B185-118-3m 
University of Texas Bulletin 

No. 1750: September 5, 1917 
Bureau of Economic Geology and Technology 
J. A. Udden, Director 
The Geology of Camp Bowie and Vicinity 
By 
:ELLIS W. SHULER 
Professor of Geology, Southern Methodist University 

Published by the University six times a month and entered as 
second-class matter at the postoffice at 
AUSTIN, TEXAS 

The benefits of education and of useful knowledge, generally diffused tlu·ough a community, are essential to the preservation of a free govern­ment. 
Sam Houston 
Cultivated mind is the guardian genius of democracy. . : . It is the only dictator that freemen acknowl­edge and the only security that free­men desire. 
Mirabeau B. Lamar 
THE GEOLOGY OF CAMP BOWIE AND VICINITY · By ELLIS w. SHULER 
The Landscape Around Camp Bo'wie 
A most interesting landscape greets the eye from the soldier tents of Camp Bowie on Arlington Heights. To the north, be· low precipitous cliffs, lie the broad bottom lands of the West Fork of the Trinity River. On the south and east. gradual slopes lead down to the narrow :flood plain of Clear Fork, which encircles the heights and joins the larger stream from the north­west. To the east,. across the flood plain, on a broad rock bench of white limestone forty or fifty feet above the river, lies the city of Fort Worth; while beyond the city is seen a low tree­topped ridge which runs southward, fading into the distance. 
, Southward and again far to the north across the stream bot­toms, stretches a vast rolling prairie, covered, save in a few abrupt breaks of bare white rocks, with grass and bunches of grazing cattle. To explain and put a meaning into the land­scape is the purpose of this article. 
Study of the Landscape Important to the Soidier 
While to the tourist a · knowledge of the landscape adds to his pleasure and to his intellectual development, to the soldier a knowl-edge and study of the landscape•is of far more vital importance; for the line of march and the field of battle is chosen, not by man, but by nature. The spectacular campaigns of Stonewall Jackson in Virginia were only possible through a most intimate knowledge of the topography of the country in which he fought. Armies reckon not only with armies but with fortifications of nature as well. The present highly specialized trench warfare along the Western Front can be conducted only in those areas where the land is covered with deep soils, soft limestones, or shales. 
This bulletill' is written in the hope that it will. prove an incentive to an interest in the things in nature near at hand around Camp Bowie, and thus that it may reliev~ in part the 
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tedious routine of camp life; but most of all it is written to put the soldier on guard, if he would 'fight his enemy to conquer, that nothjng is trivial or to be despised which gives the soldier an insight into the landscape. 
The scout, to detect the camouflage, must know what is normal in the landscape; the artilleryman must know not only the heights and slopes, but the kinds of rock and the effect of shell explosion on each; the airman must be able to interpret in· terms of hill and valley every splotch of color below him; the attacking party must know whether or not it is possible to dig in; while the general who attacks or defends must, marshal every form in the landscape to his defense. 
It seems a singularly fortunate, or most probably a deliberate, choice in the location of Camp Bowie, that the topography around this camp ii> the same type of topography found along much of the Western Front, and that the underlying rocks are similar, in geologic age, in hardness and texture,. and in the kind of fossil life entombed within, to 'those to be seen along the Marne, around Lens, Vimy, Arras, and others of the hard fought battlefields of France. 
Time as a -.B'actor in the Landscape 
The earth is old; so old that the imagination fails to com­prehend or grasp its age. · Measured in units of the earth's revolutions around the sun, or by the lifetime of man, the es­timate of fifty millio:rTs of years gives a most inadequate con­ception. Yet, while the earth is old, the face of the earth is ever being changed and modified under the force of land sculp­ture in the air and in the waters. But this flow from form 
I 
to form in the landscape is not the result of caprice or blind chance. It is thus possible to understand and to interpret a landscape; to know both how it came into existence and what will be its final form. To make this interpretation, it is neces­sary to know the climatic conditions of the area, and the under­ground structures. The supreme importance 0£ underground structure will be seen at once in the general principle that, in an area underlain by alternating hard and soft rocks which come to the surface, the outcrops of the harder rock will locate 
The Geology of Camp Bowie and Vicinity 
the elevations, the m<mntains and hills, while the soft rock will locate the depressions, or valleys and plains. 
