrangles, the conglomerate lentils are of two kinds. On the one hand, there are lentils composed entirely of pebbles of argillaceous limestone, which show no indication of having been transported by water, or hav­ing been altered by other agencies of erosion. This would indicate that the material composing these layers was de­posited in situ or was carried only a very short distance, while on the other hand the second class of conglomerate 
pebbles strata is composed of rounded limestone~ usually more 
argillaceous than the above,, embedded in a calcareous 
cement, which is usually more or less oolitic. 
Section or the Willberns formation on the east bank of Colorado River, one-third of a mile above the old Tan­yard crossing, 20 miles northwest of Burnet, and 6 miles due north of the eastern corner of the Llano-San Saba County line. (Taken from the Llano-Burnet Folio by Sidney Paige). 
28 27 26 25 24 23 22 21  Top at base of Ellenburger limestone Ft. Impure mottled-brown bedded limestone 15 Ledge of impure limestone 5 Shaly limestone 20 Heavy-bedded limestone, containing abun­dant and exceedingly small shell frag­ments and minute globular remains 10 Impure sandy limestone, having con­glomeratic aspect in the hard layers,shaly material predominant 10 Debris-covered slope 10 Debris-covered slope, contains layersof a shale conglomerate composed of cemented flat fragments of thin shale accompanied by layers containing bowld­er-like forms composed of a lime sand 60 Dark reddish-brown semi-crystalline lime­stone  In. 6  
20 19 18 17  Slope in which occur impure limestone layers breaking down to t inch to 1 inch in thickness, carrying very fine sand, weathering light brown Predominantly pink flaggy semi­crystalline limestone Predominantly pink flaggy semi-crystalline limestone on a gentle slope Almost white crystalline limestone; carries impurities; a few scatteringgrains of glauconite; makes broad  30 5 5  
bench  5  
16  Light-brown crystalline and semi­crystaline heavy-bedded limestone weathering into hard layers; a few scattered grains of glauconite and  
15 14  shell fragmentsCrystalline and semi-crystalline bedded limestone weathering into hard layers Light-brown crystalline and semi­crystalline limestone weathering into beds 6 to 8 inches thick  5 5 6  
13  Heavy layer of light-brown limestone mottled with impurities  4  

12 Alternating beds of crystalline limestone 4 inches to 1 foot thick, slightly more sandy, the whole carrying finely disseminated glauconite 
11 Medium hard layer of sandy limestone carrying glauconite 10 Soft layer9 Hard layer of crystalline limestone 
carrying abundant glauconite grains 
8 Hard and crinkly-bedded limestone 
7 Layers of hard limestone 
6 Gray and greenish-tinged hard flaggy 

crystalline limestone 
5 Layer weathering to a crinkly form, with disseminated glauconite grains; rock of greenish tinge
4 Gray and green hard flaggy crystalline 
limestone 
3 Layer weathering to a crinkled surface 
2 Hard layer of gray and green-tinged

flaggy crystalline limestone 1 Greenish flaggy crinkly limestone, with disseminated glauconite grains. 
Total 
Ft. 
10 1 
1 
2 
1 
1 1 1 1 
In. 

4 4 
8 6 9 
6 
4 
4 
208 3 

The base of the foregoing section is probably about 
30 feet above the top of the Cap Mountain formation. 

Section of the Willberns formation on the south bank of the Llano River about one-fourth of a mile (1350 feet) below the concrete-slab-crossing on the Mill Creek Road, Mason County, Texas. 
Erosional surface Ft. In. 65 Flaggy limestone, §ray with glauconiteand brown sand, variegated" 10-30 
64 . Gray, white and yellow shale, part con­glomeratic, part sandy, part calcareous enormous concretions in the upper por­tion 80 
63 Alternating beds of variegated brown and 
green sandy shale with layer of con­
glomerate 74 62 Hard gray limestone, with glauconite and 
brown sand, middle layer somewhat flaggy 1 61 G~een impure shale 2 6 60 Hard gray limestone, with glauconite and 
brown sand, slightly fossiliferous 1 59 Hard gray limestone, conglomerate circled with brown sandstone 1 58 Hard gray limestone, with glauconite and brown sand 6 57 Same as member No. 62, except only trace · of brown sand 2 56 Impure flaggy limestone, gray with some 
glauconite 8 55 Dark gray limestone, with glauconite 6 54 Green sandy shale; upper part impure, with 
oval-shaped gray limestone concretions 
(which disturb the shale) from 5" to 12" 
to 21x41 in size 4 53 Light gray limestone, with glauconitegrains and brown sandy splotches, con­taining trilobites 1 8 
52 Hard compact crystalline limestone, green­ish 1 51 Mottled brown hard limestone, trace of glauconite 6 50 Hard gray crystalline limestone with 
glauconite 6 
Covered 2 8 49 Hard glauconitic gray limestone, with 
some brown splotches 1 48 Conglomerate 3 47 Light gray limestone. compact, with some 
sandstone l 
Ft.  In.  
46 45  Light gray limestone, compact, less sand White limestone with many brown sand­ 1  
44  stone splotches Hard, dark gray limestone, with few brown  3  
43 42 41  sandstone splotches Hard crystalline limestone, grading from green to red in color Glauconitic limestone with splotches of light brown sandstone Glauconitic sandstone  5 1 4  5  
40 39 38  Gray and glauconitic sandstone Hard pink limestone, glauconitic and crystalline Glauconitic sandstone  1  5 3  
3? 36 35 34 33 32 31 30 29 28  Brown mottled, glauconitic limestone with fossil fragments Slightly flaggy gray limestone, glauconitic part sandy, fossiliferous 3 Glauconitic sandy limestone 1 Light gray limestone with round shot-like particles or brown sandstone Hard light gray glauconitic limestone Hard semi-crystalline, gray limestone Banded glauconitic calcareous sandstone 1 Glauconitie limestone, very little sand, light gray 2 Glauconitic limestone, grayish tinge, slightly fossiliferous, with seam of rotten glauconitic limestone Glauconitic sandstone, then semi-crystal­line limestone, and then sandstone again, some calcite. A thin bed of folded lime­ 5 8 6 3 8 8 8  
27 26 25 24  stone that weathers pink Impure glaucon1t1c sandstone, becomes purethen calcareous, then pure and then cal­careous again Light brown or gray limestone Dark crystalline limestone, fossiliferous, and calcite grains Glauconitic sandstone and sandy limestone, alternating beds 2 to 18 inches thick  3 3 1 3  6 6  
23  Glauconitic sandstone with limestone  
streaks  3  
22  Glauconitic impure sandstone  6  
21  Glaueonitic sandstone, with bands of  
limestone  6  

Ft. In. 20 Gray limestone, glauconitic grains seen as light to dark green specks 6 19 Alternating layers of £ossilif'e1lous lime­
stone and impure greenish sandstone 5 6 18 Impure green shale 1 17 Grayish limestone, with glauconitic se.nd 
and grains or iron 1 16 Glauconitic sandstone, calcareous 3 15 Crumby limestone, pink, with some glauconite 3 14 Glauconitic sandstone, weathering in pockets, 
alternating beds of limestone and impuresandstone 2 6 13 Dark gray crystalline limestone, upper half 
fossiliferous 6 12 Sandy shale, glauconitic 5 11 Dark gray crystalline limestone, very little 
glauconite, fossiliferous 3 
10 Light gray limestone, lower one-third glauconitic, but glauconite disappearstowards top, brown stains 1 1 
9 Grayish limestone, glauconite sand, lower 
half sandy, resembles member No. 8 some­what 2 

8 Grayish limestone, glauconitic sand, not flaggy 2 8 7 Grayish limestone, glauconitic sand, brown streaks,foss111ferous 5 
6 G~ayish limestone, glauconitic sand more 
plentiful than in member No. 5, lower 
part flaggy 3 

5 arayish limestone, glauconitic sand, 
fossiliferous 1 

4 Light gray limestone, glauconitic gr·ains, brown sand traces, with brachiopods and trilobite fragments 6 
3 Grayish .limestone, slightly sandy, glauco­nite grains, brachiopods and trilobites 6 
2 Grayisb limestone, traces or brown sand, con­
siderable glauconite, one layer with tri­lobite fragments 3 

1 Pinkish, crystalline limest one, little gla.u­
conite and some crinoid stems 

Total 286 
Character of the Rocks: The Central Mineral Region is located in the Central portion of Texas, in Llano and Burnet Counties and parts of the adjoining Counties. This area offers to the geologist a place of great inter­est because of the vast number of common and rare minerals, as well as the oldest rocks, and many very interesting problie:ms accompanying them because of igneous activity, metamorphism, unconfonnities, and faulting. The Pre-Cam-. brian rocks of this region are highly metamorphosed, the metamorphism causing the formation of the Valley Springs Gneiss and the Packsaddle Schist. These gneisses were apparently derived from the granitic rocks·, whereas the schists were formed from sedimentary rocks. The Pack­saddle Schist is characterized by marble layers, slightly less metamorphosed limestone, graphitic schists, and rocks carrying iron. 
Between these Algonkian rocks and the Paleozoic formations, there is a profound uncorrformity which caused the absence of the Lower and Middle Cambrian Series. Other periods of erosion took place during the Paleozoic Era, causing the absence, if they were ever deposited, of the Silurian, Devonian, and the Lower Carboniferous, or :Miss­issippian. Again, between the time of the deposition of the Pennsylvanian and the Lower Cretaceous there occurred another erosional period as indicated in the generalized 
12 

columnar-section of the Llano-Burnet region, figure 2, 
page 4. 
The Paleozoic System is characterized by considerable folding and faulting which seems_to have been pre-Cretace­ous in age. Surrounding the Central Mineral Region are found undisturbed Cretaceous beds, whereas the Carbonif­erous rocks that are present are faulted. There are hun­dreds of faults in the area, having a throw or vertical displacement ranging from a few f~et to 1500 feet, or more. As a rule, the faults have a northeasterly or northwesterly trend. 
In the immediate vieinity of the concretions no igne­ous of metamorphic rocks are exposed at the surface. All members of the Upper Cambrian are present in the immediate area. with the exception of the Hickory sandstone. This formation, however, can be found to the east of the area shown on the map indicating the location of the concretions. Comanchean rocks are found in the Blue Mountains ten miles to the west and in the low hills to the south. 
Several very interesting examples of Paleozoic fault­ing can be seen in this region. In passing down the road leading to the Mill Creek Ranch owned by a Mr. White, a fault can be seen fifty feet west of the gate at a distance of three and seven-tenths miles from the town of Mason. 
Upon passing down into the valley in the direction of the Llano River, this fault line is clearly visible for several miles. On the Carboniferous rocks the vegetation is rank, dense, and dark green, whereas on the other side of the fault line, on the Willberns and Ellenburger limestones, there is scarcely any vegetation. In the summer of 1919, the writer surveyed this fault block, and found that it varied in width from a quarter of a mile to one and a quar­ter miles. Its length is approximately seven and one-fourth miles. Other similar fault blocks can be found in this region. 
From a study of the sections of the Willberns, given above, it is possible to draw some conclusions concerning the conditions under which the formation was laid down. This formation and the Ellenburger are interesting, since the Willberns contains the concretions; and, as the writer will try to show, the Ellenburger was the probable source of concretionary material. Previous to the deposition of the Willberns formation, all indications point to the fact that there was an uplift causing the deposition of a sandy stratum, which is persistent over practically the entire area. At the beginning of the period there occurred an extensive submergence of the land, thereby creating the conditions necessary for the deposition of limestone. Dur­ing the entire time of depos:ition in this period, however, 
230785 

