DBPAETMBNT OF THE IBTBB1OK

BULLETIN

UNITED STATES

GEOLOGICAL SURVEY

ISTo. 164

WASHINGTON

GOVERNMENT 

 f

PRINTING OFFICE

1900 4-

UNITED STATES GEOLOGICAL SUEVET

CHAELES D. WALCOTT, DIRECTOK

IN THE

' MO GRANDE COAL FIELDS OF TEIAS

BY

Tl-IOMAS VAUG-HAlSr

INCLUDING A REPORT ON IGNEOUS ROCKS FROM THE SAN CARLOS COAL 

FIELD, BY E. C. E. LORD

WASHINGTON

GOVERNMENT PRINTING OFFICE

. 1900

CONTENTS

Letter of transraittal....................................................... 9

'Introduction.............................................................. 11

I. EAGLE PASS AND EOCENE COAL FIELDS OF THE MIDDLE Eio GRANDE KEQION.

Definition of area......................................................... 13

General physical features ......................................... '. ....... 13

, Descriptive geology....................................................... 15

Cretaceous........................................................... 15

Kio Grande section............................................... 15

> Lower Cretaceous (Comanche series) ............................ 16

Edwards limestone........................................... 16

Fort Worth limestone ......................................... 16

Del Eio clays ................................................ 17

Buda limestone .............................................. 18

> Upper Cretaceous.............................................. 18

Dakota division (absent)..........................."........... 18

Eagle Ford formation......................................... 18

Austin chalk................................................. 19

Upson clays...................................1............... 20

Eagle Pass formation ..................""........................ 21

San Miguel beds.......................................... 21

Coal series............................................... 22

Escondido beds .......................................... 26

rl Re'sume' of characters and thickness of the Eagle Pass formation ................................................ 28

Reconnaissance from Cline, Uvalde County, to Eagle Pass........... 28

Reconnaissance from Eagle Pass to Carrizo Springs ................. 30

Studies along Turkey Creek and the Nueces River, the Frio and Sabinal 

rivers, Brackett and Uvalde quadrangles (eastern Kinney County

.and Uvalde County)............................................ 31

Anacachp formation.......................................... 31

Eagle Pass formation in Brackett and Uvalde quadrangles....... 33

Variations in character of the formations in the different sections.... 34

Anacacho formation and Upson clays.......................... 34

Eagle Pass formation ......................................... 35

. Relation of the Cretaceous to the Eocene .......... 1............... 35

i Rio Grande section ........................................... 35

Between Eagle Pass and Carrizo Springs ....................... 35

Along the Nueces River....................................... 36

Along the Frio River ......................................... 36

Tertiary ............................................................. 37

Eocene.......................................................... 37

Rio Grande section........................................... 37

Reconnaissance between Eagle Pass and Carrizo Springs and

southwest of Carri/o Springs ................................ 40

» 5
6 CONTENTS.

Descriptive geology Continued. ' Page. 

Tertiary Continued. 

Eocene Continued.

Reconnaissance from Carrizo Springs to San Lorenzo Creek ..... 47 ^

Nueces River section......................................... 47 ^

Reconnaissance from Uvalde to Carrizo Springs and from Carrizo

Springs to Santo Tomas..................................... 50

Frio River section............................................ 51

Conclusions regarding the Eocene ............................. 53 *

Neocene and Pleistocene.......................................... 54

Neocene..................................................... 55

Pleistocene .................................................. 55

Economic geology........................................................ 55 \

Eagle Pass coal field.....^............................................ 55

Extent .......................................................... 55

Mines ........................................................... 60 ,

Character of coal.............................. 1.................. 60 ; '

Eocene coal fields .................................................... 61

Extent of the Eocene coal fields, including the Santo Tomas field..... 61

Mines ........................................................... 64

Character of coal................................................. 64

Conclusions regarding the Rio Grande"Eocene coals................. 66

Literature ............................................................... 67

II. SAN CARLOS COAL FIELD.. "V

Introductory note .......................................................^ 73

Geographic position of localities studied ................................... 73

Literature ................................................................ 74

Topography and structure ................................................ 74

Sections studied and notes thereon ........................................ 76

Peak 6 miles west of south from Chispa................................ 76

Sections in the vicinity of San Carlos .................................. 77

Vieja Mountains east of San Carlos ................................ 77 i

Fossils from same ............................................ 78

Detailed section through coal seam ............................ 79

Arroyo northeast of shaft of San Carlos Coal Company.............. 80

Fossils from same............................................. 80

Overturned fold north of shaft of San Carlos Coal Company ......... 80

Fossils from same ............................................ 81

Sands and clays.................................................. 81

San Carlos and arroyo above ...................................... 81

Gettysburg Peak ................................................. 81

Re"surn6 of San Carlos section........................... r .......... 81

Age of fossils below the coal ....................................... 82

Bracks Canyon................................................... 82

Geographic distribution of quartz-pantellerite ......... .^T............... 83 ^

Correlation of the Chispa and San Carlos sections....................... 83 '

Time of the volcanic outbursts .................................... 83

Dikes............................................................ 83

Strata below the San Carlos formation ................................. 84

Extent of San Carlos and other Trans-Pecos Texas coal fields and condition of

mining ................................................................ 85

Character of San Carlos coal, including analyses ........................ 87

Report on igneous rocks, by E. C. E. Lord................................. 88
ILLUSTRATIONS.

Page.

PLATE J. Map of the region of the Eagle Pass and Eocene coal fields of the 

i Middle Kio Grande in Texas.................................. 13

II. The Rio Grande, from Mexican side of the river opposite Eagle Pass. 26

III. A, Cretaceous-Eocene contact on the Frio River, 2 miles below 

Engelmann's ranch, southern Uvalde County; B, Basal Eocene 

bluff on the Frio River......................................... 50

( IV. A, Lower Eocene sandstone on the Frio River; J3, Artesian well,

Dinman's place, near Carrizo Springs ........................... 52

1 V. Bluff of Rio Grande at Eagle Pass, showing the upper plain (Uvalde 

formation level) and the wide silt terrace (Columbia formation 

level) ........................................................ 54

VI. Map showing the topographic features of the San Carlos region and 

J the localities described in this report ........................... 74

i VII. View of the Vieja Mountains looking south from Chispa........... 76

^ VIII. View of the Vieja Mountains looking east from San Carlos......... - 78

j IX. View of Gettysburg Peak from San Carlos......................... 80

X. Bracks Canyon, entrance to eastern end, San Carlos ............... 82

XI. Columnar sections............................................... 84

FIG. 1. Map showing the general position of the Rio Grande coal fields ..... 14

2. Section of hill on east side of Elm Creek, 1 mile above bridge, at the

crossing of the Del Rio and Eagle Pass road...................... 23

3. Section of the Eagle Pass artesian well............................. 25

4. Section of the Anacacho Mountains, Kinney County ................ 32

: 5. Weathering of the Carrizo sandstone at Chupadero ranch........... 53

6. Sandstone and clays above coal horizon (Santo Tomas seam) at Santo

Tomas..................................... 1................... 54

_/ 7. Section of bluffs and terraces at Palafox............................ 55

8. Generalized diagram of Rio Grande terraces......................... 55

9. Sketch map showing coal mines and prospects near Eagle Pass....... 56

7

LETTER OF TRANSMITTAL.

DEPARTMENT OF THE INTERIOR,

UNITED STATES GEOLOGICAL SURVEY,

Washington,!). C.; May 14, 1899.

SIR: I submit herewith for publication a manuscript by Mr. T. 

Wayland Vaughan, entitled Reconnaissance in the Rio Grande Coal 

Fields of Texas. This paper treats of two areas, both of which, in 

addition to the economic considerations, are of scientific interest, inasmuch as they give interesting types of the geology of the localities 

studied.

The first of the areas embraces that portion of the Lower Rio Grande 

region lying between Del Rio and Laredo, and treats of a section of the 

Cretaceous and Tertiary formations and of the relations of the one to 

the other. This section has been an object of interest for many yea^s, 

and, as shown in the literature cited by Mr. Vaughan, has been visited 

by many geologists. As the region is a transition ground between the 

phases of these formations hitherto considered peculiar to the Rocky 

Mountain and the Atlantic Coastal plains, respectively, such a section 

must necessarily throw some light upon the relations of the formations, including the age position of those hitherto ascribed to the 

Laramie epoch. Mr. Vaughan could hardly be expected to solve completely all the problems of the region in the short period of time during 

which he'was permitted to examine it, but his paper will be a valuable 

contribution to a "progressive series of researches which have been 

made in that territory.

The second paper treats of the San Caiios coal field in Trans-Pecos 

Texas. This paper, too, is of great scientific interest, inasmuch as it 

gives a detailed section of the Cretaceous beds of the Vieja Mountains 

of the Trans-Pecos region, and also throws light upon the occurrence 

of interesting volcanic rocks.

Mr. Vaughan has treated the economic features more briefly than 

he would have done if the determination of the stratigraphic position 

of these coals had not been the principal object of these preliminary 

reconnaissances.

Very respectfully, ROBT. T. HILL,

Geologist. 

Hon. CHARLES D. WALCOTT,

Director United States Geological Survey.

RECONNAISSANCE IN THE RIO GRANDE COAL FIELDS OF TEXAS.

By THOMAS WAYLAND VAUGHAN.

INTRODUCTION.

One of the most important economic questions with which Texas 

has to deal is that of coal supply. Although it embraces 250,000 

square miles of territory, and is by far the largest State in the Union, 

in 1897 it stood nineteenth in the scale of coal producers. For manufacturing enterprises and railroads coal is one of the first requisites; 

therefore in the following paper an attempt has been made to state all 

that is known of the coal fields of the Rio Grande region. Two reconnaissance trips made jointty with Mr. T. W. Stanton, under instructions received from Mr. R. T. Hill, during the field season of 1895; a 

reconnaissance made in 1898 in company with Prof. William L. Bray, 

of the University of Texas, who was studying the flora of western 

Texas; and a certain portion of the notes accumulated while mapping 

the geology of the Brackett quadrangle, as assistant to Mr. E,. T. Hill, 

and later while mapping the geology of the Uvalde quadrangle, serve as 

a basis for this report, but all available information has been utilized. 

The fact that this report is, as a whole, the result of reconnaissance 

work and that it is not based upon a detailed study of the coal fields 

herein treated, should be emphasized.

Mr. Stanton has determined all of the Cretaceous fossils discovered, 

except a few Foraminifera, and has contributed his conclusions concerning the age of the beds. The Eocene fossils were determined by 

the writer.

The general plan of the discussion followed is: (1) The general 

geology of the coal fields and adjoining areas; (2) the distribution of 

the coal and the present condition of mining; and (3) the physical and 

chemical characters of the coal.

Several coal-bearing areas have been recognized in the region adjacent to the vallejr of the Rio Grande in New Mexico and Texas. 1 The

i Coal fields of Colorado, by R. C. Hills: Mineral Resources U. S. 1892, pp. 319 et seq. 

New Mexico, Its Resources, etc., New Mexico Bureau of Immigration, Santa F<j, 1884. 

The Cerillos coal field, by John J. Stevenson: Trans. New York Acacl. Sci., Jan., 1890, pp. 105-122. 

Mr. T. W. Stanton has made an examination of the White Oaks mine, and informs the writer that 

the coal there is probably Laramie.