Rocks and Rock Structiires Underlying Camp Bowie. 
One of the chief assets of .the city of Fort.Worth is that it has a large supply of artesian water. To secure this supply, many deep wells have been drilled; and, by experience and math­ematical calculations, the drillers know how deep they must drill and the kind of rock through which they must pass until they strike the water sands. :F'rom the data secured from the wells of the cities of Fort Worth, Arlington, Dallas, and other localities near by, and from a study of the attitude and charac.ter of the rocks which come to the surface in the surrounding areas, quite accurate knowledge has been · secured both of the rocks and of the rock structures down to certain depths underneath the region around Camp Bowie. 
In figure 1 is given an idcali?:ed section and birdseye view of the country from Camp Bowie eastward to Dallas. This sketch is known as a block diagram. The area is represented as a block .sawn out of the crust of the earth, so that the' underlying rock structure is shown in the edge of the block, while the surface topography is shown on the· top of the block. It is thus possi­ble to see at a glance the causal relation between the underly­ing rock structure and the configuration of the surface of the land. 
One of the deepest artesian wells in the area above described was recently bored on the campus of the Southern Methodist University, at Dallas. (See United States Geological Surve;v Bulletin No. 629.) T.his well is 2,850 feet deep. From top to bottom the following rooks were encountered: chalk, 159 ft. ; clay, shale and gumbo, wi\}i some lime, 507 ft.; sand and in­terbedded clays, 326 ft. ; ·limestone, 377 ft. ; limestone, 194 ft. ; sand and clays, 207 ft.;' limestone, 469 ft.; and sands, 106 ft. 
Going from Dallas westward, the order of appearance of the rocks at the surface is chalk, shale, sand, limestone, limestone, sand, limestone, and sand, until the rocks in Palo Pinto County are reached, which are quite different in hardness and in gen­eral position. The fact that the series of rocks in the well-sec­
QAJ5 'cLI FF GRAND .PRA IR J·E ARLINGTON 
HANDLEY 
FT.WORTH CAMP BOWi E
1 . s
2 3 4 5 

Figure 1. Bleck diagram showing the underground structure and surface to11ography, the cuestas, in the vicinity of Camp Bowie. 
The Geology of Camp Bowie and Vicinity 
tion at Dallas is the same as the outcropping series, as one goes: westward, gives the clue to the underground structure. Itis evi­dent that the outcropping beds, in the form 0£ great sheets of rock, dip beneath the surface to the east,-and at Dallas lie at vatjous depths below the surface ; the bed outcropping. farthest to the west being buried deepest under the city of Dallas. This is shown in the block diagram in figure 1. Well-drilling is thus a mathematical problem in which is given the distance along the surface and the angle of dip of the beds under ground; required, to find the depth of any bed at a given point. 
For convenience, the geologist has given names to the beds or sheets of rock, usually from the l.Dcality where the best ex­posures occur or where the formation is first described in print. The chalk at Dallas is part of a great sheet of chalk which was first described from its occurrence around the city of Austin. The shales below the Austin chalk are called Eagle Ford, from a little town by that name to the west 'of Dallas. Other forma­tion names are given in the same manner. The :formations re­corded in the well above and in the successive series of rocks appearing to the west of the well, have been given the following names: Austin Chalk; Eagle Ford Shales; Woodbine Sands; Fort Worth, Preston, and Goodland Limestone; Palux)· Sands; Glen Rose Lim"estone, and Trinity Sands. The series of rocks above described belong to the Cretaceou~ Period. Underneath this series lie much ·older rocks belonging to the Paleozoic Period of geologic time. 
The Cuestas 
In a region where the beds dip at a low angle in. one general direction,· if there is a difference in the resistance of certain of . the beds to erosion, that is, if they are harder than the others, such beds will give rise to hills, while the valleys will be etched 
•out on the softer beds. The hills will have on the side toward which the beds dip a long gentle slope, and on the other side a short steep slope. Such an unsymmetrical hill is called a cuesta. 
As is seen from figure 1, between Dallas and Fort Worth there are three cuestas, two of which are important topographic­
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features. 'rhe most striking cuesta is 'that developed on the 
Austin chalk. The cuesta ·developed on the Woodbine sands is 
equally important, but it is not so typical an exampk as that 
of the Austin chalk. 