14 

the sea was not very deep, as indicated by the glauconite deposit and by the nature of the Willberns itself. The very thin beds of shale, the conglomerate lentils, and even the sun cracks all point to the fact that the area was not covered continuously with water. In other words, the argillaceous and arenaceous deposits indicate that the re­gion was a mud flat, now and then covered by water, due possibly to the rise and fall of the tides. Near the top of the section of the Willberns taken in Mason County, there are massive layers of limestone. This fact again signifies another land movement. These limestone layers, containing a very small amount of glauconite and some sand, would suggest that the waters were as yet not extremely deep. But, in the Ellenburger, the lowermost portion being extremely arenaceous, one concludes that the the sea covered the land to a considerable depth. Practically the entire thickness of the Ellenburger, except the sandy layer men­tioned above, is unusually pure limestone, being 59% calcium carbonate. 
Geographical Location. Mason, the County-seat of Mason County, Texas, is situated 32 miles west of Llano and about 138 miles slightly northwest of Austin, Texas. To reach the particular locality containing the concretions to be described, it is necessary to travel the Mill Creek road a distance of ten miles in a southwesterly direction from Mason. As the concretions are found only in the Will­berns, it is not necessary to search for them in any other locality in the vicinity of Mason. There are rmny places in the Willberns where these rock masses are exposed as indicated on the map, page 18, but there are several expo­sures that can be more easily studied than others. The first area marked "A" on the map is about 1800 feet down the Llano River from the Mill ·creek Road crossing, 30 feet above low water level; a second exposure is in the bed of a dry arroyo between this location and the high cliff above 
the mouth of Mill Creek. It is about 1000 feet up stream 
on the east bank, near the ordinary water level and is marked "D". A fifth place of interest marked "E" is found on the west bank of the James River, another tributary of the Llano, four miles from the mouth of the stream. Again, on the Llano River at a point marked "F" there are several extremely large concretionary masses. At several points both along the James and Llano rivers there are concretions that hav'e weathered out of the rocks holding them. They are at the present time resting just under the cliff or near the river 's edge. 



Fig. 5. 	Diagrammatic cross-section of a concre­tion (~ natural size) showing the layers and their relative thicknesses. 

Fig. 6. 	Small concretions standing above the limestone on which they have been deposited. 

I ) 


Stratigraphical Loe a tion. The upper one-third of the Willberns fonnation consists of shale and flaggy lime­stone With more massive and thicker layers of limestone towards the top. At the several points noted above, it is very difficult to detennine whether the concretionary masses are all in the same horizon or not. At first sight it seems that there is evidence that the concretions found at the location "A" are not in the same horizon as those found at point "C". After an examination of this partic­ular point it was seen that the beds of rocks at the first­mentioned location apparently dip under those at "C". At point "A" the shaly layers have a dip of 3,0 3·01 to the southeast, while those at the other point dip only i 0 to the southeast. There is a possibility that there is a fault between the two points near the srmll ravine at location "B", but because of the surface erosion and the similarity of the rocks in which the fault seems to occur, it could not be traced out. Considering the above along with the fact that there is no difference lithologically between the two areas, which are only 1000 feet apart, it seems plausible that there is a minor fault and that these concretions lie in the same horizon stratigraphically. (See section page 8, members number 54 and 64.) The other concretions at the other points all seem to occur in the 
same horiz.on except at location "F". With a continuation of the same dip to the southeast as is exemplified in the rocks at location "C", there is no doubt that the concre­tions both along Mill Creek and on the James River are all at the same horizon in the formation stratigraphically. On the Llano River, at the point already mentioned, the con­cret ionary mass seems to be still farther up in the fonnation in the more massive layers of limestone described on page 5. 
Concretions. Concretions are usually nodular, but often irregul.arly shaped masses showing a wid.e variation in size and,having a different composition from the enclosing strata,occur in a very large part of the sedimentary rocks. They are usually deposited around a nucleus through the action of some chemical process at a time subsequent to the deposit ion of the surrounding roci{. Du.e to the fact that thes e bvdles pre.sent such a. variety of forms, compo­sitions and stratigraphic cccurrences, it may be conducive to clearness to discuss, briefl;/, some of the most important examples. Concretions of different cor.1positions are found in sandstones. These are usuall;/ siliceous, but there are instances where the u-.aterial is calcareous. In argillaceous sandstones there are often fcund concretionur:l masses with a greater percer.:.tage of clay than the enclosing material. Some of the best examples of siliceous concretions are 
21 

founa in the States of North and South Dakota. Examples of these calcareous-siliceous concretions are found in Mellette, Todd, Bennet, and Washington Counties. At points 4 miles to the southeast and 3 miles to the south of Williston, North Dakota, on the Missouri River, silice­ous concretions from 8 to 10 feet in. diameter ocaur. Another lo~ality in the immediate vicinity of this place is on White Earth River near the town of White, Square Butte Creek, end Custer Trail Ranch. On Square Butte Creek many of the con­ereti ons measure from 20 to 25 feet in diameter. These 
I 
masses are found in the Laramie Formation, as well as the 
' 
Arikakee, Protoceras, and Oreodon Beds of the Quaternary. The most interesting occurrence of the siliceous concre­tions in this region, however, is at the headwaters of Grand and Morean Rivers in North Dakota. These concretions have often been referred to as the "fossil shores" because 
·their length and curvature resembles the crescentio shape of shore lines. These log-like deposits are composed of sand grains indurated by a calcareous cement. They contain no fossils, but show lamination and ripple marks and occur 
I 
never over 2 rods apart. These "logs" are always broken by joints cBllsing a series of segments to be formed measur­ing from.6 to 160 feet in length and approximately 2 fjet in diameter. Other examples of siliceous concretions may 
22 

be found in the Watkins Glen Q.uadrangle a few miles south of Elmira, New York, in the Chemung Sandstone... Still another instance may be cited, namely, the remarkable siliceous con­cretions on the Isle of Man in the Tertiar:y.,. Fonnation, d.es­cribed by Strickland. As in the above examples, the cement­ing material was calcium carbons.te. These deposits are 
--. always parallel to the planes of stratification, and show a mammillated form. There are clusters of these forms which, in some instances, will weigh several tons. Strick­land describes these deposits as being due to certain cur­rents operating during ebb tides, because in several instances he has found them to have .large pebbles near the end which acted in the same mazmer and served the same purpose as an obstacle in a sand dune area. Many other examples could be cited, but these will suffice to show some of the peculiar­ities of this class. 
Another very common class of concretions is that com­
posed of iron. In clays, sandstones, marls and limestones 
pyrite and mares.site nodules are found. In the vicinity 
of Austin, Texas, the Austin Chalk has these nodular masses 
which, in some localities, change the 1 imestone to a dark 
brown color because of the weathering of the iron. The 
nodules usually have an outer surface that is tuberculate, 
while on the interior a radiate structure is found. Con­
23 

cretions of this character usually do not attain a size over two or three inches in diameter, but there are many exceptions to this. Again, another class of iron concre­tions known as clay-iron-stone, or sphaerosiderite, is very abundant in some of the Carboniferous shales. In certain localities where these masses are very abundant, they have been used as a source of iron ore. Many of these specimens measure as much as three feet in diameter. Usually these clay-iron-stone nodules, as well as the pyrite and marcasite concretions, form around a fossil. Recently the 
_writer examined several of the concretions of this type from the Carboniferous and in almost every case they con­tained several joints of a crinoid stern. Very interesting examples of the iron concretions have been described by O. 
w. Willcox. The concretions that he describes in the Jour­
nal of Geology, 1906, are located at Red Bank, New Jersey, 
in Monmouth County. These tubular masses often attain a 
length of 20 feet and always lie horizontally along the 
strike of the rock. Their distribution is irregular, but 
their effect on topography is somewhat unique, in that they 
form the tops of many of the hills, especially in Monmouth 
County. Willcox concludes that these were formed by diffu­
sion. The iron is obtained from the disseminated glaucon­
i te. Where no concretions are found, the sandstone has a 
dark brown color, but where these tubular masses are abun­
dant, the sand is usually very light or even white. Many 
examples of this type of concretion are found in the United 
States. Other good examples may be found in the bed of 
Grand Lake, Nova Scotia, in Red Crag at Felixstow, Suffolk, 
England, and in the post-Tertiary clays near Gla,sgow. 
Phosphatic concretions are often present in certain limestones, marls, clays and shelly limestones. There are several instances on record where these deposits have been worked as a source of fertilizer. Concretions of this character usually have almost perfectly preserved bones about which the phosphate was deuosited. Although there are examples of phosphate concretions in this country, the best examples are to be found in the Lower Green Sands at Atherfield on the Isle of Wight and near Havre, France. 
Flints and cherts probably should have been mentioned along with the siliceous concretiJns since they are both siliceous in composition. These deposits are nearly always found in limestones. Flint is the common variety of crypto­crystalline quartz and chert is an impure fonn of flint. These occur in the limestones in the form of nodules or in bands which are often made very irregular because of nodular masses of the same material attached to the bands. Cherts and flints due to radiolarians, spic·u.ler:i of sponges, and emsnations from siliceous springs are found in several 
25 

formations and in many localities. The Edwards Limestone of the Comanc'hean near Aus tin, T.exas, and the same forma­tion near Junction, Texas, show excellent examples of this deposit. Other localities may be found in Mono Lake, and off the Florida Coast near St. Augustine. The Radiolarian Cherts of the Franciscan Group are very interesting, and the University of California has issued a bulletin fully describing and giving the origin of these deposits. Another article giving the origin of certain cherts and flints was published by F. M. Van Tuyl in the American Journal of Science, in the year 1918. 
The most interesting concretions because of their size and effects are the calcium carbonate or limestone con­cretions. It is not always true, but usually the case, that calcium carbonate concretions occur either in limestone formations or shales, usually the latter. The bodies are more or less spherical, though often they are flattened and elongated. R. A. Daly has described large calcareous concretions occurring at th~ ena. of Lake Huron in Lambton County, Ontario. The shales in whlch they occur are about the same age as the ~enesee ·of l~ew York, Huron Shale of Ohio, or the "Black Shale" of Michigan. The concretions are, on an average, approximately two feet in diameter, while there are except ions that are even three and one-half feet in diamet·er. These masses containing 88% Caco3 , 
26 