' ' 11
12 EIO GRANDE COAL FIELDS OF TEXAS. [BULL. 164.

first of these includes a number of isolated or limited districts in New 

Mexico, to which belong the Cerillos, Bernalillos, and Fort Bayard 

fields, which are probably of the same age as the so-called "Larainie'2 

coals of Colorado, viz, uppermost Cretaceous and transitional Cretaceo-Tertiary. -The second area is situated in the Vieja Mountains, 

in the vicinity of San Carlos, Texas. These coal beds are of Pierre age. 

The third area occupies the interior portion of the Rio Grande Plain, and 

extends from the Santa Rosa Mountains of Mexico to beyond Eagle 

Pass, Texas. Mines are worked in it near Eagle Pass, Texas, and near 

San Felipe, Sabinas, Fuente, and Porfirio Diaz, in Mexico. The coal 

of this area is of Fox Hills age. Associated with it is a fossil 

plant, Geonomites tenuirachis^Lix., which also occurs in the "Laramie" 

coal of New Mexico. The marine fauna is equivalent to that of the 

Ripley and Navarro beds of the Gulf region and to that of the Fox 

Hills beds of the Rocky Mountain section. The fourth area is the 

coal field adjacent to Santo Tomas, Texas. These coals are usually 

lignites of Eocene age.

In addition to the districts mentioned, adjacent to the valle}^ of the 

Rio Grande, allied beds are found in the Trinidad-Raton district of 

Colorado and New Mexico and in the White Oaks district of the 

Sacramento Mountain reedon of New Mexico.
U.S.GEOLOGICAL SURVEY BULLETIN NO. 164 PLI

MAP

SHOWING LOCALITIES WHERE 

COAL IS FOUND

IN THE

MIDDLE LOWER RIO GRANDE REGION

BY T.W.VAUGHAN, 1898

ORANCHES MINES

-COAL s -'~^-APPROXIMATE EOCENE-CRETACEOUS

A.Hoen X- Co. Llth.BolHino
[.-EAGLE PASS AND EOCENE COAL FIELDS OF THE MIDDLE 

RIO GRANDE REGION OF TEXAS.

DEFINITION OF THE AREA.

This part of this report is based upon a reconnaissance, made in 

1895, of the Rio Grande region from Del Rio, in Valverde County, to 

Santo Tom as, in Webb County, thence to Uvalde, in Uvalde County; 

and upon a second reconnaissance, made in 1898, from Cline, Uvalde 

County, to Eagle Pass, thence up the Rio Grande to Upson, across 

to Paloma, back to Eagle Pass, and from the last-mentioned place to 

Carrizo Springs, thence to the Rio Grande at the Webb-Maverick 

county line. After returning to Carrizo Springs the return journey 

to Uvalde County was made along the Nueces River. Besides the data 

accumulated on these reconnaissance trips some data obtained while 

studying the geology of the Brackett and* Uvalde quadrangles have 

been utilized.

The area is approximately a right-angled triangle, the apex being at 

Santo Tomas; the layppthenuse, the Rio Grande; the base, a line from 

Del Rio to Uvalde, and the third side a line from Uvalde to Santo 

Tomas. It embraces portions of Kinney, Valverde, Maverick, Webb, 

Zavalla, and Uvalde counties. (PI. I.)

GENERAL PHYSICAL FEATURES.

These coal fields lie within the geographic province of the Texas 

region denominated the Rio Grande Plain. 1 This plain is a local modification of the southwestern attenuation of the coastal plain of the 

Gulf and Atlantic States, comprising a western prolongation of the 

same up the Rio Grande, included in the angle formed by the convergence of the Balcones escarpment line and the eastern front of the 

Cordilleran region in Coahuila.

The Texas side of the region is a vast plain, slightly inclined to the 

southeast, sloping from an elevation of 1,082 feet at Johnstone, Val-, 

verde County, to about 600 feet opposite Santo Tomas, or at the rate 

of about 3 feet to a mile. The streams have cut their beds in this plain 

and now lie considerably below its former level.' The larger of these 

stream valleys are accompanied by series of terraces. The structure 

of the Texas portion of the plain throughout the greater part of its 

extent is that of a gently southeasterly dipping monocline. In the

i Hill and Vaughan, Eighteenth Ann. Kept. U. S. Geol. Survey, Part II, 1898, p. 202.

13
14 EIO GRANDE COAL FIELDS OF TEXAS. [BULL. 164.

vicinity of Santo Tomas there is a local exception to the usually uniform direction of dip of the strata. Here the dip, instead of being to 

the southeast, is to the northeast, according to informationxfurnished 

by Mr. D. D. Davis, superintendent of the Cannel Coal Company's 

mine. This disturbance is, without doubt, genetically connected with 

the uplift of the Sierra Santa Rosa of Mexico.

The northern limit of this plain is a great southward-facing escarpment, several hundred feet in height, which has been described 1 under 

the name "Balcones escarpment." Along its foot is a strip of country

FIG. 1. Map showing the general position of the Rio Grande coal fields.

from 6 to 15 miles wide, which is broken by faults and in which there 

has been considerable volcanic disturbance. This scarp is the southern edge of the vast Edwards Plateau. It is composed of practically 

horizontal limestone strata, and attains*an altitude of some 2,500 feet. 2 

The vegetation consists of grasses, which at the time of our visit 

were mostly dead and dry, and of a variety of prickly plants belong1 R. T. Hill: Am. Geologist,Vol.V, No. 1, Jan., 1890, pp. 17-18: Am. Jour. Sci., 3d series, 1887,Vol. XXXIV, 

pp. 291 et seq.

'The geographic features of the region are more fully described in a paper by Mr. Hill and the 

writer entitled The Geology of the Edwards Plateau and Rio Grande Plain: Eighteenth Ann. Rept. 

U. S. Geol. Survey, Part II, 1898, pp. 193-323.
VAUGHAN.] PHYSICAL FEATURES. 15

ing to the Leguminosaa, Rhamnacage, and Cactacae, constituting the 

chaparral of the Mexicans. There are enormous orchards of Opuntia 

rafinesqud, the common prickly pear or nopal of the Mexicans, and 

tasajillo, Opuntia leptoccwtis, is often extremely abundant. Of the 

Leguminosae, the mesquite and several species of acacias are the most 

common. Lignum vitas also is a common and characteristic plant. 

Except along the creeks, where occasionally live oaks grow, there are 

no trees, unless the mesquite reaches a size sufficient to entitle it to 

that name. Professor Bray, of the University of Texas, is making a 

careful study of the flora of western Texas with reference to climatic 

and other natural conditions. Rains are very infrequent, and the 

country is not capable of supporting a dense population.

The following table gives the average annual rainfall at some of the 

more important places, 1 as determined by observations extending 

through several years:

Inches. 

Fort Clark (Brackett) ............................................ 24. 02

 Fort Inge (Uvalde) .............................................. 25.35

Eagle Pass....................................................... 25. 01

Laredo .................................................... rf..... 19.58

The mean annual temperature is as follows:

Degrees (F). 

Fort Clark........................................................ 68. 8

Fort Inge......................................................... 68.7

Eagle Pass........................................................ 72.

Laredo .................................................. ^,........ 72. 9

January is the coldest month, but the average temperature for that 

month at any place is rarely as low as 45°. August and July are the 

hottest months, but the average for these months is rarely as high as 

90°. In the summer, in the middle of the day the heat is intense, but 

at night there is always a refreshing breeze.

DESCRIPTIVE GEOLOGY.

The region as a whole is underlain by a series of rock sheets 

belonging to the Cretaceous and Tertiary periods, which are covered 

to! a considerable extent by surn'cial deposits of silt and gravel. The 

beds will now be described in ascending order.

CRETACEOUS. 

RIO' GRANDE SECTION.

The Cretaceous strata of the Texas region have been divided into 

two great subgroups or series, an upper and a lower. These series 

have been further divided into formations, which are still further subdivisible into individual strata; but for purposes of general discussion 

the formations are the units of the system of classification.

1 Climatic conditions of Texas, by Geu, A. W. Greely : Senate Ex. Doc. No. 5, Fifty-second Congress, 

first session.
16 EIO GRANDE COAL FIELDS OF TEXAS. [nuu,.i64.

LOWER CRETACEOUS (tOMANCHE SERIES) . 

EDWARDS LIMESTONE.

At Del Rio the lowest rocks exposed belong to the Fort Worth limestone, but a short distance above Del Rio, before reaching the mouth 

of Devils River, exposures of the Edwards (Caprina) limestone are 

seen. The canyons of the Rio Grande and Devils rivers in this vicinity 

are cut through it. It is a whitish limestone and occurs in thick ledges.

FORT WORTH LIMESTONE.

Within the breaks 1 of the Rio Grande, on both sides of the railroad 

where it crosses San Felipe Creek and in the valley of the creek to the 

north of the railroad, are good exposures of this limestone. Macroscopically it is rather spit, chalky, and argillaceous, and possesses a 

minutely granular or subflocculent texture. Its color when freshly 

broken is white or whitish, with a yellowish tinge, due to the presence 

of ferruginous matter. It weathers to a grayish or yellowish color. 

The fossils which it contains are frequently ferruginous replacements. 

Microscopically the limestone is composed of minutely crystalline calcite and much flocculent (argillaceous) material. Foraminifera belonging to the Globigerina and Nodosaria types are present in very great 

numbers.

Exposures aggregating a thickness of about 40 feet were seen. In 

its upper part the limestone becomes y.eiy argillaceous and passes into 

a whitish clay which lies at the base of the Del Rio (Exogyra arietina) 

clay.

The Valverde County court-house and jail are built of this limestone. 

Through it the San Felipe Springs burst forth, the water coming up 

along a system of joint planes.

The following fossils were obtained near the San Felipe Springs 

(locality No. 269):

Enallaster texana (Roemer). 

Ivingena wacoensis (Roemer).

Rhynconella ? sp.

Ostrea (Alectryonia) sp.

Lima, two species, probably undescribed.

Neithea occidentals Conrad.

Inoceramus sp., small fragmentary specimens.

Neniodon, two distinct species, undescribed.

Cardium sp. , ' °

Thracia sp.

'Mr. W J McGee defines break as follows: "The 'break' is the head of a small retrogressive 

ravine, a minor water course gradually eating its way back into the upland." Twelfth Ann. Kept. 

U. S. Geol. Survey, p. 434.

What is here called " the breaks 1 ' is a much-indented escarpment that constitutes the outer boundary of the Rio Grande Valley, in a restricted sense, and up to which the general level of the Rio 

Grande Plain extends. The indentation of the escarpment is due to the head-water erosion of numerous small streams which are cutting it away.
VAUGHAN.] LOWER CRETACEOUS FORMATIONS. 17

Scaphites ? sp., several small distorted specimens that may be Olcostephanus

or some other aminonoid genus. 

Turrilites brazoensis Roenier. 

Nautilus texanus Shumard.

DEI, RIO CLAYS.

The top of the breaks of the Rio Grande to the northeast, east, and 

southeast of Del Rio is formed of the Buda limestone, to be discussed later. The slope is composed of the Del Rio clays. Within 

the breaks near Del Rio, to the southeast, is a conical-shaped butte, 

called Lone Hill, also composed of these clays, and they are exposed 

20 miles west of Brackett, on the road to Del Rio, where they are overlain by the Buda limestone.