The Austin chalk cuesta stands in relief, because the chalk is 
more resistant than the underlying Eagle Ford shales which out­
crop to the west of it. This cuesta, viewed from Dallas, shows a 
long gentle slope upward, which is covered by the city of Oak 
Cliff; viewed from the west, as at Grand Prairie, the short 
steep slope has the appeararice of a mountain range in. the 
distance. 
The cuesta on the Woodbine sands is due to the fact that the 
limestones to the west are carried away in solution faster than 
the sands which stand up in a line of rounded hills capped 
with ferruginous sandstone and covered with timber. These 
hills, however, show the cuesta . topography in that the steeper 
slopes face the west. The cuesta on the Woodbine sands bounds 
the ·eastern horizon from Camp Bowie across th~ city of Fort 
Worth. 
Underneath the Woodbine sands lie the soft Denison beds, 
which make a part of the steep slope of the Woodbine cuesta. 
Below the soft Denison beds is found the Fort Worth limestone, 
a notably harder layer.. This, again, underlies' the long gentle 
' rolling slope of the next cuesta to the west upon which Camp 

Bowie is located. 
Prairies and Cross-Timbers 
With the exception of the topography developerl on the Woodbine sands, the prairies are located on the long gentle slopes of the cuestas. Thus, in going westward, one passes . over the Black Pral.rie on the Au~tin chalk, the Eagle Ford Prairie on the Eagle Ford shales, and the Grand Prairie on the Fort Worth limestone. Prairie lands lack forests, and are us.ually covered with fine black residual soils. Just why the prairie lands are not timbered is a problem which has been variously explained, but that it -is dependent upon the char­acter of the soil, soil texture, and drainage rather than cli­mate, seems quite evident, since in the belts where the Wood­
The Geology of Camp Bowie and Vicinity 9 
bine and Trinity sands come to the surface under the same con­
ditions of climate there is a thick covering of timber. 
These two belts of timber-covered sands have been called, 
respectively, the Eastern and Western cross-timbers. The cross­
timber belts are of much less importance as farming lands than 
the prairies. As a source for lumber, they are of small value 
also, except for ofirewood, since the main fore,st growth is of 
stunted post oak, black jack, hackberries, and a few elms. The 
two belts are, however, of tremendous economic importance in 
that the outcrops of these sands in the cross-timbers form the 
catchment area for the great artesian water supply under the 
prairies. 
Cuesta Topography in Fran-ce 
Particular attention is called to the cue,sta topography be­cause of the vital part this land form has played in the de­fense of France; for, fortunately, the heat of France, the country around Paris, is protected by encircling rims of hills, the steeper slopes of which face outward and form natural fortifications against an invading army. 
1 
This topography is due to the fact that the structure of the rock formations underlying that part of France, the so-called Paris Basin,· has the form of nested bowls, individual forma­tions coming successively to the surface in passing outward from the city of Paris. The rocks dip back toward Paris at low .angles, and thus erosion has developed successive rims of cuesta ·hills on the harder formations, with the steeper slopes facing outward. These give commanding heights, with a maximum effectiveness for artillery positions, which can be defended with 
a minimum of ·effort from infantry attacks. 
Again, the landscape in France reflects the underlying rock 
in the soil, the v~getation, and the farming, just as around 
Ca~p Bowie. Belts underlain by sand are forest-covered; clays. 
and shales underlie farming lands; while smooth bare hills are 
found on the chalk. 
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Drainage 
The area around Camp Bowie is drained by the Trinity River and its tributaries. The relation of the drainage to the cuesta hills is the paradox in the landscape, for the river crosses these hills at right angles. The explanation is that the Trinity-River is older than the hills. The land, upon its emergence from the . water, sloped gently toward the Gulf and upon this initial slope of the surface the Trinity had its birth. 
Al:, time passed, the Trinity deepened its valley, and the gen­eral surface of the land was lowered; lateral tributaries etched valleys along the outcrops of the softer beds, while the harder beds were left standing in relief. The Trinity, running in a comparatively narrow valley, has held its original course across the grain of the country, . while the side tributaries, as, for ex­ample, Mountain Creek, Village Creek, and Sycamore Creek, developing later than the main stream, fl.ow parallel to the grain' of the country along the steeper front of the cuestas. 