have deformed the shales on all sides of the spheroid, like those that will be described later. Concretions of the same character are found in abund8l1ce in the Els.ck Shales of Ohio and Indiana, in the Chemung, Genesee, and Tully formations. A locality three miles from L1"innea.polis, Ottawa County, Kansas, contains ab out 50 detached specimens 12 t:eet in di amete r. This reg i on has often been c allea "Rock City," both by the residents in the locality and in literature. Other examples of calca.reous concretiJns have recently been discovered by Dr. J. VI. Beede, of the Univ­ersity of Texas, in the Delaware Mountains of Western Texas. The most interesting calcareous concretions are to be found in the Magnesian Limestones of Durham, .E:hglana, and in the Cape Province of Southeni Africa. Mr. E. J. Garwood, in the Geological Magazine for 1891, described the deposits in England, giving some very interesting data c.oncerning their topographic effects and , the possible mode of their formation. Referring again to the Cape Province region, it may be said that these concretions, as described by Dr. C. 
J. Maury, of Corne 11 Uni ve rsi ty, are the la. rge st that have been described to date. The concretion described in the American Journal of Science for 1917, is very unusual in that it is almost pure calcium carbonate. It was deposited in the Malrnesbury Shales, the age of which, as yet·, has not been definitely determined, but it is possibly Cambrian. 
Dr. Maury, in a communication, said that no more details concerning these concretions could be given other than those stated in the American Journal of Science for 1917, because of the fact that Mr. Stephen Dahse, the owner of the quary in which the concretion was found ·, had been killed in a South African campaign, and that she had lost all of her data and. samples of the concretion on her return trip through the South Sea Islands. Dr. Maury, having assisted Professor G. D. Harris on his report, Bulletin Number 7 of the Geological Survey of Louisiana, in which he gives his ingenious theory regarding the formation of salt domes, concludes that the concretion was formed in the same manner as the salt domes of the Gulf Coastal Plain. 
Mr. J. M. Anns Sheldon has described in detail a number of calcareous concretions from the Champlain Clays of the Connecticut Valley. He selected his specimens from several hundred collected from many localities along the valley. His discussion of their formation and the effects of their growth is interesting, in that he brings up some questions that must be explained in finding a cause for the development of these masses. These questions will be taken up later. 
There are many other types of concretions such as the hydraulic limestone concretions of the Lias, the coal balls of the Coal Measures, the acresp ire, and the dolomitic con­
28 

cretions in the magnesian limestones, Imatra stones in the 
marly formations of Finland, the manganese concretions 
on the Pacific Ocean floor, forming at the present time, 
the greensands, the pseudo-coprolites in the Crags of 
England, and the siliceous oolites. 
The following is a table of chemical reactions 
showing how some of the concretions mentioned above are 
formed. (From J. E. Todd: Concretions and their Geolog­
ical Effects. ) 
Solution of -By-Becomes Solid­
co3 Evaporation of co2 CaC03 (Calcite
CaC~ gg3
FeC " " 002 FeC03 (Siderite 
Action of ~s Fes(Pyrite

Fee~ 3
Fee co3 " " c co Fe 6 3H~O (limonite
·Fe2"3
FeC co " " oxyg~n
,,
FeS04 3 Fe " "
" " 
FeS04 " org. weathering FeS2 (Pyrite or marcasite N92 Si03 " Caco3 or Caso4 Si02 ( Q.uartz 
Some concretions are amorphous in form, as, for example the phosphatic masses; others, such as flint, are cryptocrystalline; others consist of crystals in varying sizes, as are found in many calcareous as well as gypsum, pyrite, and marcasite concretions. The fonnation of con­cretions is not closely dependent on any single inorganic substance, or on any one type of crystalline structure. Concretions seem to arise, generally, from the tendency of 
29 
chemical eompounds to be dissolved slowly by interstitial water, either while the deposit is unconsolidated or at. a later time. Certain nuclei, present in the rock, then determine reprecipitation of these particles in solutions, and the deposit once begun goes on until either the supply of material for growth is exhausted, or the ph:;sical char­acter of the bed is changed b~l nressure and conso1i dation until conditions are no longer favorable to further accre­tion. In the ma,jority of cases it is not the crystallizing force alone that attracts the particles. The structure of flint shows that the material has so little tendency to crystallize that it remains pennanently in a cryptocrys­talline state. That the concretions grow in consolidated sediment in a solid state is proved ·by the manner in which the bedding 'planes pass through and around them. This is shovim in many calcareous and siliceous concretions. That the sediment was soft may be shown by the purity and perfect form of the crystals in some of these. The crystals must push aside the matrix while they are forming. Probably decomposing organic matter supplies substances for the growth of nodules, acting partly as reducing agents, or otherwise detennining mineral precipitation in those places 
where organic remains are mingled with the sediments. 
Description of the Mason County Concretions. 
Size. The concretions range in size from those that are corrmonly seen as one, two, or three inches in diameter, to those which are as much as two hundred feet in diameter. The writer has found none described in literature that in any way approaches the magnitude of these masses except the pure limestone concretion described by Dr. c. J. Maury. The size of this concretion in the Cape Province has not been definitely detennined, but is approximately 70 feet thick and 200 feet in diameter. There is only one in the area under consideration that reaches the extreme size mentioned above. There are many concretions, however, that are as IIlllCh as 25 to 40 feet in diameter. 
!t .Bll
In the bed of the ravine nt locat:..on indicated on the map, page 18, are hundreds of the small concretions. The sizes range from a quarter of an inch to eight or ten inches in diameter. To show the abundance Of these bodies the following figures will be given. In a rectangle 10" by 22" there were 27 small concretions from one-half inch to two inches in size. In another place 22" by 22" there were 76 of these concretionacy bodies. To make a good comparison, they had the appearance of biscuits in a pan. They are usually arranged extremely close together, often merging, though ordinarily more than half an inch a1:s.'rt. At and near location "D" on Mill Creek small co ncre tions are plent i:ful. Here these deposits are better exposed and 
31 

are aeoessible and easy to s tu. dy. 
In the cliff thirty feet above low water level at 
point "A" can be seen concretions of greater size than the 
above. There is no o~her place where they are as well 
preserved and so well exposed. The shale surrounding them has been weathered and transported down stream leaving them more or less protected by the overhanging cliff of massive 
and more resistant limestone. The following figµres will give the exact dimensions of a number of concretions at this point: 
1. 
7 feet long, 5 feet wide, and 3t feet thick. 

2. 
5t feet long, 4 feet wide, and 2 feet thick. 

3. 
5i feet long, 4 feet wide, and 2t feet thick. 

4. 
5t feet long, 5 feet wide, and 2t feet thick. 

5. 
6 feet long, 4t feet wide, and 2t feet thick. 

6. 
6t feet long, 6 feet wide, and 2~ feet thick. 


7. 7 feet long, 4 feet wide, and 2t feet thick. The above concretions are all to be found within a radius of seventy-five feet. At this same place can be seen fifteen or twenty smaller concretions rarging in size from four to eight inches in diameter. On Mill Creek at location "D" there are other excellent examples of concretions of this size •. 
Along the Llano River at the various points indicated on the map, page 18, are fine specimens of the larger concre­tions measuring 20, 30 and even 40 feet in dianeter. They oan best be seen from the north side of the river, since they are located in an overhanging cliff over one hundred feet in height. Those embedded in the cliff are inaccessible, but 
32 
some have been weathered out and are immediately under the cliff or in the stream. Figure 7 shows one of the concre­tions which measures 65 feet in length and 30 feet in height. At a point farther down the same river is t;i.not her locality at which may be seen concretions of this magnitude. The most gigantic of all the concretions was found on the Janes River four miles from the mouth of the stream. It measures 250 feet across, and its height was estimated at 75 feet, neither the top nor the bottom being visible. Figure 13 shows the strata making the initial bend over this huge mass. In this same region there is, a very interesting group of concretions. There are a number of these bodies that have grown together as shown in figure 15. At first sight the group has the ~pearance of a reef. 
Shape. The shaue o'f concretions has been variously desert bed by the use of the following terIIE; spherical, cyl­indrical, elliptical,nodular, ellips6idal, fusiform, botry­oidal, mammillated, tube rculate, lenti. cular, approaching the oblate spheroid, glorular, flatten ova:ls and spheroidal. As to the shape of the masses under consideration, no one of the above terIIE will accurately describe them all. The concretions first herein desert bed, or the srm.ller ones, are always rounded on the top, though very irreguJar. What might be tenned the polar diameter is in every instance much 
33 

less thin the equatorial diameter. In other words, the thickness is less than the diameter. Again, briefly refer­ring to the larger concretions the dimensions of Which were given on page 31, it can readily be seen that these bodies have a spheroidal and, at the same ti.me, an ellipsoidal or elongated form. Some of these masses could better be des­ert bed as approaching an extremely flatten obla. te spheriod. The majority of the concretions with sizes of those referred to above are flattened and in several instances almost per­fectly flat, due probably to weathering. Sneller concretions may be found that will be two or three times as thick as the width, causing them to have a cylindrical form. All of the concretionary bodies of the greatest magnitud.e have a flat­tened spheroidal form. There are, however, variations in the degree of flattening. Several of them along the Llano River as well as on the James River have an almost spherical shape. Figure 4, on page 16, indicates this very clearly. 
Some explanatior: of the manner in which these con­cretions are placed in or on the surrounding rock wi 11 be given here, since this has oometh ing to do wi.th the form of the deposits. As previously stated, these bodies are in every instance, with the exception of 1h e one place on the Llano River, deposi tea. on a more or less massive layer of limestone from three to six or more inches in thickness, 
Fig. 7. A large concretion on the Llano River. 

Fig. 8. Concretion on the James River. (Noticethe arching o:f the shaly limestone above.) 
35 
and are surrounded or covered by shale or shaly limestone. Due to the f ·act that the 1 imestone which acted as a floor or base far the beginning of these bodies was resistant, and still underlain by more resistant 1 imestone, the bottom of the concretions are flat like the layer of stone on which they were deposited. This lower port ion is always irregular, being pitted with indentations due probably to the minor irregularities in the limestone or to the effects of the pressure on the limest.one caused by the force exerted during crystallization and deposition. 
The flattened co ndi tion on the top of the concretions, as described above, is undoubtedly due to the pressu·re of the overlying rock. It can readily be seen that the great thick­ness of the superincumbent rmss would exert enough pressure to change the form of a more or leas unoonsolidated body as well as to cause the point of deposit ion or precipitation to migrate. 
Structure. A partial description of the structure of concretionary mass es was given above in the general consider­ation. The exceedingly large concretions of calcium carbon­ate, as well as others, often have a concentric struc1:ure. Concretionary masses formed because of the action of algae and hydroid polyps will show a concentric struc1u re in the case of the first mentioned, and a banded and hummocky appear­ance in the case of the latter. There is of course a point 
of beginning which is often a fossil. Fossils, both plant and animal, have been found in numerous concretions of various compositions and sizes. There are, however, meny instances where the center was not a fas sil. The writer has examined several fl int and chert specimens from several localities, more especially from the Ellenburger Limestone of Mason County, that have very small siliceous pebbles as nuclei. The nucleus may or may not be present. Prof. R. Blum, in the Neues Jahrbuch fttr Mineralogie, for 1868, has classified concretions, placing them in four groups. His first class is the closed concretion, that is, those masses \\hich have lost their attracting cent er, or nucleus, because of a chemical reaction. This change was effected by the water which brought in the concretio nary substance. The second class may be called the nucleus concretions and their centers may be either organic or inor­ganic. A third class is the septaria, due to d1'{ing, with which we are familiar. Lastly, there are the hollow concre­tions, due (1) to contraction, (2) to chemical change of the interior w.i. thin the concretions, or (3) to the disappearance of the once present nucleus, caused by chemical action of percolating water. Examples have been found where only a part o:f the nucleus rermined. 
Interruptions in deposition is the principal cause 
37 