The following is a section exposed at the old ocher mine 2 miles 

north of east of the Del Rio court-house:

Section at ocher mine 2 miles north of east of Del Rio court-house.

7. Buda limestone capping. Feet.

6. Slope to the edge of the bluff covered with Exogyra urielina, a few feet.

5. Yellowish clay ........................................................... 15

4. Bed clay................................................................. 5

3. Thin indurated sandy layer ............................................... £

2. Red clay................................................................. 10

1. Greenish clays ..................................................... ...... 30

In the lowest stratum are thin, sandy flags containing Equisetum? 

and Nodosaria texana. Exogyra arietina is very abundant throughout 

the section. No. 4 is the bed from which the red ocher has been 

mined. This ocher is usually a vermilion-colored clay.

The section above described illustrates the lithologic characters of 

the beds. At the base, along the contact with the Fort Worth limestone, there is a white calcareous cla}'. Above this bed the clays are 

usually greenish before weathering. When subjected to atmospheric 

action they become yellowish. Beds of red clay occur near the top. 

Frequently the .Exogyra arietina is cemented into slabs by a sandy 

ferruginous matrix. The thickness, as determined by the aneroid 

barometer, is 100 feet.

Although fossils are numerous in these clays, there are but few 

species. The following are the species collected and the localities 

whence they were obtained:

FossUs from SO miles west of Brackett.

Nodosaria texana Conrad.

Pecten, a small undescribed species.

Fossil* from old ocher mine on bluff' % miles north of east of Del Rio court-house.

Nodosaria texana Conrad.

Exogyra arietina Roenier.

Plicatula incongrua Conrad.

Neithea sp., fragments. ^ "

Esquisetum?

Bull. 164 2
18 RIO GRAN0E COAL FIELDS OF TEXAS. [BULL. 164.

BUDA LIMESTONE. 1

Above the Del Rio clays occurs a limestone, which both in its 

stratigraphic position and fts lithologic characters corresponds to the 

Buda limestone of the Colorado River section at Austin. Macroscopically this limestone is hard, and whitish or yellowish in color 

when freshly fracti,r3d. The fracture is conchoidal or splintery. It 

is frequently traversed by minute veins of calcite. Upon weathering 

it becomes yellowish or pinkish; occasionally, on account of the great 

amount of iron contained, weathered specimens may be incrusted by 

hematite. Numerous small red or pink blotches characterize the limestone. Microscopically it consists of minute veins and patches of 

transparent calcite, between which are patches of minutely crystalline 

granular calcite of dark-gray or brownish color, in which angular 

transparent pieces of calcite are embedded. The calcite veins are 

sometimes clouded in appearance, but are lighter in color than the 

bulk of the rock. No well-preserved Foraminifera were observed, 

but there are grayish masses of minutely crystalline calcite that show 

the structure of Foraminifera of the Globigerina type.

Outcrops of this limestone are to be seen northeast, east, and southeast of Del Rio, where it occurs above the Del Rio clays. It is also 

exposed at numerous places on the road from Brackett to Del Rio, 

between Sycamore Creek and the latter place.

Measurements of the thickness of the limestone at Del Rio were not 

obtained, but near Brackett it is about 100 feet thick a little more 

than twice the thickness at Austin.

UPPER CRETACEOUS. 

DAKOTA DIVISION.

. (Absent.)

i EAGLE FORD FORMATION.

The Buda limestone is overlain by a series of flaggy, argillaceous limestones, between the beds of which calcareous shaly layers are frequently 

found. These beds occupy precisely the same stratigraphic position 

with reference to the Buda limestone below and the Austin chalk 

above as do the Eagle Ford shales in central and northeastern Texas. 

The stratigraphic continuity of the beds has been traced from Del Rio, 

by way of San Antonio and Austin, to Red River, east of Sherman. 2

As has been shown, these beds thin from Waco southward toward 

the Rio Grande; the more unctuous and darker-colored shales of the 

lower portion of the north Texas section disappear, and only the

1 In accordance with a suggestion of Mr. R. T. Hill, the name Shoal Creek limestone is here changed 

to Buda limestone, as the former name is preoccupied.

»Robt. T. Hill: Am. Jour. Scl., Vol. XXXIV, Oct., 1887, pp. 291 et seq.; Bull. No. 4, Geol. Survey of 

Texas, Austin, 1889, p. xxvii; Artesian and other underground waters in Texas, New Mexico, and 

Indian Territory, Final Rept. of the artesian and underflow investigation of the U. S. Dept. Agriculture, 1892, p. 124.
VAUGHAN.] UPPER CRETACEOUS FORMATIONS. 19

upper or more calcareous, sometimes arenaceous, horizons (called 

"fish beds" by Shumard, Hill, and others) persist, becoming more 

accentuated.

The local name "Valverde flags" 1 has been proposed for these beds

along the Rio Grande, but there is not sufficient lithologic difference

/ to warrant the use of a separate designation, and the equivalence of

the Valverde flags and the Eagle Ford beds has, as stated, been estabj lished by actually tracing the beds across the area intervening between

the areas to which the two names were originally applied.

Outcroppings of the Eagle Ford flags were seen along the road from 

Del Rio to Eagle Pass, from a point 3 miles southeast of the former 

place until the valley of Sycamore Creek was reached, where they 

were obscured by the debris in the valley. The distance across the 

area of exposures is about 8 miles.

No estimate was obtained of the thickness of this formation in the 

vicinity of Del Eio. Dumble has estimated that it is 600 feet thick. 2 

Near- Brackett it is about 250 feet thick, by actual measurement, so 

that it would seem that the foregoing estimate is probably too great.

AUSTIN CHALKi 3

This formation is a soft, chalky, argillaceous, white limestone, containing a little ferruginous matter in the shape of pyritiferous lumps 

or nodules of marcasite. Sometimes there are alternations of chalky 

layers and calcareous clays. It presents exactly the same lithologic 

and paleontologic characters in the middle Rio Grande region that it 

does in the Colorado River region. A microscopic examination of a 

specimen of the chalk collected 15 miles from Del Rio, on the road to 

Eagle Pass, showed its foraminiferal nature; Globigerina, Textularia, 

and Orbulina were present in very great numbers.

The first exposure was seen about 15 miles from Del Rio, on the 

road to Eagle Pass. Other exposures wereyseen as far as Tulio Creek 

(Las Moras Creek), about 33 miles from Del Rio. Pinto, Cow, and 

Tulio (Las Moras) creeks flow over the chalk where the Eagle PassDel Rio road crosses the streams. On the road from Brackett to Del 

Rio exposures were seen as far as the first crossing over the Southern 

Pacific Railroad.

At the crossing over Cow Creek there is an excellent exposure in a 

bluff, about 25 feet high, composed of layers of chalk, 1 foot or more 

in thickness, alternating with beds of yellow clay. From this place 

the following fossils wer,e obtained (locality No. 271):

Cidaris ? sp., a detached plate. 

Gryphsea aucella Roemer.

i E. T. Dumble: Bull. Qeol. Soc. America, Vol. Ill, 1892, p. 221. 

"Op. cit., p. 229.

3 Dumble has used the name " Pinto " for these beds in this region (Bull. Geol. Soc. America, Vol. Ill, 

1892, p. 222), but, as is here shown, there is no occasion for applying a new designation to them.
20 , RIO GRANDE COAL FIELDS OF TEXAS. [BUM.. 101.

Avicula sp. Of. A. linguiformis E. and S.

Inoceramus digitatus Sowerby=I. undulato-plicatus Roemer.

Inoceramus deformis Meek.

Nautilus sp.

Baculites anceps Lam., the form so identified by Roemer.

Pachydiscus flaccidicosta (Roemer).

Mortoniceras texanum (Roemer).

Schloenbachia dentato-carinata (Roemer).

"This is a typical Austin chalk fauna. The species of Inoceramus 

and Baculites»occur also in the contemporaneous Niobrara limestone of 

the Western interior region. 1 ' (Stanton.)

From an exposure in Tulio (Las Moras) Creek Inoceramtts digitatus 

Sowerby TV as collected.

No estimate of the thickness of these beds was made. Unfortunately, for some distance below Tulio Creek no exposures of the bed 

rock were seen, the road being on the wide alluvial terrace flanking 

the Rio Grande. Dumble estimates that the beds are 1,500 feet thick, 1 

basing his estimate upon a dip of 100 feet to the mile.

UPSON CLAYS.

As shown by Dumble, 2 the Austin chalk is overlain by a series of 

stiff clays, which he calls the Upson clays. The actual contact between 

the two formations was not observed. The following is Dumble's 

original characterization of the formation:

The basal member consists of yellow clay containing calcareous nodules of septarian character, the crevices or septse [sic] of which are filled with dog-tooth spar. 

These nodules occur in large geodic form scattered through the clays, and contain 

Exogyra ponderosa Roemer. Numbers of specimens of these fossils are found iri 

geodes as well as on the hillsides, where they have been left by the disintegration of 

their matrix. The nodules or geodes seem to occupy pretty definite horizons and 

sometimes form benches on the hillsides. The uppermost member of this series, as 

I observed it, 'is a clay shale. 3

About 2^ miles above Lehmann's house (Upson post-office), near 

the water level on the Texas side of the Rio Grande, is an exposure 

only a few feet in thickness.

Section % 1-2- miles above Upson post-office.

2. Clays that weather grayish yellow or greenish yellow.

1. Clays that are white .and chalky on exposure, and seem very like a transition 

from the Austin chalk to the Taylor marls.

The bluffs on the Mexican side of the river, as could be seen with 

field glasses, are composed of dark greenish-yellow clays. In places 

there appear to be indurated layers, but no limestones reminding one 

of the Anacacho beds.

Lehmann states that a well, bored to a depth of 45 feet, near a slough 

just south of his house, has its bottom in a stiff, dark-blue clay which

ifiull. Geol. Soc. America, Vol. 111,1892, p. 229. "Op. cit., p. 224.
UPPER CRETACEOUS FORMATIONS. 21

contains many fossils. Unfortunately none of the fossils were preserved.

An examination of the bluffs of the escarpment bounding the Kio 

Grande Valley east of Upson was made, but no exposure of the strata 

beneath the gravel was found. Along the draws was stiff clay, indicating that the .gravels rest on a clay foundation.

These observations show that there is no Anacacho limestone along 

the Rio Grande, but that the equivalent beds have again assumed the 

character of the Taylor marls of central Texas.

.Assuming the dip of these clays to be 100 feet to the mile (the dip 

of the beds in the vicinity of Eagle Pass) the thickness would be 

about 700 feet the estimate made by Dumble (op. cit.).

EAGLE PASS FORMATION.

The name "Eagle Pass beds" was first proposed by Dr. C. A. White, 

in 1891, in discussing the Cretaceous of the Texas region. 1 Dr. White 

does not define the formation, but considers it equivalent to the 

"Ripley" ^Navarro of Hill) of eastern Texas, and places it above 

the Taylor (Ewogyra ponderosa) marls. Therefore, according to 

White, the base of the Eagle Pass formation would rest on the top of 

the Taylor marls, and the equivalent to these marls, the Upson clays, 

would be excluded from it. Dumble (op. cit.) amplifies the name 

"Eagle Pass beds" by the substitution of the word series, and assigns 

to this series all of the beds from the Austin to the base of the Eocene. 