This featur~, again, has military value, since in aCuesta top­ography these major transverse streams offer the line of great­est strategic weakness, and along such streams the invading armies must be resisted and repelled. The River Marne is thus one of the lines of easy advance into the heart of France, and its defense has been glorified by the death of many a brave Frenchman. 
ROCK FORMATIONS AND FOSSIL CONTENT AROUND CAMP BOWIE 
Fort Worth Limestone 
The white limestone which underlies Camp BoWie and the rolling hlUs of Grand Prairie has been named the Fort Worth limestone, or more properly the Fort Worth formation, because the city of Fort Worth is built upon it. . Lithologically, the formation is made up of a series of alternating beds of hard and soft limestones, the hard layers spaced about eight to twelve inches apart wlth the soft layers between. When the rock is exposed to the weather, the softer beds are etched back, while the harder layers stand out in relief, and thus outcrops of the Fort Worth limestone show a characteristic ribbed aP· pearance, such as is seen in fignre 2. Fort Worth is the type 
The Geology of Cavnp Bowie and' Vicinity 
' Figure 2. Fort Worth Formation, F\Jrt Worth, Texas 
. I 
locality for the formation, .and many excell~nt exp<>smes are to be seen about the city, as in the' railway cuts near the Union Station; Trinity River bluffs, where the bridges cross to Arling­.ton Heights, and to North Fort W,orth; Forest Park; Sycamore Park, at' the foot of Polytechnic Heights; and many exppsures 
around the site or Camp Bowie and Lake . Como. 
The Fort Worth formation underlies the Grand Prairie, ~hich ­differs from other Texas prairies in that it has a distinctly roll­ing topography. 
The limestone, except for an ocasional bare spot where the 
white .rock comes to the surface, is covered by a thin brown o,~ black chocolate soil, whiGh on account of the shallowne~s is left ·a natural pasture, and the area is generally cover,ed with cattle 
ranc4_es. . ' 
Fossils in the .Fort Worlh Lirn~stone.
I/I ' . . • . .. 
A fossil is the imprint or remains of an animal or plant which is found in a rock. The fossil remains found in the Fort Worth 
University of Texas Bttlletin 
limestone are ma:dy and interesting. Fossils are also found in other limestones both above and below, but certain fossils are found only in this formation. These fossils, which are known to geologists as guide fossils, are remains of supposedly short­lived animals, judged by the geological time scale; so short-lived, in fact, that their whole existence is limited to the time during which the beds of limestone were accumulating under the sea. These guide fossils thus become time markers, and rocks which contain these same fossils, whether in Texas, Alabama, or France, are evidently of the same age. Two fossils are espec­ially characteristic of the Fort Worth limestone, Ammonites lconensis and Epiaster clega11s, pictured in Plates I and II. 
The "Leona ammonite" belongs to a sub-group of the shelled animals known as the cephalopods, of which the chambered nautilus is a modern representative. The ammonite shell is like a giant coiled ram's horn, separated into chambers at regular distances by cross-partitions, which join the horn in a wriously ·crinkled jointing. The animal lived in the forward chamber,, and moved and fed itself by means of waving tentacle arms surrounding the mouth. When the animal died, the shell fell to the bottom of the ocean floor, and was buried in the lime mud. But, when the limestone was elevated again on land and exposed to weathering, th_ese shells now fossilized and filled with lime muds were uncovered, and being more resistant to weather­ing than the surrounding rock, now lie on the surface. There are :many sizes and shapes in the ammonitc family, ranging from specimens two or three inches in diameter up to that of Amnwn­ites leonensis, a veritable wagon wheel in size. This big fellow is found by the scores in outcrops armmd Fort Worth. Splen­did examples are to be found along the roads from Camp Bowie to Lake Como, where .broken fragments of the coil, like felloes from a wheel, and many whole shells, lie on the roadside. 