for concentric strucinre. One ]ayer of material will be 
deposited, then precipitation may tenporarily cease or per­
haps may be only slightly decreased in accordance with the 
amount of water coming in contact with the concretio nary 
mass. Successive accretion of layers give the older ones 
more time to harden, c au.sing the interior to be much harder 
than the exterior. Mr. W. Spring, in his original article 
"On the Influence of Time on the Hardening of Pressed Chalk" 
in the Zeitschrift fttr Inorganische Chanie, for 1896, and 
summari.z e d in the Neues Jahrbuch, for 1897, gives :facts 
regarding the hardening of chalk that muld be interesting 
when considering the concentric stmcture of concretions and the hardness of the interior. Dry pulverized chalk was 
placed in screw press under as great pressure as possible for a period of seventeen years. The material was very notice­ably changed during this time. Its hardness had changed 
until it had become conchoidal in f .racture, ancl it resembled, to a marked degree, lithographic limestone. Likewise in 
any concretion, es:pecially those under consideration, where there was a great pressure exerted by the superi~umbent 
layers of limestone, there was undoubtedly a great change 
brought about in the texture, thereby possibly changing the 
structure of the whole, ··as was the case in Mr. Spring' s 
38 

experiment. 
Small concretions found at the locality rm rke d "B", as well as at the point called "D" on Mill Creek, resemble in appearance, at first sight, the Paleozoic stromatopora reefs which were so abundant and attained a diameter of 10 feet. The concretions in Mason County, whEn carefully studied microscopically, do not show the definite structure found only in deposits af organic origin. The srrall concretions, as described on page 30, when viewed in a body give a hum­mocky appearance as in the stromatoporoid masses, but they are not joined at their bases, forming below a number of bands placed successively on each other. These deposits, however, are all separate and distinct from each other, each one acting as a separate point of deposition for con­cretiona:cy material. As shown in the diagram, page 17, these small masses have a form somewhat conical in shape, or, in fact, a cone-in-cone-structure. According to Prof. R. Blum, in the Neues Jahrbuch f'ttr Mineralog ie, page 296, 1868, concentric structure is caused by irregular rates of deposi­tion; therefore we can infer that for a comparatively long time the rate of depooition was fairly constant, and then there occurred for a very short period of time a cessation of deposition. These small bodies usu.ally have from three 
39 

to five distinct layers varying in thickness according to the size of the mass. These conical layers are very thick at the apex of the cone as compared with the thickness near the base. The bases of all the small concretions are more or less flattened and having been deposited, in the beginning it seems, on a slight irregularity of the limestone stratum holding them. 
So far, there has been found no evidence of a nuclear body, which may have acted as a center of deposition. Accord­ing to Prof. R. Blum, these would be classes as closed con­cretions. There has been no cavity or trace of fossils found in any specimen examined from Mason County. 
Larger concretions, as found at the location indicated on the map as "A", show no such structure as described above. The masses at this point were described on page 31, and it is seen that these are a hundred times as large as those ,at "B". Each mass seems to have been a single point of deposi~ tion, which makes it markedly different from the larger con­cretions to be described later. It appears as if these masses, in three instances, at least, showed very crudely a layered effect that might be interpreted as a concentric structure; but because of the fact that practically all of them did not show this characteristic, it seemed almost eonclusive that these examples, which were always exposed to the elements, 
whereas the others not, were simply examples of exfoliation. 
It was impossible to examine the interior of these large masses in search for a nucleus, since they doubtless weigh many tons. 
The largest concretions found in the Mason region are composed of a large number of smaller concretions, usually neither more than ten inches in diameter, nor less than six . Figures 9 and 11 will show this very clearly. The points of deposition were, without doubt, similar to the small concre­tians described on page 30. Because of increased growth these bodies grew together, so to speak, forming the whole number into one huge body, giving it the appearance figured above. Two of the concretions that have fallen from the limestone bluff show that the srrB 11 concretions are several feet in length and nearly circular, but resembling columns of solidi:f ied basalt. In the majority of accessible con­cretions this is not shovm because, undoubtedly, the pressure caused from the overlying rock, and the lateral pr essure exerted by the growing concretion have caused a fusion or welding of these smaller masses into a large one as in the case of the chalk, when placed under great pressure by Mr. 
~ 
.
..,pring. Compoo iti on. A qualitative analysis of the concre­tions was made, as well as a quantitative analysis for the 
41 

anmnt of calcium carbonate. Several samples from the con-ere tions at the different · local it ie s were analyzed by the 
"Tolumetric method" for the detennination o:r calcium carbonate. Also, several sanplea of the Ellenburger 1 imestone, the forma­tion '· above the Will berns, was quantitatively analyzed for cal­cium ca·rbonate, simply for comparison with the conaretionary 
material.  The  c  oncretions contain iron, potassium,  silica,  
.,.  
magnesium,  aluminium, and  a  high percent of calcium oxide.  

Disseminated throughout the concretion is a m"ineral known as glauconite, which is a Silicate of iron, al.uminium, and po­tassium. The magnesium is present, which must, according to some scientists, be present before concretions will fonn. Silica occurs combined with the iron am potassium and as uncombined quartz. Possibly it was gathered from both the Ellenburger and Willberns. Some of the concretions have a larger amount of aluminium than others, and it is this element, according to Dr. E. P." Schoch, of the University o~ Texas, that prevented the crystallization of the calcium carbonate. 
The percent of calcium carbonate varied from 63. 2% to 74.31%. The average anount of calcium carbonate, however, was 72.66% for the twenty sanples analyzed. The srmllest amount of calcium carbonate was obtained from the concre­tions on the Llano River, ·found at location "C", on the map, page 18 · , and the amount was 63. 2%. The amount of 
42 

calcium carbonate in the Ellenburger limestones averaged 69.68%. Comparing the average amounts of calcium carbonate o-:f the Ellenburger limestone and the concretions it is seen that the concretions have from 5% to 15% more calcium car­bonate, than the Ellenburger limestone, from which the writer thinks the concretiona:cy rm.teri.al was derived. 
Number af the Concretions. As indicated on the loca­tion map, page 17, there are six important localities that are accessible for study, besides many other localities. In many of the small arroyos and on the sides O·f many hills one can recognize these bodies, though they are indistinct. Often there will be only a few square feet af the concretion appearing at the surface with the peculiar structure as shown in Fig. 9, which is co nc lusi ve evidence of a concre­tiona:ey-body. Nearly all of these that are found on the sides of' the hills and in the ravine bottoms have ring& of yellow iron stain. These rings are present around the small concre­tions which, in 1urn, constitute the larger concretion. 
At localities "B" · and "D" the concretions are most abundant, in fact there are hundreds of them to be seen. There can be found as many as 75 in an area less than two feet square. The larger concretions measuring two to seven feet in diameter are. very scarce, only one place sh Olli ng than exposed at the present time. 
Fig. 9. 	Cross section showing structure of a large concretion l~ miles up Mill Creek from the mouth. 
Fig. 10. 	Cross section of a large number of small concretions on the Llano River below the concrete sJab. 
Fig. 11. Showing the structure of a large 
concretion at the mouth of Mill 
Creek. 
The largest concretions, namely, thooe that are almost wholly visible, are also few in number, totaling not more 
than 25. 
Since these masses are found at so many points over the Willberns area, undoubtedly, many of the concretions have been destroyed, whereas others are covered by the Willberns and Ellenburger 1 imestones, and these eventually will be exposed if the present conditions continue to exist. 
45 

THIDRIES OF OONCRETIONARY GRCWTH 
Concretions compJ.ring in nature to those described are thought to be formed by thermal waters coming from below, by circulating ground water go.ing from the surface downward, or because -0f the presence of certain organisms. A concretion formed according to the second process may be developed as a stalactitic mass in a previously formed cavity, or it may originate subsequent to the rock strata in which it is found, thereby deforming the strata above end possibly below. Before beginning a discussion of the above theories, it. is necessary to inquire into the facts about the circulation of underground waters and causes for precipitation. 
According to observations, free water is found in even the most impervious rocks. Fresh granites and basalts will absorb water in small quantities. Agates and cha.le edony, when boiled in staining solutions, wi11 absorb so me of the stain through the sn:all sub-capillary openings. Van Hise states in his Treatise on Metamorphism that fresh granites will contain from 0.20% to 0.50% pqre s~ce, compict lime­stone 2.5% to 12.5%; sandstone from 5% to 28%; and clays and loams slightly higher than sandstones. Consequently the anou.nt of water that will penetrate these rocks and 
46 

circulate will vary considerably. The amount of water flovv ing through. rocks depends on the continuity, the forces producing circulation, and the size and number of the pores. Following Van Hise, o:r.;enings in the rocks are 
(1) those which have a length much greater than their width, (2) those whose cross sections are essentially the same, (3) and those irreguJar in nature. Openings of the first· division are bedding planes, ,joints, faults, fissures, and fissi lity .i oints, while those of the second class are the voids found between the grains or }llrticles making up limestone, sandstone, or conglomerate. The first mentioned openings are most common in sedimentary rocks, and those of the third division are most pro rninen t in igneous and me tamor­phic rocks. Lavas and scoriaceous rocks have irregular pores or cells which are formed by steam and other gases, and are therefore more or 1 ess discontinuous. 
The size of the openings is ve-:ry important in the rate of circulation of ground water. Since the amount of pore space and size of openings are not alwa:YS the same, it may be we11 t o re fer to the siz e o f o re ning s mor e in detail, because a rock with a few., but large, pores under the same conditi ons as one with rmny snall spaces will permit a vastly different amou~nt of water to permeate and 
flow. Van Hise' s classification of openings on the basis o-f sise, is a follows: (1) Openings larger than those of ospilla:ey size, or super-capillary 0µ3nings--0.508 mm. in diameter, (2) capillary openings--0.508 to 0.0002 mm. in cliemeter, (3) openings srmller than those of capillary aise, or sub-capillary openings--0.0002 to 0.0001 mm. in diameter. Super-capilla:ey openings will for ordi nary pur­poses include those openings given under (1), page 46, and will also iml ude those spaces in very coarse corglomerates and sanclato;nes. The capillary_ openings through which most of the water movanent takes place are fcnnd in shales, limestones, and slates. In the sub-capillar.v openings the attraction o-.f the solid molecules extends from wall to wall, and f orim a film within the pore. 
It is only necessary merely to rren ti on t l:e factors influencing the mot ion of underground water. These forees, on the one hand, are gravity, heat, mechanical action, molecular attraction, and vegetation, while on the other hand the oppooing force is internal. friction. 
Having discussed very briefly the circulation of underground water it is necessary to give the pri r.ci p:Ll causes for the precipitation of mineral matter from solu­tions. Super-saturation is the only necessary condition 
48 

for precipitation, and this is brought about in various ways, of thich the following are the most important: 
(1) 
by a change of pressure, ( 2) by a change in temper­ature, (3) by evaporation, (4) by reactions between aqueous solutions, (5) by reaction between aqueous solutions and gases, (6} by reactions between solutions and solids, 

(7) 
by electricity, and (8) by organic processes. 