It is better, in the opinion of the writer, to use the name as White first 

employed it, viz, for those beds extending from the Taylor (Upson) 

marls or clays to the Eocene. The three subdivisions of Dumble are, 

however, recognized, but with the reservation that future study may 

very much modif}^ the nomenclature. As yet no detailed study of the 

area as a whole has been made, and the present attempt is only to give 

an idea of the section along the Rio Grande proper, with approximate estimates of the thickness of the formation and a general idea of 

its variations in the area under discussion.

 San Miguel beds. The following is Dumble's original description of 

these beds:

Resting on the clay shales which form the upper member of the Upson clays, there 

is a deposit of sandstone, thin to heavy bedded, separated by bands of clay, and containing seams of glauconitic material with many fossils, as well as occasional heavy 

beds of clay, especially toward the top. * * * In the Eio Grande section it first 

occurs in the hills north of Carter's ranch, where the hills show exposures of it from 

75 to 100 feet in height. The exposures are excellent for several miles south of this 

point, and a very rich fauna which is now being studied was secured. In the upper 

portion I found Exogyra pondwosa and great numbers of other shells not yet determined. Above this the sandstone becomes more calcareous, and in places is compacted and contains calcareous nodules. Three miles south of the Carter ranch we

1 Bull. U. S. Geol. Survey No. 82, 1891, pp. 116 et seq.
22 EIO GRANDE COAL FIELDS OB1 TEXAS. [BULL. 104.

V

found the teeth and bones of a saurian in the concretions. The materials overlying ' 

this become more clayey, as will be seen by the following section made some 10 miles y 

north of Eagle Pass: . .

Section near Eagle Pass.

Feet.

Sand and silt.... ....................:........................................ 8

Sandstone ............................-....................;................. 2 \

Clays, displaying cone-in-cone structure......................................... 6

Sandstone, with laminae and nodules of calcite..!.............................. 1 \

Clay, to base...................................................v.............. 8

Above this there are sands, with lime and greensand, containing many casts of 

fossils Inoceramus and other bivalves, together with numerous gastropods. This 

continues to a point about 8 miles north of Eagle Pass, below which these strata are 

soon covered by the next newer series of deposits.- 1

Coming up from the creek valley, about halfway between the ranches 

of Messrs. Lehrnann and Burr, ! £ miles north of Paloma siding, on 

the Southern Pacific Railroad, one finds sandstone, underlain by clay, 

exposed in the eastern bluff. The section is similar to that next described, which is seen in corning up from the Rio Grande flat, on the 

way from the Lehmann ranch to Eagle Pass.

Twelve and a half 'miles from Eagle Pass, as the road from Upson 

passes from the silt terrace of the Rio Grande to the plain above the 

breaks of the river, the following section was observed:

Section 18 1-2 miles from Eagle Pans. ^

Feet. x

3. Sand and gravel (Uvalde formation).

2. Soft yellow, grayish, or white calcareous sandstone ...................... 40

1. Yellow clay.

Fossits obtained from No. 2.

Ostrea tecticosta Gabb. L -

Exogyra costata Say?, upper valve only.

Pecten quinquenarius Conrad.

Cucullsea antrosa Morton. \

Crassatella sp. \

Cardium carolinense Conrad.

Cardium (Pachycardium) spillmani Conrad.

Legumen planulatum Conrad. . V

Turritella trilira Conrad.

Anchura rostrata Gabb.

u The above species all occur in the typical Ripley fauna of Mississippi and Alabama. The horizon is about the same as that of the lower I 

marl bed (Navesmk formation) of New Jersey." (Stanton.) f

Coal series. This name has been utilized by Dumble (op. cit.) to ' 

'designate that portion of the Eagle Pass formation which contains the 

coal beds in the vicinity of Eagle Pass. The following sections will 

 uve an idea of the character of the beds.

i Dumble, Bull. Geol. Soc. America, Vol. Ill, 1892, pp. 224, 225.
VAUGHAN.] UPPEE CRETACEOUS FORMATIONS.

Section'in tJi,e Maverick County Coal Company's mine, near .Eagle Pass, as given by Mr.

George Eregg, former manager of the mine.

Feet.

7. Sandstone-.-.....-................--....-...--.--...---..........-....-. 50

6. Clay.............--.--..-....---..-...-.---......--...-.----...-..---.-- 60

5. Sandstone............................................................... 4

4. Coal............-..--..................--.....-......------.....------.- 2

3. Clay .................................................................... 94

2. Coal(worked seam)......-.............-...........--.....-........------ 6

1. Sandstone ....^.......................................................... 14

Total 230

FIG. 2. Section of hill on east side of Elm Creek, 1 mile above the bridge at the crossing of the

Del Kio and Eagle Pass road.

Section oj nill on east side of Elm Creek, 1 mile above the bridge at the crossing of the Del Rio

and Eagle Pass road.

Feet.

7. Soft, fine-grained, irregularly bedded sandstone, containing curious elongate 

tube-like bodies, which stand with their long axes vertical to the stratification planes.......................................................... 30

6. Unexposed gravel-covered slope, the gravel in yellowish sand............. 14

5. Coarse brown or yellowish sandstone, sometimes with white blotches and

containing fossil wood................................................ 5-6

4. Sandy slope, a little gravel on -the surface ...................'............ 45

3. Alluvial terrace of creek, lower rocks unexposed, alluvium probably undeilain by sandstone .................................................... 15

2. Creek bank, soft, cross-bedded sandstone, with ferruginous concretions .... 5

1. Yellow clay to bed of creek...................._........................ 2

Total 117

Above the clay apparently the whole section is composed of sandstone like that at the surface in the shaft of the. Maverick County Coal 

Company's mine.

Along Elm Creek, above the bridge, irregularly stratified sandstones 

and clays containing ferruginous concretions and silicified wood are 

exposed. There is no constancy in the small beds o£ sand and clay; 

they are simply interlocking lenses.

At the old Hartz mine the coal is about 6 feet thick and is both 

overlain and underlain by clays. From the clays above the coal a 

specimen of the palm G-eonomites tenuirachis\^\. determined by Prof. 

F. H. Knowlton to be a Laramie species, as it occurs in the coal-bearing 

Laramie of New Mexico was collected.
EIO GEANDE COAL FIELDS OF TEXAS. [uuu,. 164.'

Section at mine No. 1 of the Fuente, Mexico, coal mines on the north bank of the Rio Escondido, 5 or 6 miles west of Eagle Pass.

J J Feet.

6. Gravel interstratified with sandy clay resting uncomformably on (5)...... 15-20

5. Bluish or yellowish carbonaceous clay .................................. 5 ;

4. Shaly coal.............................................................. 4 \

3. Keddish and bluish clay................................................ 2

2. Coal (worked seam) .................................................... 4-5

1. Clay.

Total ...................................-.I..................... 30-36

Near this mine a .conglomerate, composed of calcareous pebbles and 

calcareous cement, covers the surface between the arroyos.

Prospect shaft No. S of L. F. Dolch & Co., near coal shaft for mine.

Depth.

Feet.

0-64

64-74

74-91

91-93

93-96

96-100

100-104

104-120

120-126

126-132

132-145

145-148

148-151

151

151-176 

176-176J 

176J-181

181-182

182-183

183-183J 

183^-195 

195-198

198-199

199-201 

201-203 

203-210

Material.

ft. in.

Clay......".......................!.......'...... 64 0

Sandstone ^..................................... 10 0

Black clay.......'............................... .17 0

Septaria in clay................................. 2 0

Hard blue sandstone.............................. 3 0

Very hard brownish clay, with some sand ........ 4 0

Blue argillaceous sandstone, with some clay seams . 4 0

Dark bluish-black slate .......................... 16 0

Hard sandstone .................................. 6 0

Dark slate ...................................... 6 0

Black clay ...................................... 13 0

Sandstone ...................................... 3 0

Brown clay, rather hard (had to be blasted).'..... 3 0

Coal............ ..........< . .................... 0 2

Very hard white sandstone ...................... .25 0

Bony coal....................................... 0 6

Clay ........................................... 4-6

Brown slate..................................... 1 0

Bony coal....................................... 1 0

Coal seam ...................................... 0 6

Clay ............ ........I...................... 11 6

Slate and sandstone.............................. 3 0

 Bony slate...................................... 1 0

Sandstone ...................................... 2 0

Bone..................;...-.................... 2 0

Coal..........'.................,................ 7 0

Thickness.
VAUOHAN.] UPPER CRETACEOUS FORMATIONS. 25

I

Section of artesian well bored on the top of the hill % miles northeast of Eagle Pass, between

the Uvalde and Carrizo Springs road.*

Feet.

24. Soil and subsoil..................................... 14

23. Yellow clay........................................ 26

22. Bluish clay......................................... 50

21. Sand, with some gravel ............................. 110

20. Black shale, with 6 inches of coal.................... 60

19. Clayey sand........................................ 70

18. Gray sand.......................................... 30

17. Sand, small gravel.............................. 1... 60

16. Sand............................................... 20

15. Gray slate..............................:............ 30

14. Dark shale. ......................................... 55

13. Coal............................................... 6

12. Dark shales ........................................ 9

11. Whitesand (gas)...:............................... 40

10. Black shale .................'....................... 150

9. Sand and shale ..................................... 15

8. Black shale ........................................ 135

7. Sand and shale (gas)................................ 15

6. Dark soft sand and shale ........... =................. 75

5. Hard gray sand (salt water)......................... 1.0

4. Gray shale .......................................... 50

3. Gray sand.......................................... 10

2. Calcareous clay..................................... 370

1. Dark clay .......................................... 102

10

Total 1,512

FIG. 3. Section 

of Eagle Pass 

artesian well.

Nos. 24 to 8 represent the whole thickness of the Coal series; 

Nos. 8 to 1 belong to the San Miguel beds.

About 100 feet north of Burr's ranch, li miles northwest of Paloina siding, is an exposure of brownish or 

greenish-yellow fossil if erous sandstone underlain by 

clays. The section is of somewhat doubtful strati - 

graphic position, but it would seem to belong* in the 

Coal series, and probably below the coal horizon. 

The following fossils have been determined by Mr. 

Stanton from the collection made here:

Trigonia sp., single cast of a young individual.

Area? sp., single cast of a young individual.

Cardium eufalense Con.?

Tellina sp.

Cytherea? sp.

Veleda lintea Con.? Cominoii at Corsicana.

Mactra sp.

Corbula sp.

Dentalium sp.

Lunatia obliquata M. and H. Common Ripley species.

1 Raport on artesian waters, etc., for Texas west of ninety-seventh degree of longitude, by Frank E. 

Roessler, 1890, Senate Ex. Doc. No. 222, Fifty-first Congress, first session, p. 266.
26 EIO GEANDE COAL FIELDS OF TEXAS. [BULL. 164.

Lunatia sp.

Natica sp. Occurs at Kaufman, Texas.

Fusus sp. Occurs at Corsicana, Texas.

Fusus sp.

Tritonium ? sp. Occurs at Corsicana, Texas.

Trophon ? sp. Occurs at Corsicana, Texas.

Olivella sp.

This fauna seems very closely related to that found 2 miles north of 

Eagle Pass on the Uvalde road, but Sphenodiscus pleurisepta, which 

usually characterizes the upper beds, is absent. The stratigraphic 

position of the exposure near the Burr ranch has not been definitely 

determined, but it would seem to be considerably below the fossiliferous 

horizons in the bluffs east of Eagle Pass.