A second fossil especially characteristic of the Fort Worth formation is Epiaster elegans. This "elegant biscuit urchin" belongs to the echinoids, "hedge hog" division of a great group ·of marine animals, of which the star fish and common biscuit urchin is a modern representative. The characteristic feature ·of these animals is the 5-partite division of the anatomy. The 
The Geology of Camp Bowie and Vicinity 13: 
animal ·skeleton is made up of a series of plates which make· 
a dome-shaped roof and a more or less flattened bottom; Many 
forms have a coronet shape. Practically all types were covered 
with knobs and spikes, which probably served fo;r ' protection 
and, in part, locomotion. Epiaster elegans (Plate II, above) is 
usually found beautifully preserved, so that individual plates 
of the skeleton, knobs and bosses, ,and the serial rows , of open­
ings through which tube-like feet were projected, are all found• 
in wonderfu! clearness and detail. Many other ·fossil animals 
are found in the limestone;, such as ancient oysters, marine 
snails, ancient pecten shells, and other types. 
If there is a plant representative among the fossils of the­
Fort Worth ~imestone, it is to be found in the characteristic 
but problematic fossil found on large slabs of the limest~ne, a 
network of crossing, branching, and recrossing ridges in size­
up to finger widths which covers the surface of the rock. These· 
fucoid-like structures are thought by some to be the remains of 
sea weeds~ 
Fo§sils in Other Formations Around Camp Bowie 
. The formatio1's. ooth above and below the" Fort Worth lime­
stone are a full storehouse of fossil wealth, reflecting the varied 
life of the seas during the deposition of' these rocks. West 'or· 
Camp Bowie, underneath the Fort Worth limestone. as, for 'example, along the steep slope where the White Settlement road l~aves Arlington. Heights, are the Preston and Goodland lime­stone beds, full of biscuit urchins, many tiny 'as a thumb-nail; oysters, marine snails, amm~mites, and other types .of fossils. 
To the east and lying above the Fort W o'cth limestone are­
the Denison beds. In going up the ravine from Sycamore Park 
to Polytechnic Heights, many interesting fossil forms are found. 
· The one· which will attract instant atteiition is a bed of .tiny 
oysters which is about two feet thick. Still higher along the 
slope, twenty feet above' the ·Fort Worth limestone, there is 
another characteristic oyster which has a wide distribution in 
Texas. It is known as Gryphaea waskitaensis. This iS shown 

in Plate I, lower figure. 
A close relative of this oyster, but :m'uch larger, is found near 
the top of. the Denison beds, as they outcrop in the deep cut 
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.along the T. & P. Railway near Handley. This oyster is known as Gryphaea mucronata. This is illustrated in Plate II. The list of good collecting grounds around Camp Bowie is· a long -0ne. In addition to the localities mentioned above, should be listed Forest Park, Sycamore Creek, White Rock, and along the road to Benbrook. 
Fossils from the Sand and Gravel Pits 
There is yet to be mentioned a fossil life found in the ancient 
sand and gravel pits around Fort Worth. These sand and gravel 
deposits were laid down by the Trinity River when it flowed 
at higher levels, during the period of Pleistocene refrigera­
tion, when the northern parts of North America and Europe 
were covered with a great ice cap. _ 
At that time, great herds of elephants, mastodons, and ancient 
bison roamed the Texas prairies, just as did the buffaloes with­
in the memory of men living in Fort Worth today. Skulls and 
tusks, jaws, leg bones, and other fragments of these giants of -ancient time are often found in the gravel and sand pits. 
I 
Geological Literature on the; Area Around Camp Bowie 
The above sketch of the geology of the area around Camp 
Bowie is but a brief and non-technical. description. Further 
accounts. are t~ be found in the following references, all of which 
will probably be found in the public librazy at Fort Worth: 
Bulletin University of Texas, No .. 44, "Review of the Geology 
<>f Texas.'' 
United States Geological Survey, Twenty-first Annual Re­
port, part VII, . 
United States Geological Survey Bulletin No. 629. 
Plate I. Left sld-e: Ammonites Conensis Roemer. From the Fort Worth 
Limestone. 
Right side: Same; a side vi-ew. 
Below: Gryphaea Washitaensis Hill Froin the Dennison b-eds. 

Plate II. Above: Epiaster elegans Shumard. From the Fort Worth Limestone. 
Below: Gryphaea mucronata Roemer. From the Den­nison beds. 



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