Where the total volume of the solution is more than the first volume of the solvent and the substance dissolved, an increase of pressure causes precipitation, due to the fact that the volume of the solution has been lessened, thereby decreasing the "holding" power. On the contrary, when the total volume of the oolution is less than the first volume of the solvent and the substance dissolved, a decrease in pressure will cause precipitation. 
It is usually true th2t an increase in tempera­ture for mo 2.t solutions up to certain points causes an increase in the:Lr solubilities. Therefore a decrease in temperature gives the proper conaition--super-saturation-­for prec ip i tation. Ascending water will be rising, usual l~ u:na.er the proper conditions, since there is a comparatively constant decrease in temperature a,s the surface is reached. 
On the contrary, descending waters will be influenced by warmer temperatures, thereby increasing the solubility, and these waters on their return upward. will be ca.IB ble of depaa i ting some of the mate rial held in solution when the lower temperatures are reached. 
Salt deposited from so·lut ion, bees.use of evapora­tion, is the best example of this process. The amount of water is decreased by evaporation, consequently de­oreas~ng the volume of the solvent and at the same time leaving the salt. 
When any combination of the various ions in a solu.tion can fonn to a sufficient extent with ions of another solution so that the newly combined ions are insoluble in the liquid present, they will be precip­itated. Many examples of reactions of this nature are made use of commercially in the chemical laboratory. 
Another instance of the formation of insoluble ions is often brought about by the introduction of a gas into a liquid solution. The most important example of this kind of reaction is the mixing of oxygen with a solution of iron prot oxide. In qual­itative analysis hydirogen sylphi de is us:ed to precipitate 
mineral s: ubs tances held in sol:ition. 
The most common as well as the most interesting reaction between solutions and solids which causes pre­cipitation is the dolomitization of limestones. The reaction that takes place is the exchange of ions. The magnesium carbonate held in solution when in con­tact w.i th the solid caJ.c ium carbonate will exchange ions, forming magnesium c.arbonate by the addition of co2from the limestone. It will cause the formation of limestone, or calcite, by the addition of the CO · from the mag­
2 nesium carbonate. Again, there is possibly a reaction between the ions of Ca and Mg, or one will replace the other. Several French scientists have experimented with electricity as the pre('.ipitating agent in solu­tions. Becquerel and Thenard, as well as English sc ie nti sts, have worked along this 1 ine. There is at the present time, however, very little lrnown about the process. They give a long list of tests making use of electricity, and the results of their work can be found in early numbers of Comptes Rendus . 
After stating the theories regaxding ooncretion­ary formation, and considering very briefly some facts concerning the movanents of circulating water and precipitation except the last mentioned cause for precipitation, which will be referred to later, the theories of concretionary growth may be discussed, the last mentioned being taken first. 
Recently there have been several articles writ­ten about the effects o,f plant and animal life on rock formation. After reviewing the available literature on the subject, reading espec i.ally Pre-Cambrian and Carboniferous Algal ~eposits by w. H. Twenhofel, and Pre-Cambrian Algonkian Algal Flora by c. D. Wolcott, and seeing the similarity between the deposits they described and those under consideration, the writer saw the possibility that these were farmed through the action of animal, or plant life. The method by which the precipitation of calcium carbonate is brought about because of the presence of algae is by the absorption of the carbon dioxide in the water, and the release of oxygen to the surrounding water. 
These two changes in the content of the water bring about a decrease in the capacity for the water to hold the calciun1 carbonate in solution. It is then precipitated about the bases of the algae and upon their thalli. The chemical aquation showing this reaction is as follows: 
CaH(co)0 Ho Cacoco0
232 23 2 
W. Ketchell in the First Annual Report af the Geolggdeal Survey of New Jersey; w. s. Blatchley and G. H. Ashley in their report on the Lakes of Indiana, 1900; c. H. Davis in the Geological Survey of Michigan,. 1903; B. M. Davis in Science, July 189'7, and many others have des­cribed in detail numerous deposits and have given the possible effects of the plants and animals on the accu­mulation of the rock masses. 
The most conclusive evidence of the formation of concretiona:ry masses through the agency of algae, or other plant, or animal life, would be to find the process taking place; this has been done in many places. The structure of these bodies has been examined and described. The concentric structure in deposits of this nature, as well as in some concretions, is due to 
53 

interruptions in the rate of deposition. Algae which are essentially thermophilous plants are either killed or greatly retarded in growth during the winter months. At the beginning of spring they again begin to grow and multiply in great numbers, and within several months they are exceedingly numerous. This seasonal growth in numbers v.ould cause a period of rapid pre­cipitation, or deposition. The concentric laminae are nearly always the same thickness and more or less porous. The calcareous material· in these masses will be dissolved when treated with acids leaving a mat of vegetable chains and cells. 
Upon examination, it is readily seen that there is a similarity between figures 6, 9, 10 and 11, and figure 
17. The cross sections shown in figures 9, 10 and 11 are not so distinct as they might have been, due to the fact that the rock mass was covered with fungi. Some few concretions show several thin layers of material and figure 12, showing a James River concretion, dis­tinctly shows the layers of the mass. This peculiar characteristic is indicative of either algal of cryptozoon deposits. At locality "A" on the map, page lffi, there are approximately 25 of the small concretions from four 
54 

to twelve inches in diameter, which protrude :from three to ten inches above the rock in which they are nset." Passi'Ql y they have not been exposed very long to the action of the weathering agencies, but 8-re so much more resistBn t than the Willberns limes tone that they protrude a·bove the rock. These concretions are very close tcgether as shown in :figure 5, and there is no doubt but th& t these concre­tions, i:f weathered of'1· on a level with the stratum hold­ing them, would appear similar to the rock masses repre­sented in figures 6, 9, 10 and 11. 
The srre. lles t concretions hs,d what might be called a conical structure. The concretions under consideration must, if formed by the action of algae, possess the con­centric structure, as shown in figure 16, or that as shown in figure 17, if :fonn ea b:y crypto.zoon. None of the concretions in I:Iason County have a true concentric structure. The· layers or what seemed to be layers on the concretion, especiall~1 those in !figure 12, were eight­een inches in thickness, while those sbo\•vn on other con­cretions were much less, ubually only one-eight of an inch in thickness. Only three large concretions were found on which this characteristic was not iced. It is not possible for algae to cause the formation of suoh 
thick separable layers, but as has been suggested, 
these are undoubtedly instances of exfoliation. 

Since these concretions, because of their presence, have caused a disturbance of the shaly limestone, both above and below them, how could this be explained in the light of the algal c1eposi t theory? First, to have th~se masses formed by the action of algae or oryptozoon, these deposits must have been formed while the Willberns was being deposited. Due to the fact that this f orma tion, at the horizon where the concretions are found, was an off shore deposit, these large bodies would have been deposited in an exceedingly short time. Suppose these deposits had been formed at a period of slight or no deposition of the Willberns. A further and later depo­sition of the shaly material would possibly, -through sagging, cause the layers to bend over the rrasses as 
.shown in figure 4, but it seems more plausible that if these were reefs, and they were formed as supposed, the layers of later deposition would grade into these or come to an end at the very edge of the mass. 
A thorough microscqµ,c examination of one hundred thin rock sections of the concretions revealed no evidences of organic origin. The rock specimen when treated with 
acids will not leave any trace of chains of cells, as were found by H. Justin Rhoddy, (American Association for Advancement of Science Publication, 1897), and 
others in their study of deposits of this nature. The porous nature of the layers formed by algae and related plants and some animals was not observed in these con­
cretions. 
The conclusion reached, after studying these deposits, taking advantage of the work that has been done on this subject, was that these remarkable deposits were not formed because of the presence or action of any organisms, either plant or animal. 
There have been found concretionar.v masses that were undoubtedly due to deposits that are vers clos,ely related to stalactiti·tee, or deposits that were made when water dropped from the top of the cavity in the rock. E. J. Gar­wood in the Geological Magazine, for October, 1891, gives_ some of the characteristics of deposits of this nB,ture, when showing that the concretions found at Marsden :~~uarry on the coast of Durham, near Sunderland, are not related to the stalactitic deposits. The beds in which the deposit of calcium carbonate is formed, would be obliterated, leaving an irregular ca vity. Another fefj,ture characteristic of such deposits would be the absence of lines of stratification 
57 

Fig. 12. 	Concretion on the James River :four miles from the point where it enters the Llano River. 
Fig. 13. 	Strata IIlRking its i nit iaJ. b End over a big concretion on the James River four miles from the moo th. 
through the matrix and the concretion alike. Masses of this nature, unlike concretions, would not contain fossils.· Still another feature of such deposits would be the lack of definite structure. When the masses were very small there would possibly be a structure such as is usually found in stalactites, but in masses measuring several feet in diameter there would probably be no definite structure, since several points of dep<Eition would be necessary to form such large masses. 
The small concretions in Mason County resemble stalactitic deposits in part, but two important character­istics are la.eking, and this alone is enough to give ab­solute evidence that they are not such deposits. Concre­tions from one-half to three inches in diameter seldom fail to show a structure that would possibly indicate such 
a.n origin or would lead one to investigate their formation in the light of this theory. In the description above, it was stated that these masses compared favorably with the cone-in-cone structure. The layers of the cones because of their thickness would indicate a period of constant precipitation and then a very short cessation in deposition. As stated previously there is no trace 
of my orgs,nism in any of the concretions. These two facts would perhaps indicate a stalactitic origin. In none of the concretions do we find stratification planes, but the layers of limestone JS.SS above or below the mass without a ·break in continuity. There is one example in which the 1 imestone appears to have been eroded before the deposition of the concretion, but this apparent contact line between limestone and the concretion might be due t 0 the covering of travertine and moss. All of the masses are more or less symmet­rical in form, being approximately spherical, there being· no evidence of erosion in the farm of a cavity antedating the precipitation of the calcium carbonate. These facts would lead us then to investigate other methods of formation. 
Another theory for the formation o:f ooncretions may be called the ascending thermal water tm ory. The writer has found only one instance where this has been suggested and it is in the article in the American Journal of Science, Volume 44, 1917, writ ten by Dr. C. J. Maury. She states that it is her opinion that this enor""". mous concretion was formed in the same manner as salt dome deposits on the Texas and Louisiana Coasts. 
Fig. 14. 	A concretion on the James River, ahONing the bending o:f the shaly limestone, the nature of the laminated material, and the peculiar spher­ical weathering. (Four miles from the mouth of the river.) 
Fig. 15. 	Several closely associated concretions on the James River. (Notice the dip of the roe k.) Four miles from the mouth of the river. 
There is evidence that the numerous domes on the Gulf Coastal Plain are founa on lines of structural wealmess. It is supposed that thermal waters penetrated these fissures, and because of the decrease in te mpera­ture and lessening of pressure, the salt was precipi­tated. The fissures never reached the surface or were covered ·by later sedimentary deposits. Due to the crys­tallization of the salt, the strata above were domed, giving rise to the structures, in which oil has accumulated. Mr. 
E. T. Long has published several experiments in the Ameri­can Joumal of Science, for 1917, in which he states that saturated hot brines will deposit salt when cooled, and that the developing crystals will exert a lateral pressure sufficient to permit continued growth even in the presence of opposing forces. Another interesting piece of work has been done by Mr. Stephen Taber on the grow th o:f crystals, and his work also has been published. in the American Journal 
o:f Science, for 1916. It has been stated tmt the pressure exerted by the growing salt crystaJ.s Will be approximately the amount of the crushing strength. Blocks of ordinary rock salt that have been exposed to the air for a consider­able length of time have ·been tested in the Bureau of Econ­omic Geology, University of Texas, and revealed a crp.shing strength often as much as 40,000 pounds :per square inch. 
1
It seems plausible that 1n the interior, or deep down in the earth, where there are no atmospheric agencies to affect the salt, that the crystals would exert much more pressure than given in the fjgure above. This pr es sure would un­doubtedly be SU:fficient to disturb the overlying strata. Immediately beneath the Willbe rm f'orma tion, in which the concretions are found, is the Cap Mountain Limestone; below· this the Hickory Sandstone; and then the AJ.gonkian or Precambrian series known in the area as the Packsaddle Schist and Valley Springs Gneiss. The Hickory Sandstone is from 0 to 200 feet thick, the Cap Mountain usually less than 90 feet, and the Willberns 250 feet crr more. The Hickory Sandstone has a very ~igh percentage of iron; in fact, the rock is extremely dark red in color, and at times is almost black. It seerrs that,if the concretions under co nsideration were farmed in the same manner as the salt domes and the water came · through them, they would contain a large percentage of iron. In fact, they contain less than two per cent of iron and this is in the form of a silicate of iron, aluminium and potassium, which is the mineral glauconite •. 
Perhaps the deposits were formed by waters coming from the underlying Cap Mountain. If this were true, there would be evidence be low the oo ncretions of w ch water movements. Several localities are easily accessible 
where the concretions are well exposed, and the strata below the concretions are continuous throughout the whole visible vertical di stance, and there is not a trace of a fissure or minor fault through which water could rise. In fact practically all the concretions· are placed on a mas­sive layer of limesto-ne, and this is in no instance broken by joints, fissures, or minor :faults in the irrunediate vi­cinity of the concretions. 
Fig. 16. 	Depos.it formed by the actions of Blue-green Algae. (Walcott: "Pre­cambrian Algonkian Algal Flora?). 
Since none of the theories already dis cussed account for the deposits under consideration, it is necessary to
• revert to the theory merely mentioned at the beginning of the discussion as an explanation of their probable origin. Percolating water from above entering the capillary open­ings and finding a proper place for deposit ion because of supersaturat.ion, due mo st 1 ikely to a change of pres sure and also to chanical reaction due to the uniting o:f the 
solvent with a previoualy existing substame, is no doubt 
the oause of the concretions. Many quest ions may be asked, 
for example: What force binds the calcium carbonate to­
gether? Whenoe came the calcium carbonate in the concre­
tion? What caused the limestone to be dissolved, and then 
redeposited? What dete :rmines the shape? What causes the particles to be drawn tcgether? Will the material during deposition cause the disturbance of strata found above and 
below the concretions? 
· Solutions of calcium carbonate will penne ate and flow through even the srrs.llest capillary openings and will begin to deposit calcium carbonate under the condition of lessened pressure, as was probably the case w:ten tbe water reached the more or less impervious layer of limestone on which the concretions were deposited. These rmy begin to fonn around a previously existing substance, either a fossil or some of the same material previously held in solution. This nucleus will communicate its conditions to other bodies within its influence, or attract other rarticles, or cause them to be precipitated out of the solution. It can readily be assumed that the percolating water is saturated Wi. th uncombined carbon dioxide which would be derived from the Willberns formation, whic.h is carbonaceous. The calcium oxide comes 
65 