From Paloma to Thomson's siding sands and clays outcrop in the 

draws, and gravel usually caps the hills.

Escondido beds. Dumble (op. cit.) has proposed the name "Escondido beds " for the sandstones and clays occurring above the Coal series. 

The following sections and notes describe them. (PL II.)'

Just east of the railroad, on the eastern side of Eagle Pass, is an escarpment about 90 feet high, the rocks having a strike due north-south magnetic, and a dip 3° E. This escarpment is composed at the top of a few 

feet of soft, yellowish sandstone, underlain by ledges of hard, brownish, 

ripple-marked sandstone, which is followed by a slope composed of 

some clays, but chiefly of soft, yellowish sandstone. The fossils collected on the U.valde-Eagle Pass road, 2 miles above Eagle Pass, belong 

in the lower part of the slope of this section (see p. 30). The detail of 

the section is as follows:

Section on slope near railroad on the east side of Eagle Pass.

Feet.

5. Soft sandstone............................................................ 10

4. Hard brown or yellowish sandstone..-----.__.__................___..__... 3

3. Soft yellowish sandstone .....................'...................,.... 1 or 2

2. Ledges of hard sandstone, with some soft sandstone......................... 15

1. Sandy clay and soft, greenish-yellow sandstone to base of escarpment, clays 

preponderating......................................................... 60

Total...... T ................................................... '.... 90

From No. 2 the following fossils were obtained (locality No. 273):

Ostrea, two species.

Anomia sp., a minutely costate species.

Inoceramus cripsi var. barabini Mortqn.

Cardium sp.

Pholadomya n. sp.

Turritella sp. Cf. T. saffordi Gabb.

"The only species identified in this lot is widely distributed in the 

Ripley and Montana formations." (Stanton.)

This bed contains an oyster ledge and is the base of Dumble's Escondido beds. 1

ifiull. Geol. Soc. America^ Vol. Ill, 1892, p. 228.
BULLETIN NO. 164 PL. II

ROM MEXICAN SIDE OF THE RIVER, OPPOSITE EAGLE PAbb.
VAUGHAN.] UPPER CEETACEOUS FORMATIONS. 27

Fossils collected 1 1-2 miles southeast of Eagle Puss, on the wad to Laredo

(locality No. 274) 

Anomia sp. 

Camptonectes sp. 

Lima sp.

Trigonarca cuneata Gabb. 

Cardium sp. Cf. C. eufalense Conrad. 

Tellina sp. 

Corbula sp. 

Dentalium sp.

Sphenodiscns pleurisepta (Conrad), a variety in which the abdomen becomes 

rounded at an early stage.

According to Mr. Stanton, there is in the National Museum a small 

collection of fossils obtained in the neighborhood of Eagle Pass by Mr. 

J. Owen. He collected .Exogyra costata at localities 1 mile southeast 

and 4 miles east of Eagle Pass. At the first locality he also collected 

a species of Volutornorpha and other Ripley forms.

Beds composed of brownish sandstone, with occasional beds of fossils, were found along the road to Laredo until, about 30 miles from 

Eagle Pass (about 26 miles in a straight line). The following is a list 

of the fossils collected, with their localities:

Fossils collected 5 miles southeast of Eagle Pass (locality No. 276).

Ostrea'cortex Conrad?, immature specimens. 

Area sp.

Fossils collected 14 1-2 miles southeast of Eagle Pass (locality No. 276). 

Ostrea cortex Conrad.

Fossils collected IS 1-2 miles southeast of Eagle Pass (locality No. 277).

Ostrea cortex Conrad.

Anomia sp., same as species from, locality No. 273.

Cardinm sp. Cf. C. eufalense Conrad.

Mactra sp. Cf. M. warreneana M. and H.

Pholadoinya n. sp.

Turritella sp., small casts.

Nautilus dekayi Morton.

Sphenodiscus pleurisepta (Conrad). Typical and abundant.

"The collection evidently belongs to the same subfauna which is 

more closely related to the Ripley than to any other. The facts that 

it is in beds that overlie those containing typical Ripley fossils, and 

that a considerable proportion of the species are peculiar to these beds, 

are strong indications that we may have here more recent Cretaceous 

beds than the latest Ripley beds of Mississippi, Alabama, and other 

portions of the Gulf Coast region." This idea has already been 

advanced by Mr. Durable. 1 (Stanton.)

i Bull.'Geol. Soc. America, Vol. Ill, 1892, pp. 219-230.
28 . BIO GRANDE COAL FIELDS OF TEXAS. [BULL. 164.

JMsumt of characters and thickness of the Eagle Pass formation.

Feet. 

Eacondido beds, composed of sandstones and clays, with many fossil if erous

horizons, exposed for 26 miles below Eagle Pass.......................... 2j 600

Coal series, as determined by artesian well bore, which begins in the upper- ' 

most bed .............................................................. 900

San Miguel beds, the lower 600 feet of the artesian well bore and the thickness of sandstone exposed in the hills north of the Carter ranch, 15 miles 

above Eagle Pass (200?) ................................................. 800

Total thickness of Eagle Pass formation.............................. 4, 300

RECONNAISSANCE FROM CLINE, UVALDE COUNTY, TO EAGLE PASS.

The road from Cline leads across the Anacacho Mountains to the 

Beasley ranch, some 10 miles to the south; thence southward to the 

crossing of the main Eagle Pass-Uvalde road over Chacon Creek. 

From this point the journey was made along the main public road to 

Eagle Pass.

The Anacacho formation will receive detailed consideration later. 

It suffices to say here that in the creek just south of Beasley's house 

this limestone has dipped beneath clays which initiate the Eagle Pass 

series.

The whole distance from the first crossing over Mula Creek, south of 

the Beasley ranch, to the third crossing over the same stream is a silt 

and gravel flat, with absolutely no bed-rock exposure. The gravel is 

chiefly flints. The vegetation consists of low, scraggly mesquite 

bushes, lignum vitse, and some cats-claw, occasional junco, and some 

tasajillo (Opuntia leptocaulis), with very little grass. The surface of 

the ground is glazed and 'checkered by small cracks.

From this crossing over Mula Creek to Chacon Creek the surface is 

composed entirely of silt and gravel. At the crossing over Chacon 

Creek the main Uvalde-Eagle Pass road is reached. On the southwest side of the road there is an outcrop, from beneath the silt and 

gravel, of brownish sandstone, in-which is an agglomerate of Ostrea 

cortex Conrad. 

Between Chacon Creek and Salado Creek the surface is covered by 

gravel and silt. About one-fourth of a mile north of Salado Creek is 

an outcrop of coarse-grained brown sandstone-. The following section 

was observed on the north side of the creek at the ford:

Section at ford on north si.de of Salado Creek.

Feet. 

3. Thinly laminated, .pinkish, purplish, and brown cross-bedded sands ........ 1-2

2. Yellow clay............................................................. 3-5

1. Hard, yellowish sandstone, containing many fossils, which are difficult to 

free from their matrix.
VAUGHAN.] RECONNAISSANCE FROM CLINE TO EAGLE PASs! 29

There is an oyster, probably 0. cortex, besides which Mr. Stanton 

lias identified the following fossils from the collection made at this 

place:

Liniopsis? sp. 

Gyrodes petrosa Morton. 

Strepsidura ripleyana Conrad. , 

Pyropsis sp.

These indicate, according to Stanton, the fauna of the Ripley and 

Navarro beds.

For about a mile after passing Salado Creek the surface is composed 

of residual sands, with occasional outcrops of yellowish sandstones. 

For the next half mile there are sands with some gravel embedded in 

them. For the next 5 miles the soil is usually argillaceous, or a mixture of sand and clay, and there is a considerable amount of gravel 

scattered over the surface. In ascending a small hill 5i miles 

beyond the Salado crossing many fossils were found in a hard layer 

of greenish sands, which overlies soft yellowish and greenish sands 

and clays. Mr. Stanton identified the following species from a collection made at this locality:

Trigonia sp., a small imperfect specimen related to T. eufalensis Gabb. 

Cardium sp., a form that is abundant in the Navarro beds at Corsicana, Texas. 

Veleda lintea Con.'? This also occurs at Corsicana. 

Turritella trilira Con. variety. 

Baculites ? sp., a crushed fragment.

Mr. Stanton remarks: "The fossils from this locality and those 

from 11£ miles north of Eagle Pass, near Burr's ranch, and 2 miles 

north of Eagle Pass are nearly all either identical with or closely 

related to species that occur in the K-ipley fauna of Mississippi and 

Alabama and in the uppermost Cretaceous beds of Navarro and Kaufman counties, Texas. This fauna has a vertical range of several hundred feet in Alabama."

Six and a half miles below the Salado crossing the foundation of the 

soil is a yellowish-brown clay. Gravel is scattered over the surface. 

It is chiefly flint, but there is also a considerable admixture of porphyry, showing that the gravel has been brought down by the Rio 

Grande.

Although there is not a continuous coating of gravel over the hills 

from this point (17 miles from the Eagle Pass court-house) to 

Eagle Pass, gravel occurs, in more or less disconnected patches, the 

whole distance. The rocks consist of alternations of yellowish flaggy 

sandstones and clays. From about 11^ to 11 miles north of Eagle 

Pass Evoogyra costata was found in considerable abundance in yellowish clays. These clays are both overlain and underlain by soft 

yello N sandstone. This clay bed, by aneroid barometer measurement, is 50 feet thick. The road runs approximately along the strike
30 EIO GEANDE COAL FIELDS OF TEXAS. [BOLL. 164.

/

of the rocks, and the stratigraphic position of the Exogyra costata 

clays and their associated sand beds seems to coincide with that of the 

sands and clays forming the top of the escarpment overlooking the Rio 

Grande Valley, 6£ miles north of Eagle Pass, i. e., the base of the 

Escondido formation. These beds occur considerably above the coalbearing horizons. About 2 miles from the court-house is a fossiliferous horizon in clays, a section of which gives the following:

Section 2 miles north of Eagle Pass court-house.

Feet. 

4. Hard brownish sandstone ledge, forming top of the escarpment.

3. Slope of soft yellowish sandstone, about.'................................ 20

2. Indurated fossiliferous layer............................................ £-1

1. Yellowish clay.

Mr. Stanton has determined the following from a collection of fossils 

made at this locality :

Cardium eufalense Conrad?

Mactra sp. Of. Mactra formosa M. and H.

Dentalium sp.

Natica sp. Occurs at Kaufman, Texas.

Turritella winchelli Shumard. Occurs at Corsicana, Texas.

Strepsidura ripleyana Conrad.

Undetermined volutoid? Cf. Ancilla cretacensis Conrad.

Volutomorpha sp. Cf. V. gabbi Whitefield.

Sphenodiscus pleurisepta (Conrad).

The conclusion to be drawn from these notes is that the whole of 

the rocks exposed from the crossing over Chacon Creek to Eagle Pass 

belong above the Eagle Pass coal and correspond approximately to the 

base of the Escondido formation.

RECONNAISSANCE FROM EAGLE PASS TO CARRIZO SPRINGS.

From Eagle Pass to Robert Thomson's house, 20 miles east of the city, 

th© bed rock presents the same character that it exhibited in going 

down the Rio Grande to Santo Tomas. It consists of sandstone and 

clays; for the last 8 miles before reaching Thomson's ranch clays prevail. The tops of the hills are generally capped by gravels, the sandstone and clays being exposed in the creek valleys and along the 

slopes.