from the calcareous shales and ·the more or less pure Willberns and Ellenburger 1 imestones above. 
Fig. 17. cryptozoon proliferum Hall. (Wale ott: "Precambrian Algonkian Algal Flora.") 
Suppose we were to have a su:e.11 am runt of calcium carbonate either deposited previously or organic in origin. This will detennine a point of deposit ion, si nee it acts as a stimulus to the breaking up of the saturated bicarbonate. The monocarbonate will be deposited around the nucleus, leaving water still charged with carbon dioxide. The mono­carbonate volume with that of the biproduct is gres,ter than that of the original bicarbonate and expansion results. This expansion apparently tends to push the water from the small capillary openings and consequently cause a cessation of growth. But Jamin and others have shown that the re can be an equilibrium between two unequal forces, provided that the liquid in the tube be interrupted by air bubbles. The air bubbles cause attraction, and the same is true for any other insoluble gas or 1 iquid. In the capillary openings there will possibly be hydrocarbons, and their distri bu­tion will excite attraction, causing a differerrt ial pressure within the water, while in equilibrium from without. This would thus cause a pressure between the mass of calcium carbonate and the rock mass surrounding it at all points except the capillary tubes. This force with the help of the expansive energy o:f the freed carbon dioxide tends to deform the rock surrounding the mass. The solid carbonate will keep the decomposition of the bicarbonate in process, 
67 

and as long as the . w.pply is obtainable, the concretion 
should grow. 
The presence of humic acids is very con<hcive to the solut.ion of calcium carbonate. Many aci da are farmed by the decomposition of plant life and these acids in dilute aqueous solution are sufficient in many instances to dis­solve the material and by causes mentioned elsewhere, the material is deposited. The agency that draws the particles together, other than the natural causes of precipitation, is either molecular attraction, chemical affi. ni ty, or electrical energy. The manner in which these agencies operate is imperfectly understood and will continue to be until the size and shape of the molecules, their structure, and inherent energy stored up in these snall particles are thoroughly understood. 
The usual result of precipitation, when there is no in­terference, is the formation of crystals, but when the re is interference, the substance will, nevertheless, cohere. The solvent will ordinarily incorporate some foreign mater­ial upon approaching the point of deposit ion and th is might account for the glauconite disseminated throughout the con­cretionary mass. There is undoubtedly a chemical energy stored up in the molecules of 1 ike substances that causes one to attract the other. Continued molecular attraction impoverishes the surround liquid, causing the f orma tion of 
68 

diffusion currents coming from all directions. This mot ion 
of molecules will not cause a motion of the solvent; but when the liquid is so impoverished that practically all 
the molecules have been precipitated, a dif:fb.sion of liquids which, in this instance, are different in composition will take place, and consequently continue to supply ma­terial for the growth of the concretion. 
Pre.ctic ally all minerals that are soluble may take on concretionary form when the point of saturation is reached through cooling, but only those soluble under ordinary temperatures and other conditions will re:n ain in this form. Foreign substances usu.ally do not hinder the growth of concretions. It seans impossible for an attraction between molecules to exist which would be so strong as to exclude such material as glaoo oni te. The Willberns and the Cap Mountain are cha.racteriz ed by this mineral. Some substances TIBY cause certain minerals not to f onn crystals, but they will not hinder attraction and coherence. 
H. B. Stooks has performed several interesting ex­periments along the 1 ine of concretionary fonnation in the presence of acids and at different temperatures of the solvents. He found that cal.cium carbonate in the presence of organic matter would form in rounded or spher­
69 

oidal masses or crystals, but if' in the presence of organic acids, dumb-bell or imperfect spheroidal shapes were asw.med. These factors will possibly be th~ cause of the spheroidal shape of the mass, but the resistance 
to displacement by the shale, and the rate of supply are th·e most important factors in its determination. The mass will grow outward into the shallow sp:i. ce offered by the outward thrust and this opening though possibly only capillary in size will afford sufficient freedom for the liquid to move over the surface of the deposit and pre­cipitate the material held in solution. This continued growth due to the crystallizing force and energy·coming from the change of volume causes the disturbance o:f the strata both above and below, as shown in several of the figures. 
As stated before, the concretions are composed mostly of limestone. They also contain a srmll amcunt of silica, alumina, potassium, and iron. The silica is in the form of a silicate of potassium, aluminium, and iron or the mineral glauconite, while some is uncombined and is brought in from the arenaceous shales surrounding the ooncretions. The co·ncretionary material is a very hard 1 imest one with a conchoidal fracture resembling the Ellenburger Limestone 
70 

above in color, hardness, fracture, and composition. 
The material in the concretions was without doubt derived 
from the Ellenburger and possibly from the Willberns; 
but due to the fact that the ooncretions and the Ellen­burger are so nearly alike in every respect, it seems more plausible that the concretionary nn terial was nearly a1·1 derived from the water-bearing Ellenburger. Several springs and caves found in the immediate vi.ci ni ty indi­
cate strongly that the water, bearing calcium carbonate, 
came ·from this :formation and later deposited the concre­
tions in the Willbems forim.tion. This seems to be the most plausible origin of the concretions. 
The geological effects of concretions are not nu­merous. In some of the cool beds, are often found con­cretionary masses known as "Coal balls" which are detri­mental in that they have to be separated from the coal, entailing an extra expense. The greatest effects of con­cretions are exemplified in the Dakotas and New Jersey. The sandstone concretions in several localities form a cap to the hills and this has caused a very rugged topogra­phy, approaching, in some instances, the "bad land" type. The small concretions in Mason County have had no material effect on the relief, but the larger concretions have caused a disturbance of the strata that wruld ordinarily 
71 

be unnoticed. The srr.aller concretions, two feet in 
diameter, have caused an upward arch of the shale one ~oot from the normal position. Take, for example, 
those masses as much as twenty feet in diameter, and 
in one instance over two hundred feet long and seventy­five feet high. It can be readily seen that these would C811Se a marked effect on topography. There will not be in any instance the proportional d ifferenee in defonna­tion between the s:rmller and largest rrasses mentioned, but these large dep osi ts have caused small irregular it ie s to be visible at the surface. At one point on the Llano River immediately over a concretion that measures some forty feet in diameter, the rock that had a nonnal dip of four degrees to the southeast now has a dip of 16 degrees to the southwest because of the disturbance due to the grow th of the mass. 
DESCRIPTIVE SUMMARY 

1. 	
Concretions vary in size from one-fourth inch to 250 feet in diameter. 

2. 	
Spheroidal in shape. 

3. 	
Large concretions made up of smaller concretions. 

4. 	
Composition average 72% calcium carbonate, small percentage alumina, iron and silica. 

5. 	
Hardness--3.5 

6. 	
Fracture--Conchoidal. 

7. 	
Tenacity--Brittle and slightly subtranslucent on a thin edge. 


a. 	Color--dark to light gray depending on the amount of alumina. 
9. 	
Texture--Compact. 

10. 	
Small concretions show a cone-within-a-cone structure. 

11. 	
Large concretions do not show a concentric structure. 

12. 	
No trace of organisms in the deposits. 

13. 	
Shale deformed above and below the deposit though not so much below as above. 

14. 	
No nucleus present in any of the concretions. 

15. 	
Analyzed samples of Ellenburger limestone averaged about 59% calcium carbonate. 


73 

SUMMARY AND CONCLUSIONS AS TO ORIGIN 
The concretions herein described were formed not by the presence of any organisms, ascending thennal waters, or stalactitic process, but by circulating water entering and JB.SSing through capillary passages. The force causing the disturbance of the surrounding rock was the expansive force of the monocarbonate when depos­ited from solution. The material was derived from the overlying limestones and was deposited because of chem­ical affinity, molecular attraction, or other causes. 
74 

BIBLIOGRAPHY 
The following references include those given be­low. Other references that have important material bearing on the subject other than a mere mention of location, size, composition, etc., are marked thus (#). 
#American Academy ot Arts and S~1ences. Memoirs, 1883, . . v. 11 , p • 107-134• 
#American As§ociation for the Adv!i11Qeme!t~ ot Science, 1855, . v. 4, P• 12; 1879, v. 28, P• 311-409. 
American GeolQi1st, v. 17, 1896, P• 347; v. 19, 1897, 
P• 324; v. 33, 1904, P• 360. 

American Jo-qrnal of Scienge, Ser. 4, v. 41, 1916, P• 532; 
···· Ser• 4, v. 43, 191'7, p. 28 9 • 

#American Journal pf s91ence. v. 44, 191'7, p. 369-70• 
. Z .. 
#American Journal of Science, v. 58, 1919, p. 132. American Naturalist, v. 17, P• 1267-68. #American Philosophical Society, Proceedings, v. 54, 1915, P• 246-258. #Annals & Magazine of Natural History, v. 6, 1880, p. 384-395, 
p. 34'7-461. Ansted, D. T., An Elementar* Cpurse in Geology, Mineralogy,
and Phys{cal'. QiOgra;p:y, 1s5o, p. 227-202. · Arkansas Geological Survey, v. 2, 1892, P• 108. Bischof, L.ehr:bucn,. Band I, p. 114. 
75 

Bowney, 	T. c., In Darwin's Coral Reefs. Appendix to Third 
Edition, Smith Elder & Company. 

Boston Natural History Society, Proceedings, v. 1, p. 325­331; v. 2, P• 124-130; v. 6, p. 132ff; v. 24, P• 115­140; v. 25, ·p. 115-140; No. 1159, P• 309. 
Bulletin Cambridge Museum of Comparative Zoology, v. 17, 
1889, P• 121-170; v. 26, 1893, p. 1-203. 

eanadian Record ot Science, v. 8, No. 5 1 1889, P• 292. 
Chemical News, v. 40, 1897, P• 103-104. 
Challenger Report, Deep Sea Deposits, 1891. 
Cole, Aids in Practical Geology, P• 209tf. 
Colorado Scientific Society Papers, c:oncretions of Chalce­dony and Opal in Obsidion and Rhyolites of Colorado. 
Colorado Scientific Society Papers, No. 506C, p. 7-9. 
Comptes 	Rendus, v. 70, 1870, p. 1412. 
Connecticut Clays and Clay Industries, Bulletin No. 4, 
P• 27, 32, 34, 35. 

# c:ourty, G., 'A. propos des calcaires magnesiens concretionnes du Compte de Darliam (Grande Bretagne)'; Socie~ Geo!_gg_t.9J1~ ,£~ ~anc.e B.~i:tet~:ri.~ 6. Serie 4, 1906. 
Crosby, 	w. o., Dynamical and Structural Geology, 1892, 
p. 2'70-27 9. 
erosb'y, 	W. O., ''On the Elevated Coral Reefs of Cube..'' Boston ~?~38: lia~.~~!~t.Q:o!: {'rQ9.Q~Q.J,ng.§.. v. 22, 1892, 
Cuvier, 	Rec.~E?r,,£h.f!.~ !g +Et,.! Q11_~,~m~~s" F()~.~,t.;!.,~,,_,~,, 3rd Edit1on,Tome II, Part I, 1828, P• 341. 
Dana, J. D., Manual Q.! q_e~lo~~' 4th Edition, 1896, p. 139. 
Dana, J. D., Manual of Geology, 1st Edition,. 1863,p. 96, 
-~·-...-l"_.,..,.... ·~ -~. 	. .·' 
76 

626-627; 4th Edition, 1895, pp. 96, 97, 139, 140, 274, 493, 603, 605, 666, 677, 688. 
Darwin, Charles, Geological Observations, p. 54, 69, 303. 
Davis, W. M., ''Dana.'as Conformation of Darwin's Theory ot Coral Reefs. Ameri~~n J9~n~l . <?f Science, 4th Series, 
v. 35,p. 173-88, 1913. -	. -·--. 
Dawson, J. w., Acadia~ Geology, p. 76. 
_ ....--..."••-J~· • w~ '• • • '• • • ,' 
Economic Geology, ·v. 5, 1910, pp. 224, 529, 530; v. B, 1913, 
p. 443. 
Pleld 	Columbian Museum Publications or Geological Series, III, No. 3, P• 25-54. 
Geikie, A., Textbook of Ge_qlc:>,gy, 1st Edition, 1882, p. 489; 1893, p:--12·t;~..~I3·~·-; 140-142, 156, 17?, 178; 3rd Edition, 
p. 66, 103, 510, 513, 1053. 
Geologist Association, Proceedings, v. 11, 1889-90, p. 424; 
v. 12, 1891-92, P• 225; v. 14, 1895-96, P• 210; v. 18, 1903-04, p. 137; v. 48, 1892, P• 43-115; v. 58, 1902, P• 46-58. 
Geological Magazine, N. s. Decade iv, v. 3, 18?6, p. 218,220; 
v. 
7, 	1890, P• 79, 117-127; v. 8, 1891; v. 14, 1867, 

p. 
437, 481; v. 15, 1868, P• 12, 156, 208; v. 161 1869, P• 529; v. 17, 1870, P• 10; v. 8, 1891, P• 433­


440. 
Geological Magazine, December, 1906, P• 553. 
Geological Proceedings, v. 4, 1843-45. 
Geological Survey Bulletin, v. 25, No. 1, 1914, p. 77. 
# Geological Survey of Louisiana, Bulletin No. 5, Notes on Geology of Winfield Sheet. 
Geological Survey of Michfgan, Annual Report, 1901. 
Geological society of America, Bulletin 9, 1898, p. 427-428; Bulletin 12, 1901, p. 1318; Bulletin 14, 1903, p. 353­368; Bulletin 18, 1907, p. l-28; Bulletin 24, No. 2, 1913, P• 253. 
77 

Geological Survey of Canada, Annual Report, "''• 2, 1886, 
pp. 18d, 59e, 68e, 73e, 8le, 90e, 9le, 95e, 98e, 
lOOe, 119e, 128e, l30e, 13le, 150e, 133p. 

Geology of Colorado Ore Deposits, v. 1-2, 1888, p. 107. 
Geology of Iowa, v. 1, pt. 1, 1855, pp. 190, 191, 201, 215, 

216, 226, 2'ZT, 236, 242, 243, 254, 255, 275, 276. Geology of Pennsylvania, v. 1, 1858, p. 581. Georgia Geological Survey, Bulletin, No. 18, p. 97, 139, 435. 
#Grabau, A. w., Principles of Stratigraphy, 1913, pp. 718-721, '763-765. Green, A. H., Manual of Geology (3), 1880, p. 2'79-282. #Hunt, T. s., Chemical and Geological Essays, 1878, p. 89. Iowa Academy of Science, Proceedings, v. 1, pt. 4, 1893, p. 55; 
v. 4, 1895, p. 55; v. 10, 1902, P• 103. 
Iowa Geological Survey, Bulletin, v. 11, 1900, p. 16. 
Illinois State Geological Survey, Bulletin 13, p. 17, 71; 

Bulletin 26, PP• 102, 104, 151; Bulletin 27, pp. 33,
120 • . 
Indiana Geological Survey, Memoirs, v. 12. 
Journal American Chemic'J.l Society, v. 27, No. 9, 1905; v. 
62, pt. 2, 1892,p. 1373; v. 15, 1862, p. 107. 

#Journal of Geology, v. 8, 1900, PP• 135-150; v. 14, 19061 
p. 243; v. 20, No. 31 1912, PP• 259-269; v. 26, 1918, PP• 412-438. 
#Julien, 	A. A., On the Geological Action of Humus Acids. American Association for the Advancement of Science, 
v. 28, 1879, P• 311-409. 
Kansas University Geological Survey, v. 1, 1896, p. 88. 

Kansas Academy of Sciences, Transactions, v. 16, 1897, p. 
43ff. 

Le ~onte, Joseph, Elements of Geology, 1886, pp. 188-190; 
1892, PP• 189-190. 

78 

Linck, G., Oolitic Limestones of the Bahamas. 
Linnean Society of London, Transactions, v. 7,pt. 4, Sept.,1906, pp. 45-68. #Llano-Burnet Folio, u. s. G. s., No. 183. Lyell, Sir Charles, Manual of Elementary Geology. Lyell, Elements of Geology, 6th Edition, 1866, p. 37. Lyell, Students Elements C,f Geology, 1871, p. 63-64. Manchester Geological Society, Transactions, v. 1, 1841, 
p. 
80-89; v. 13, 1874, p. 141-148; v. 21, 1892, 

p. 
364-398, 401-422; v. 22, 1894, p. 632-652; v. 25, pt. 16, 1898; v. 28, pt. 14, 1904. 


Massachusetts Geological Survey, Report, 1833, p. 180. 
Memoirs 	of Museum of Comparative Zoology, Harvard College,Reefs, Agassiz, v. 28, 1903; v. 26, 1895. 
Merrill, G. P., Rocks, Rock-Weathering and Soils, P• 32, 
232. 
Meunier, M. S., C·ontribution a l 'Estude des Concretions 
Silicenses, Societe Geologique de France, 
Bulletin 5, Serie r, 1910. 

Meunier, 	M. s., Sur des Concretions quartzenses Reufermees dans la Craile Blanche de Marguy (Oise), Societe Geologique de France, Bulletin 4, Serie 4, 1904. 
Michigan Geological Survey, Report, v. 2, 1873, p. 48, 56, 209; v. 3, 1873-76, P• 64-68; v. 5, 1881-93, pt. at, P• 21. 
Mississippi State Geological Survey Bulletin No. 16, p. 68. Murchison, R. I., Russia and Ural Mountain Geology, v. 1. Natural History of New York, Part 4, P• 82, 125, 409. Nature, July 18, 1918, p. 392; v. 94, P• 477; 1879, v. 18, 
P• 628. 
79 

Neues Jahrbuch fur Mineralogie, 1845, P• 816r; 1849, p. 757b; 1892, P• 266; 1899, P• 385; 1901, P• 351; 1902, P• 399; 1903, p. 374; 1868, p. 294-308; 
1854, P• 367• 
New York Academy of Science, v. 2, P• 48. 
#New York G·eological Survey, Report, 1893, p. 292. 
North Dakota Geological Survey Report, Third Biennial 
Report, 1903-4, p. 65, 167, 168. 

Ohio Geological Survey Bulletin, 4th Ser. No. 17, p. 231. 
Ohio Geological Survey, 1870, p. 276, 290. 
Ohio Geological Survey, Economic Geology, v. 5, p. 268. 
Oklahoma Geological Survey, Bulletin 7, 1911, P• 26-34. 
Page, Textbook of Advanced Geology, 5th Edition, 1872, P• 454. 
' 
Pennsylvania Second Geological Survey, Venango c·ounty 
District. 

PhilosophiC(Jl Transactions of the Geological Society of London, 1797, p. 386; 1798, p. 15; 1822, p. 24, 
27. 
#Philosophical Transactions of Royal Society of London, 
v. 145, 1855, p. 149-156; Series B, 1909, p. 
167. 
Prestwich, Joseph, Geology, 1886, v. 1, p.142. 
Quarterly Journal of the Geological Society of London, 
v. 
13, 1557, P• 363; v. 18, 1862, P• 106-112J 

v. 
32, 18?0, P• 60; v. 36, 1880, P• 1-22, 80; v. 43, 1887, p. 599-604; v. 43, 1887, P• 734-735; v. 44, 1888, p. 371-374; v. 49, 1893, p. 124-128; v. 49, 1893, p. 236-240; v. 53, 1897, p. 479, 511, 

p. 
297-304; v. 58, P• 1902, p. 46-58. 