Four miles east of Thomson's, on the 'road to Carrizo Springs, a 

specimen of Sphenodiscus pleurisepta was found in yellow clays.

To within 9 miles east of the Thomson place dirty, dark ocher-colored 

clays form for the most part the surface of the ground; there is some 

sand in the draws, and gravels occur on the high ridges. No sharp line 

between the Cretaceous and Eocene was discovered, and no fossils were 

found in the transition beds.

At about 9 miles east of Thomson's ranch and 16 miles west of Carrizo. 

Springs, a ckange of geological formation was noticed. The clays above
VAUOHAN.] ANACAOHO FOEMATION". 31

described are here succeeded by fine-grained sandstones containing 

some mica. There are bands of red iron ore and many bits of hematite. 

The flora consists mostly of Opuntia, lignum vitae, some guajillo, some 

rhamnaceous shrubs, and mesquite. There was no grass, the ground 

betA\reen the cactus and the shrubs being barren.

Although it can not be affirmed with certainty, it is quite probable 

that this change in the character of the rocks marks the boundary 

between the Cretaceous and the Eocene. .

STUDIES ALONG TURKEY CREEK AND THE NUECES RIVER, THE FRIO 

AND SABINAL RIVERS, BRACKETT AND UVALDE QUADRANGLES (EASTERN KINNEY COUNTY AND UVALDE COUNTY).

The sections along these streams are described in the discussions of 

the formations.

ANACACHO FORMATION.

This formation was defined by Hill and Vaughan in the Geology of 

the Edwards Plateau and Rio Grande Plain, etc. 1 It is the stratigraphic equivalent of the Upson clays of the Rio Grande section, and 

of the Taylor (Exogyra pond&rosa) marls of central Texas. It overlies 

the Austin chalk, and is in turn overlain by sandy limestones, sandstones, and clays. Its component rocks are either hard or soft yellowish limestones or yellow marls, the calcareous constituents being 

in excess of the argillaceous.

The following section is taken from the report cited above:

Section of the Anacacho Mountains, Kinney County.

II. Anacacho formation: ' Feet.

8. Scarp-making rock, forming the top of the hill. It is a hard, yellow, 

subcrystalline limestone. In the top a species of Alectryonia was found. 

About 30 feet below the top, great numbers of Gryphxa vesicularis occur, 

firmly embedded .....................'............................. 60

7. Softer limestone: b, Soft, yellow, marly limestone, containing a large 

species of Cardium, 50 feet; a, Soft, white, chalky limestone, containing 

a species of Turritella with three prominent revolving strise on each 

whorl (T. trilira Con.?), 30 feet; total...........................'.... 80

6. Hard limestone ledges. The upper 30 feet is brownish, and contains 

great numbers of Exogyra, ponderosa firmly embedded near the top. The 

next lower 20 feet is a yellowish granular limestone with glauconitic 

specks. This bed forms a platform on the east end of the Anacacho.. 70

5. Ledges of yellow, ferruginous, not very hard, subcrystalline limestone,

forming the lower scarp on the east end of the hill ................... 30

4. Slope composed of marly limestone in the upper part, the lower portion 

yellow marls with fragments of a very large and coarsely corrugated 

Inoceramus ....................................................... 20

3. Yellowish limestone, weathering into nodular chunks, iron-stained along 

the weathering cracks. Contains some poorly preserved fossils Trigonia (?), Mactra, and a finely-ribbed Lima .......................'.. 10

Eighteenth Ann. Kept. U..S. Geol. Survey, Part II, 1898, pp. 240, 241.
EIO GRAKDE COAL FIELDS OF TEXAS. lui.rLL.164.

II. Anacacho formation Continued. Feet. 

2. Soft material containing fragments of a very large Inbceramus.......... 5

1. Thin, very hard, brown, siliceous ledge............................. 3 or 4

Total Anacacho beds........................................... i. 279

1. Austin chalk:

3. Hard brownish limestone, containing many Gryphxa aucella ........... 5

2. Hard chalky limestone............................................... 10

1. Unexposed to bottom of arroyo. .................................... 20

Total Austin chalk exposed....................................... 35

Total Anacacho beds............................................. 279

Total here exposed. .............................................. 314

The measurements were made with an aneroid barometer and must be regarded 

as only approximately correct.

The deposit of asphalt at the Lithocarbon Rubber Company's mine is in the 

Anacacho limestone. The asphalt-bearing horizon corresponds with the upper part 

of No. 6, above.

The following is a compilation from a large number of sections 

made along Turkey Creek, beginning at Cline Mountain, in the Brackett quadrangle, and extending to 

Wagon Top Butte, in the Uvalde 

quadrangle.

___ X

Compilation of sections 

Creek.

along

Feet.

FIG. 4. Section of the Anacacho Mountains, Kin. 

ney County.

20. Hard gray limestone. This limestone is coarsely granular, loose 

textured, and possesses a very 

rough, honeycombed, weathered surface. It contains anundetermined species of Eadiolites or Sphaerulites........ 10

19. Thinly laminated, hard or marly

limestone-.................. 20

18. Ledges of gray limestone, with 

honeycombed surface, but not 

so hard as the uppermost limestone. This bed is not well 

exposed, so'that its detail could 

not be determined ........... 30

17. Hard, dark-brown, granular

limestone-.................. 3

](>. Light-colored, yellowish, granular limestone in hard, thick 

ledges. This bed contains 

specimens of a large Exogyra 

and a Eadiolite; also some 

pebbles of white and yellow 

quartz..................... ................. 7

15. Thinly bedded limestone, becoming a thinly laminated, firm, calcareous shale. 15

14. Laminated yellow calcareous marl.. ............... ^...................... 50
VAUGHAN.] ANAOACHO FORMATION. 33

Feet. 

13. Coarsely crystalline limestone, in thick ledges, containing a species of Kadiolite.................................................................. 15

12. Hard limestone ledge, containing small scattered calcite crystals and shell

fragments in a brown matrix .......................................... 10

11. Coarsely crystalline yellowish-gray limestone............................. 15

10. Soft limestone .°......................................................... 20

9. Scarp-forming limestone, several alternations of harder and softer beds about 

the base.............................................................. 30

8. Hard limestone with smallGryphsea ..................................... 10

7. Soft limestone.......................................................... 20

6. Soft limestone containing Trigonia sp..................................... 10

5. Thick ledge of yellow limestone ......................................... 10

4. Softer, more shaly limestone ............................................ 20

3. Thick ledge of granular, argillaceous, ferruginous limestone ............... 5

2. Softer, rather marly material............................................ 15

1. Ledge of limestone resembling No. 3..................................... 5

Total thickness....................................................... 320

Base of Anacacho formation and top of the Austin chalk.

The foregoing section must be regarded as only an approximation. 

Evidently there is considerable variation in the lithologic characters 

of the sections,' frequently making it difficult to correlate from one 

section to another. The sections were, for the most part, measured 

with an aneroid barometer, and although it was attempted to check 

them by the height of the hills as given on the topographic maps, 

absolute exactness could not be expected.

A carefully measured section along the Sabinal River was not 

obtained, but from a study frxmi several bluffs, and from several well 

bqrings, the general characters of the equivalent beds were discovered, 

and an estimate of thickness was made. The beds here are intermediate in character between the typically developed Anacacho formation and the Taylor marls. There are beds of limestone showing the 

same characters as the typical Anacacho, and also rather thick beds of 

yellow clay of the same character as the Taylor marls. There is more 

clay than in the vicinity of the Anacacho Mountains, and more limestone than in the central Texas region. These beds near Sabinal are 

considerably over 300 feet in thickness, probably 400 or more feet.

EAGLE PASS FORMATION IN BKACKETT AND UVALDE QUADRANGLES.

In the Uvalde quadrangle, between Turkey Creek and the Nueces 

River, the Anacacho limestone is overlain by a brown arenaceous limestone which grades into brown sandstones. 

Bull. 164 3
34 ' EIO GKANDE COAL FIELDS OF TEXAS. [BULL. 164.

'Section at, Asp1i,aU Falls, Nuewx River. ' Feet.

10. Flint gravel, lower rocks not exposed ................................... 8

9. Coarse-grained, laminated, and cross-bedded yellow sandstone............ ' 2

8. Soft yellow sandstone and 'clay ......................................... 25

7. Ostrea cortex embedded in clay and consolidated to form a firm ledge...... 2

6. Laminated, sandy, yellow clays. ......................... ^............. 3%

5. Soft ledge, composed- largely of fragments of oyster shells ................ 1

4. Soft, laminated, sandy, yellow clays .................................... 3

3. Soft, fine-grained sandstone, frequently beautifully cross-bedded and containing some asphalt....................:............................ 10

2. Asphalt-bearing sandstone ...................^......................... 5

1. Bluish clays to water's edge............................................ 2

10, Pleistocene. 

8-9, Eocene? 

1-7, Cretaceous.

The area occupied by these sandstones and clays up to the supposed 

base of the Eocene is very small, being only a mile or two wide, and 

the writer doubts that their maximum thickness exceeds 100 feet. 

Along the Frio River they are exposed from place to place from 

1 to 2 miles below Engelrnann's ranch. About 2 miles, measured in a 

straight line, below that ranch they dip beneath the Eocene sandstones 

and clays.

VARIATIONS IN CHARACTER OF THE FORMATIONS IN THE DIFFERENT

SECTIONS.

. There is very little variation in the formation below the Upson 

clays Anacacho formation. The Lower Cretaceous is practically the 

same in the Uvalde and Brackett quadrangles and westward to L}el 

Rio. This is also true of the Eagle Ford formation and the Austin 

chalk, but above the latter the variation is great.

Anacacho formation and Upson days. The equivalent of these formations in central Texas is, as already stated, the Taylor marls. In the 

vicinity of Austin these marls are calcareous clays, blue when fresh, 

but oxidizing yellow, and are about 540 feet thick. 1 In the vicinity of 

Sabinal clays resembling the Taylor marls and containing the same 

fossils are exposed along Sabinal River above the town, and have been 

penetrated by well borings. Here there are numerous thick beds of 

yellowish limestone interstratified with the clays. When the Anacacho 

Mountains in the Brackett quadrangle are reached, the clay beds have 

either entirely disappeared or become .very insignificant. Along the 

Rio Grande the equivalent Upson clays contain, so far as known, no 

limestone beds, but are composed entirely of greenish or bluish clays 

which oxidize yellow. These data, show that the Anacacho limestone 

is a purely local development. It 'is principally an organic limestone, 

produced by a great luxuriance of testaceous organisms, chiefly rnoli Hill and Vaughan: Eighteenth Ann. Kept. U. S. Geol. Survey, Part II, 1898, p. 240.
VAUGHAN.] BELATION OF CliETACEOUS TO EOCENE. 35

lusks. The causes that have brought about the conditions favorable 

for their growth are not known to the writer.

Eagle Pass formation, These beds have been shown to possess a 

total thickness of over 4,000 feet along the Rio Grande. They thin 

very rapidly to the north, so that the total thickness exposed along 

the Nueces River, in the Uvalde quadrangle, is only 100 or 200 feet. 

How much of the formation is buried by the Eocene overlap can not 

at present be determined, but the decrease in thickness is enormous, 

as is shown by the fact that the thickness below the lowest Oslrea 

cortex horizon, near Eagle Pass, is some 1,700 feet, while below the 

same horizon on the Nueces it is probably not more than 100 feet.

These beds are known to be thicker farther to the north than they 

are along the Nueces River, but how much they are influenced by the 

Eocene overlap is unknown. These facts reveal an extremely interesting problem the effect of the Eocene overlap, in regard to which 

much more data are needed before the problem can be satisfactorily 

solved.

RELATION OF THE CKETACEOUS TO THE EOCENE.

In order to avoid repetition the details of the basal Eocene will not 

be described here. They are discussed further on, in the description 

of the Eocene sections.

Here general statements only will be made.

Rio Grande section. As has been pointed out by White, Penrose, 

and t)urnble, there is no sharp lithologic line between the Cretaceous and the Eocene. The contact between the two series has not 

been discovered. The principal result of the writer's work on the Rio 

Grande was in proving the existence of Eocene fossils some 3 or 4 

miles above the Webb-Maverick county line, 6 or 7 miles above 

where Penrose and Dumble first- found such fossils. The fossils 

obtained here are typical Lower Eocene, and there has been discovered 

in this region no greater indication of the commingling of faunas than 

has been found in Alabama or other States, where it has been distinctly shown that an erosion interval occurred between the two series. 3 

Because of these faunal relations, it is the writer's opinion that the 

Cretaceous and Eocene series here were separated by an erosion inter-, 

val, as is known to be the case elsewhere, and it is quite probable that 

more extended investigations will subsequently establish the exact 

contact, though this may not be possible-because of the limited number of fossils obtainable and the lack of good exposures.

Bet/ween Eagle Pass and Carrizo Springs. The probable contact 

between the Eagle Pass formation and the Eocene has already been 

described (see p. 30). No actual contact was observed. The probable 

contact is 9 miles east of the Robert Thomson ranch, where the Upper

1 Harris: Bull. Am. Pal., No. 4,1896, p. 28.
36 EIO GKANDE COAL FIELDS OF TEXAS. [BULL. 164.

Cretaceous clays end and sandstones of the Carrizo Springs type are 

first initiated.

Along the Nueces River. Here, again, there is indefiniteness, due to 

the similar lithologic character of the rocks and the dearth of fossils. 

A detailed section across the contact is given on p. 34 in the discussion 

of the Eagle Pass formation. The base of the Eocene is placed provisionally at the top of the Ostrea cortex ledge, because, (1) on the 

Frio River, 19 miles farther east, a ledge of these oysters is undoubtedly the summit of the Cretaceous; (2) a short distance below the 

exposure of this ledge on the river, andstratigraphically above it, a few 

plant remains were found which Professor Knowlton considers probably Eocene; (3) the strata above this oyster ledge on the Nueces are 

very similar to strata on the Frio River, known with certainty to be 

Eocene, or are lithologically identical with those strata. The proof 

that the writer has located exactly the Eocene-Cretaceous contact on 

the Nueces is not absolute, but the evidence in favW of the location is 

strong, and it is doubtful whether the contact will be determined with 

greater exactness, unless it subsequently becomes possible to make 

more extended use of the plant remains, which are few and imperfectly preserved.

Along the Frio River. About 2 miles, in a straight line, below the 

Engelinann ranch and about a half mile above Myrick's lower apiary, 

a definite clear-cut-contact is revealed. The section exposed is described 

in detail on p. 51. Evidence of erosion exists in the pebbles of the 

basal Eocene, but this evidence is not very strong, because of the general lithologic constitution of the rocks (shallow-water sandstones and 

clays), and because local erosion unconformities or pebble beds might 

exist almost anywhere. The faunal break is as sharp as a knife's edge. 

As the Eocene rests on a ledge of tfte Cretaceous Ostrea cortex, to be 

sure some Eocene fossils are mixed with the oysters along the basal contact, but no Eocene species was found below that ledge, and no Cretaceous species was found above the basal contact. These data prove 

absolutely that there must have been a break in the sequence of sedimentation long enough to permit a complete f aunal revolution.

Although fragmentary, these data sustain the conclusion that there 

are in the Rio Grande region of Texas no transition beds between the 

Cretaceous and the Eocene. The respective faunas are absolutely distinct, with as complete a break between them as is known anywhere. 

The difficulty in differentiating Cretaceous and Eocene rocks lies in the 

similar lithologic constitution of the two series.
VAUGHAN.] DESCRIPTIVE GEOLOGY. 3V

TERTIARY. 

EOCENE.

Near India ranch, about 26 miles, in a straight line, bel'ow Eagle Pass, 

the lithologic character of the rocks changes to a coarsely crystalline 

sandstone of a yellowish or brownish color. The best exposures of this 

sandstone are seen near Moro ranch well, at Chupadero ranch, and 12f 

miles south of Uvalde on the road to Batesville. The grains are small 

quartz crystals, which are often cemented together by iron oxide.

RIO GKANDE SECTION.

In the arroyo immediately east of India ranch is a clay containing 

calcareous concretions. This clay lies below the sandstone to be next 

described.

From India ranch to San Ambrosia Creek the road to Laredo passes 

over numerous exposures of ripple-marked brown sandstone, which 

disintegrates rapidly and forms very poor roads. Between San Ambrosia and San Lorenzo creeks, as there is no covering of more recent 

deposits, loose sands, derived from the disintegration of the sandstone, 

constitute the surface. The best exposures of this sandstone are at 

Chupadero ranch. Here it contains numerous fantastically shaped 

concretions, and peculiar sandstone pillars are formed by erosion and 

weathering. When unweathered the sandstone is gray, but upon disintegration it forms coarse, loose, brown crystalline sands. Its thickness, so far as ascertained, is 150 feet. (See fig. 5, p. 53.) It is underlain b}7 clays, and is a well-defined lithologic horizon, apparently what 

Owen designated the Carrizo sands. 1

At Chupadero ranch a well sunk into this sandstone yields a permanent supply of water, which is, however, never more than a few feet 

in depth.

Between Chupadero Creek and San Ambrosia Creek flint gravel forms 

the capping of the divide.

West of San Ambrosia Creek, going down to the Rio Grande from 

the divide, dirty, dark-brownish or yellow clays are seen. These pass 

beneath the sandstone exposed around Chupadero ranch. The bluff 

on Rio Grande 1 mile above the mouth of San Ambrosia Creek is 40 

to 50 feet high and is capped by sandstone; the base is of laminated 

sands and clay. Three and one-half miles above °the mouth of this 

creek the banks of the river are composed of sandstone and thinly 

bedded lignitic sands. Specimens of Venwicardia pl<micosta Lam. 

were found in a piece of sandstone from this locality, and a specimen 

of Ostrea crenulimwrginata Gabb was picked up near by. These would 

indicate that the horizon of the beds here exposed is Midwayan Eocene.

1 First Kept, of Progress of Texas C4eol. Survey, 1889, pp. 70-78.
38 EIO GKANDE COAL FIELDS OF TEXAS. [BUM,. 164.

Four and one-half miles above the mouth of San Ambrosia Creek 

the following section was observed:

Sqption 4 1-% miles above mouth of San Ambrosia Creek.

Feet.

5. Fluvial silt, forming the top of the bluff. 

4. Ledges of soft, yellowish or whitish sandstone.......................... 7 to 8

3. Laminated sandy clays, streaks of sand and streaks of clay. The colors are

brown, yellow, and purple; the last being caused by carbonaceous matter. 3 

2. Soft sand bed of a light, grayish-purple color, with darkish sulphur-yellow

patches........ .................................................. 3

1. Irregularly laminated soft sands, light grayish-green in color and containing

much carbonaceous matter........................................... 4

Total.............................................................. 18

There is a considerable amount of soft, very pure sand rock along 

this part of the river. In No. 4 of the foregoing section the ledges 

sometimes change to thinly laminated sands along the face of a single 

exposure, as was observed in one instance.

No. 1 of the section is quite thick, changing toward the base into 

clays of purplish color, due to the presence of carbonaceous matter. 

These beds are identical, in external appearance, with the lignitif erous 

Claiborne beds of Louisiana. They are probably 100 feet thick. 

It is at about the point where the foregoing section was made that 

the southern fence of the India ranch pasture is reached. This fence is, 

according to the statements of a colored cowboy, between three-fourths 

of arnile and amileabove the Webb-Maverick county line. Just beyond 

this fence, within the India ranch pasture, hematitic concretions containing V&n&ricardia alticostata Conrad and a species of G-lycymeris 

(Pectunaulus) of the type of G. staminea (Conrad), were found in the 

clays. A little farther up the river was a large mass of sandstone resting on the clays and containing beautiful specimens of Turritella mwtoni. The sandstone was so hard that no attempt was made to get the 

shells out.

From H to 2 miles above the fence referred to the thinly bedded 

sands and clays are seen to be underlain by thinly bedded sands, passing downward into thin ledges of soft sandstone.

This has carried the Eocene to a point at least 2 to 3 miles above the 

Webb-Maverick county line. The horizon of the Eocene is Midwayan. 

The following five species of fossils were collected:

Turritella mortbni Conrad.

Ostrea crenulimarginata Gabb. »

Glycymeris (Pectunculus) sp. indet.

Venericardia planicosta Lam.

Venericardia alticostata Conrad.

Harris has identified, from the Dumble-Penrose collection made 3 

miles below the Webb-Maverick county line, fossils that are probably 

'Midwayan, Lower Eocene, 1 but the writer has been unable to obtain a

1 Bumble: Jour, of Geol., Vol. II, No. 6, 1894, p. 550; Harris: Bull. Am. Pal., Vol. I, 1896, p. 127 

(No. 4,13).
VAUGHAN.] EOCENE FOEMATIONS. 39

list of the species found there. Harris (op. cit.,loc. cit.) says: * * * 

"we should note the peculiar fauna, Midway, in part, at least, found 

by Dr. White 18 miles southeast of Eagle Pass. It consists of CuculIcea macrodonta (perhaps saffardi], Pectunculus, Venericardia [pi. 5, 

fig'- £] 'The shelly matter of these species is completely crystallized.' 

'The matrix was evidently a calcareous light sand or sandstone.' 

Harris, Ann. Kept. Geol. SUIT. Ark., 1892, Vol. II."

The actual Cretaceous-Eocene contact has not been located along the 

Rio Grande.

It has been reported that many fossil oysters occur on the high 

divide Ipetween the Chupadero and India ranches, west of San Ambrosia 

Creek. The writer was unable to make a search for the locality, and 

did not learn of anyone who had collected specimens from there. He 

is of the opinion that the section referred to is a bed of Ostrea cren.ulimwgwiata Gabb, as this species occurs at several places in the basal 

Eocene of Texas.

The following section 1 of Webb bluff, on the Rio Grande, 3 milQS 

below the north line of Webb County and southeast of India ranch, 

is from Pen rose:

Section of Webb bhiff, on Rio Grande.

Feet.

3. Fine, white, indurated, sandy clay, with dark streaks and specks of lignitic 

matter................................................................ 30

2. Greensand marl, with many Tertiary fossils, nodules of carbonate of lime

containing glauconitic specks. ........................._................. 7-8

1. Stiff, plastic, bluish-black clay, jointed, containing specks of mica.......... 10

Dip of strata, 3° SE.

Bumble subsequently published the same section 2 and stated that it 

is capped by gravel. Beds Nos. 2 and 3 are the same as the Webb 

bluff beds of the section by Dumble.