Report of Superintendent of the Coast, Survey, Florida Reefs, 1851, p. 145-160. 
Report of British Association for the Advancement of Science, 1844, p. 155; 1879, p. 312; 1886, p. 670; 1889, P• 597; 1899, P• 741; 1900, p. 737; 1902, P• 342; 1908, p. 667. 
Rochester Academy of Science, Proceedings, v. 3, 1894­1902, P• 241; v. 13, 1906, p. 268. 
Report of British Association for the Advancement of Science, Section K, Belfast, 1902. 
Rosenbuch, R., Elemente der Gestemslehre, 1898. 
Royal Society of Canada, v. 1, Section 4, 1882-3, p. 285. 
Royal Society of Edinburgh, Transactions, v. 39, pt. 4, 1900, P• 907-931; v. 37, pt. 2, 1893; 17, 1889-90, 
p. 79-109; v. 20, 1912, P• 258. 
Safford, J. M., Geology of Tennessee, 1869, p. 458-459. 
Sandy Hook Sheet, United States Geological Survey. 
Science, New Series, v. 33, 1911, p. 550. 
Scott, M. B., Introduction to Geology, 1897, p. 227, 229, 
230. 
Sheldon, J. M. A., c,oncretions of the Champlain Cl8_ys of the C:onnecticut Valley. 
Smith's 	Contributtons to Science, No. 248, p. 1872. 
Smithsonian Contributions, v. 23, article 3, p. 248; v. 23, 1881, pp. 11, 12. 
Smithsonian Miscellaneous Collection, v. 64, 1914-16. 
South Dakota Geologic~l Survey, Bulletin, No. 2, 1909, p. 59, No. 4, 1908, P• 31; No. 5, 1912, P• 31. 
Societe 	Geolog1que de France, Bulletin 3, Serie 3, 1845-46, P• 510, 1844-45, p. 198, 2, Serie, No. 2. 
South Dakota School of Mines, Department of Geology, 1910; Bulletin No. 9, p. 40, 44, 60. 
81 
Technology Quarterly of Massachusetts and Proceedings of the Society of Arts, v. 1, May, 1888, p. 397. 
Tenny, Sanborn, Geology, 1865, p. 205, 206. 
Texas Geological Survey, First Annual Report, 1889, p. 355. 
Texas University, Bulletin No. 246, Ser. 23, 1912, pp. 20, 21, 30, 31; No. 102, Ser. 12, 1908, p. 18; No. 1869, December 10, 1918, pu. 35, 36, 41, 109, 113, 116, 122, 124, 131, 138, 146, 167, 178, 183, 221; No. 1895, p. 87, 88. 
Thompson. Voyage of the Challenger, The Atlantic, v. 1, 
u. s. National Museum, Proceedings, v. 17, No. 987, 1895, 
p. 87, 88. 
United States Geological Survey, Annual Report, 16th Annual 1894,pt. 4, p. 517; 17th Annual, 1895, pt. 1, P• 993; 17th Annual, 1895, pt. 2, p. 569. 
United States Geological Survey, Bulletin 4, p. 26; Bulletin 150, p. 108; Bulletin 148, P• 306; Bulletin 330, p. 82. 
United States Geological Survey, Monograph 13, p. 64; Mono­graph 29, p. 711-718, 720; Monograph 31, p. 206-242. 
United States National Academy of Science, Proceedings, 1919, 
p. 562. 
University of California Publications, v. 11, No. 3. 
University of Kansas Geological Survey, v • . 1. 
Williams, Manual of Lithology, p. 76. 
Zirkel, F., Lehrbuch der Petrographie, v. l. p. 505-514. 
The following references include those which were 
not available in the Library of the University of Texas: 
American Institute of Mining Engineers, Bulletin 24~ p. 1057, November, 1908. 
American Naturalist, v. 18, 1884, pp. 882-892. 
Anales Soc. Espanola fis. quin, v. 10, p. 18-20, J. Casares 

and s. Pena. Annual Report of Indiana, 1897, pp. 105-150. Annual Report of Vermont, 2nd, 1846, pp. 111-118, 140-142, 
255. Beschof, Elements of Chemical and Physical Geology, v. 2, 
1859, P• 130-139. Beschof, Lehrbuch, Band I, p. 134•428. Bourne, E. E., History of Wells and Kennebing, 1875, p. 
119-122. Bulletin of Academy of Imperial Sciences, St. Petersburg, 
Ser. 6, 1840, p. 299-426; 1910, p. 447-80. Canadian Geological Survey, Memoirs 101 & 102. Canadian Record of Science, V. iv, January, 1891. Centralblatt, 1901, p. 698; 1903, v. 2, P• 361. Centralblatt Mimeralogie, 1912, p. 282-7; 1914, p. 641-53; 
1915, p. 257-63. Chemische Centralblatt, 1912, v. 1, p. 1248; 1914, v. 2, 
P• 1468-9. Deut. Med. Wochschr., v. 36, p. 704-6, 1910, L. Lichtwitz. Experiment Station Record, v. 32, 1914, P• 215-216. Geological Magazine, v. 8, December 4, 1901, p. 35-36, 
pp. 149-154, 197-203, 1903; No. 3, December 5, 1906, P• 553; No. 4, 190'7, P• 106; pp.334-335. 
Geological Society of Glascow, Transactions, v. 11, P• 128-31. 
Iron Making in Alabama, Gaol. Survey of Alabama, Second Edition, P• 55. 
Jahresherte des vereins fur materlandische naturkunde in Wurtemburg, Stuttgart, v. 63, p. 355-66, 1917. 
Journal or Geology, v. XVL, P• 452-81 1908. 
King, c., u. s. G. s. of 40th Parallel, v. 2, 1877, P• 84. 
Koenen, Zeitschrift der Deutscher Geologischen Gesellshaft, 

Berlin, P• 381, 1905. 
Lehrbuch der Chem. Phys. Geologie, 2nd Edition, Band l, P• 140. Massachusetts Historical Collection, vol. 8, pt. 4, P• 138. Mittheilungen Landw. Inst., Breslau, v. 6, p. 325-44. M1tthe11ungen der grossverzoglich badischen geologischenLandes am Stalk, Heidelberg, 111, p. 497, 1897. 
Naturw~ z. Forst u. Landw., v. 12, P• 384-92, 1914. 
Neues Jahrbuch fur Mineralogie, Geol. Beilage Band, v. 29, P• 359-405. 
Proceedings and Transactions of Nova Scotian Institute o:r Science, 1895, P• 761. 
Proceedings of Yorkshire Geological and PolytechnicalSociety, v. 12, pt. 3, 1893, P• 245, 246. 
:EToceedings.Royal Society of London, V• 24, 1876, pp. 33, '39, 464, 499, 507; 529. Reader, T. W., C·oncretions :rrom Vancouver Island, British Columbia. Report of Geology or Massachusetts, 1835, PP• 186-187. Report Qf Geology of New York, v. 1837, pp. 232-233. 
Report of Geology of Vermont, v. 1, 1861, PP• 240-245; 
v. 2, 1862, PP• 698-700. Scottish Geological Magazine, v. 6, 1890, p. 471, 472,481. 
84 

Schaffer, F. x., Mittheilungen der Geologischen Gesellshaft, Vienna, iii, p. 300-4, 1910. 
Transactions of American Institute of Mining Engineers, v. 34, 1906, p. 39. 
Transactions GeologicBl Society of London, v. 4, 2nd Series, pt. 2, 1836, p. 103. 
Transactions Manchester Geological Society, v. 22, 1892­1893, p. 436-439. 
Verslag. Konigliche Akademie Westenshappen, v. 23, 1915, pp. 1058-73. 
The following references are to be found in the 
main bibliogrnphy, but they contain much of the material 
that is useful in a study of such deposits as I have de­
scribed. They have been grouped together so that one inter­
ested in the subject may obtain the principal facts about 
concretionary growth and the discussion of problems and 
effects accompanying growth: 
American Journal of Science, 2nd Series, v. 4, 1847, p. 379. 
Bulletin of Museum of Comparative Zoology, Cambridge College, 
v. 17, 1889, p. 121-170. 
Coral Reef of Hawaiian Islands, Bulletin of Museum of Comp. Zoology, Cambridge College, v. 26, 1893, PP• 1-203. 
C.oral Reef of the Tropical Pacific, Memoirs of the Museum of Comparative zoology. Harvard College, v. 28, 1903. 
Daly, R. A., The Calcareous Concretions of Kettle Mill Lambton County, Ontario, Journal of Geology, 
v. a, 1900. 
85 
Florida 	Elevated Reef, Bulletin of Museum of ComparativeZoology, v. 26, 1895, pp. 205-81. 
Florida 	Reefs, Annual Report of the Superintendent of the Coast Survey, 1851, pp. 145-160. 
Garwood, E. J., On the Origin and Mode of the Formation of the Concretions in the Magnesian Limestone of Durham, Geological Magazine, New Series, Dec. III, v. 81 1891, Piil• 433-440. 
Glance Bay, Cape Breton Geology, Acadian Geology, J. w. Dawson, p. 676. 
Grabau, 	A. W., The Transverse Group of Michigan, Annual Report of Geological Survey of Michigan, 1901. 
Julien, 	A. A. Humus Acids, Action. American Association for Advancement of Science, v. 28, 1879. 
Long, E. T., The Pormation of Salt Crystals from a Hot Saturated Solution, American Journal of Science, Series 4, v. 43, 1917, p. 289. 
Moore, E. s., Iron Formation on Belcher Islands, Hudson Bay with Special Reference to the Origin and Associated Limestones. Journal of Geology, v. 26, 1918. 
Maury, c. J., A Calcium Carbonate Concretionary Growth in Cape Province, American Journal of Science, v, 44, P• 369-70, 1917. 
Natural 	History of New York, Part 4, G~ology, pp. 82, 125, 
409. 
Observations on Some of the Strata between the Chalk and the Oxford Oolite in the Southeast of England.Geological Transactions, v. 4. 
Proceedings of the Boston Society of Natural History, v. 6, P• 132ff. . . 
Rhoddy, 	J. H., Concretions in Streams formed by the Agencyof Blue-Green Algae and Related Plants. American Philosophical Society, of Society Proceedings, v. 54, 1915. 
Sheldon, J. M. A., Concretions of the Champlain Claysof the Connecticut Valley. 
Stocks, 	H. B., On the Origin of Certain Concretions in the Lower Coal Measures. Geological Journal, 
v. 58, 1902, p. 46-58. 
Stopes, 	M. c., & Watson, D. w. s., On the Present Dis­tribition and Origin of Calcareous Concretions in Coal Seams Known as ''Coal Balls." Philos. Trans. of Royal Society, Ser. B. PP. 16'7-218, 1909. 
Taber, Stephen, The Growth of Crystals under External Pressure. American Journal of Science, Ser. 4, 
v. 41, 1916, p. 532. 
Todd, J. E., Concretions and their Geological Effects. Bulletin of Geology Society, v. 14, 1903. 
Tortugas and Florida Reefs, American Naturalist, v. 1'7, 
p. 126'7-68. 
Tortugas and Florida Reefs, American Academy of Arts and Sciences, Memoirs, v. 11, p. 10'7-134. 
Twenhofel, w. H., Pre-Cambrian and Carboniferous AlgalDeposits. Americw Journal of Science, v. 58, November, 1919. 
Walcott, D., Pre-Cambrian Algonkian Algal Flora. Smithsonian Miscellaneous Collections, v. 64, 1914-1916. 
Willcox, o. w., The Iron Concretions of the Red Bank Sands, Jou:mal of Geology, v. 14, 1906. 
Wollacott, David, Geology of Northeast Durham and Southeast Northumberland. Proc. of Geol~iats Association, v. 24, 1913.