The coarse-grained sandstone seen around Chupadero ranch is overlain near there by a finer-grained laminated sandstone. At Guajolote 

ranch the coarse-grained sandstone has disappeared, and we have the 

following section:

Section at Guajolote ranch,.

Ft. in.

6. Gravel capping (Pleistocene). 

5. Micaceous shale........................................................ 10 0

4. Ledge of brownish-green micaceous sandstone............................ 2 0

3. Laminated micaceous sandstone ........................................ 8 0

2. Seam of ferruginous concretions. ........................................ 0 3

1. Massive yellow micaceous sandstone, thickness unknown.

'First Ann. Kept. Geol. Survey of Texas, 1890, p, 41.

8 Bull. Geol. Soc. America, Vol III, 1892, p. 228; also, Bumble's Report on brown coal and lignite of 

Texas, Geol. Survey of Texas. 1892, p. 137. In the latter report it is stated that the lowest stratum 

is Cretaceous. '
40 EIO GRANDE COAL FIELDS OF TEXAS. [BULL. 164.

On the hilltops to the southeast of the Guajolote ranch clays occur 

above the micaceous sandstones. Ten miles, by road, southeast of 

this ranch, the following section was observed:

Section 10 miles southeast of Guajolote ranch.

Feet.

2. Shaly sandstone, fine grained, laminated, ripple marked in the upper part, and 

containing obscure or poorly-preserved leaf impressipns................... 20

1. Thinly laminated sandy clay shale......................................... 15

From No. 2 several specimens of leaf impressions were obtained and 

submitted to Professor Knowlton for determination. He makes the 

following notes on them:

There is one fine leaf in this lot, but it unfortunately appears to be new. It is a 

fine, narrow, toothed Celastrus. There is also a small fragment of a palm leaf, but it 

lacks both apex and point of attachment, and is thus deprived of all characters. 

There are two or three other fragments of leaves and a large number of stems, possibly of monocotyledons.

The new species of Celastrus appears to resemble most closely a species (C. rectiwerwsWard) from the Fort Union (Eocene) of Montana. The palm has some resemblance to a Denver species, but as it lacks the essential characters it is impossible .to 

identify it.

One and an eighth mile from the foregoing locality the first outcrop 

of the Eocene lignite was seen. The rocks in the vicinity consist of 

micaceous sandstones and clay shales. The dip is about 1° south of 

east.

From the last-mentioned locality to Santo Tomas the lithologic characters of the rocks are about the same, i. e., they consist of interbedded 

micaceous sandstones, which vary much in hardness and in color, and 

of clays or clay shales.

About 8 miles before reaching Palafox poor remains of marine fossils 

were collected in a micaceous sandstone.

Section of butte 4 miles north of Palaf ox.

4. Gravel capping (Uvalde formation). . Feet.

3. Red or brown sandstone .................................................. 45

2. Flaggy sandstone......................................................... 3

1. Crumbling shales......................................................... 27

Two and a half miles northeast of Palafox there is an exposure of 

lignite.

The following are records of two prospect drills kindly furnished 

by Mr. D. D. Davis, superintendent of the Cannel Coal Company, 

which has its mines near Santo Tomas.
VXXJGHAN.j EOCENE FOEMATIONS. 41

Prospect drill No. %, by Cannel Coal Company, northeast of Carbon, about 3 miles southeast

of Santo Tomas.

Depth.

Ft. in. Ft. in. 

00-50

50-90

9 0- 10 6

10 6-19 0

19 0- 21 0

21 0-44 0

44 0- 45 4

45 4-46 0

46 0-56 0

56 0-63 0

63 0- 72 0

72 0- 75 0

75 0-83 0

83 0-90 0 

90 0-91 0

91 0-95 0

95 0-109 6

109 6-110 11

110 11-112 10

112 10-114 10

114 10-116 5

116 5-130 0

130 0-135 0 -

135 0-139 0

139 0-141 0

14J 0-156 0

156 0-160 0

160 0-164 0

164 0-167 0

167 0-206 0

206 0-209 0

209 0-225 0

225 0-227 0

227 0-230 0

230 0-240 0

240 0-269 0

269 0-271 0

271 0-281 0

281 0-320 0

Material.

Clay and sandstone. .........................

Gray shale. .................................

Brown shale ................................

Coal........................................

White sandstone .............................

Gray shale. .................................

Sandstone ..................................

Mixed shale and sandstone, marine rnollusks . - 

Limestone (fossil shells) .....................

Slate.......................................

Sandstone ..................................

Slate.......................................

Coal .......1

Clay shale . . >San Pedro coal seana ............

Coal........J

Sandstone ..................................

Slate.......................................

Sandstone ..................................

Slate .......................................

Slate.......................................

Slate.......................................

Sandstone ..................................

Slate.......................................

Clay .......................................

Slate.......................................

Sandstone ......'............................

Shale.......................................

Sandstone ..................................

Shale.......................................

Tough shale ................. __ ..........

Thickness.

Ft. in. 

5 0

4 0

1 6

8 6 ,

2 0

23 0 .

1 4

0 8

10 0

7 0

9 0

3 0

8 0

7 0 

1 0

4 0

14 6

1 5

1 11

2 0

1 7

13 7

5 0

4 0

2 0

15 0

4 0

4 0

3 0

39 0

3 0

16 0

2 0

3 0

10 0

29 0

2 0

10 0

39 0
42 EIO GBAKDE COAL FIELDS'OF TEXAS. [BULL. 1C4.

Prospect drill No. 2, by Cannel Coal Company, northeast of Carbon, about 8 miles south- 

» east of Santo Tomas Continued.

Depth.

Ft. in. Ft. in. 

320 0-322 0

322 0-328 0

328 0-340 0

340 0-356 0

356 0-400 0

400 0-404 0

404 0-418 0

418 0-424 0

424 0-435 0

435 0-446 0

446 0^47 0

447 0-456 0

456 0-461 0

461 0-464 0

464 0-476 0

476 0-482 0

482 0-485 0

485 0-490 0

490 0-500 0

Material.

Shale.............................:.........

Shale...............................:.......

Sandstone ..................-.--.....-..-.--

Shale.......................................

Sandstone ..................................

Slate...'....................................

Sandstone ..................................

Shale.......................................

Limestone ..................................

Shale.......:.................. .....----.

Shale.......................................

Sandstone ...................................

Shale. .............. ..... ................

Sandstone ..................................

Shale.......................................

Sandstone .............. ........t... ........

Thickness.

Ft. in. 

2 0

6 0

12 0

16 0

44 0

4 0

14 0

6 0

11 0

11 0

1 0

9 0

5 0

3 0

12 0

6 0

3 0

5 0

10 0

Mr. Davis states that the lower sandstones were not very coarse nor 

were they crystalline. The elevation at the surface, where this drill 

was sunk, is about 530 feet.

Prospect drill No. 6, at Pilot ranch, 25 miles west of north from Santo Tomas, and 3 1-2

miles from the Rio Grandc.

Depth.

Ft. in. Ft. 

0 0-10

10 0-12

12 0-28

28 0-44

44 0-46

46 0-68

68 0-74

74 0-74

74 8-75

75 0-80

in. 

0

0

0

0

0

0

0

8

0

0

Material.

Soil........................................

Gravel .....................................

Yellow shale clay ...........................

Blue shale clay .............................

Clayey sandstone ......... . . . . . i . . ..........

Blue shale clay .............................

Blue shale clay .............................

Bony coal ..................................

Brown shale clay ...........................

Thickness.

Ft. in. 

10 0

2 0

16 0

16 0

2 0

22 0

6 0

0 8

0 4

5 0
VAUGHAN.] EOCENE FORMATIONS. 43

Prospect drill No. 6, at Pilot ranch, 25 miles west of north from Santo Tomas, and 3 1- 

miles from the Rio Grande Continued.

Depth.

Ft. in. Ft. in. 

80 0- 84 0 

84 0- 84 10 

84 1.0- 85 2 

85 2- 90 0 

90 0-91 11 

-91 11- 92 3 

92 3- 94 0 

94 0-107 0 

107 0-117 0 

117 0-117 6 

117 6-118 0 

118 0-119 0 

119 0-125 .0 

.1.25 0-131 0 

131 0-145 0 

145 0-149 0 

149 0-153 0 

153 0-156 0 

1.56 0-168 0 

1.68 0-174 0 

174 0-176 0 

176 0-184 0 

184 0-208 0 

208 0-208 6 

208 6-210 0 

210 0 215 0

215 0-216 3 

216 3-220 0 

220 0-220 9 

220 9-221 0 

221 0-227 2 

227 2-228 10 

228 10-229 0 

229 0-230 8 

230 8 232 0

232 0-232 6 

232 6-236 6 

236 6-236 8 

236 8-237 5

Material.

o

Coal ............

White sandstone .

Coal.............

Bone ............

Light-brown shale 

Tough shale ......

Shale clay ........

Bone .............

Bone .............

Shale clay ........

Sandstone --...-..

Clayey sandstone. .

Clay .............

Shale clay ........

Sandstone ........

Tough shale ......

Bony coal ........

Clay .............

Brown sandstone. .

Bony coal ........

Brown clayey sand 

Coal..............

Brown sandstone. .

Coal..............

Striped brown sane

Bone .............

Bone .............

Coal..............

Thickness.

Ft. in. 

4 0 

0 10 

0 4 

4 10 

1 11 

0 4 

1 9 

13 0 

10 0 

0 6 

0 6 

1 0 

6 0 

6 0 

14 0 

4 0 

4 0 

3 0 

12 0 

6 0 

2 0 

8 0 

24 0 

0 6 

1 6 

5 0 

1 3 

3 9 

0 9 

0 3 

6 2. 

1 8 

0 2 

1 8 

1 4 

0 6 

4 0 

0 2 

0 9
44 BIO GBAtfDE COAL FIELDS OF TEXAS. [BULL. 164.

Prospect drill No. 6, at Pilot ranch, 25 miles west of north from Santo Tomas, and S 1-2 

miles from the Rio Grande Continued.

Depth.

Ft. in. R. in. 

237 5-238 0

238 0-244 0

244 0-246 0

246 0-254 0

254 0-255 0

255 0-262 0

262 0-268 0

Material.

o

Bone .......................................

Sandstone ..................................

Brown shale ................................

«

Blue shale clay ...... 1 .......................

Sandstone ...........i..... .................

Blue shale clay. .............................

Thickness.

Ft.' in. 

0 7

6 0

2 0

8 0

1 0

7 0

6 0

Section at the Santo Tomas coal mine (Rio Grande Coal and Irrigation Company) - 1

Ft. in.

7. Carbonaceous shale roof; shale soft and requires considerable timbering.

6. Good coal.............................................................. 0 14

5. Bone ................................................................. 0 4

4. Good coal............................................................. 0 14

3. Bone.-.................-...-..-.......-.-....----------.-----..-.----. 0 6

2. Clay.................................................................. 7 0

1. Sandstone.

(See fig. 6, p. 54.)

The Cannel Coal Company's mine is about 3 miles below San to Tomas. 

Through the courtesy of Mr. D. D. Davis, the manager, the writer 

was enabled to" make the following section:

Section at mine of Cannel Coal Company, 3 miles below Santo Tomas.

Ft. in.

8. Clay slate or sandstone-..--.......................................... 0 14

7. Carbonaceous shale .................................................. 0 \

6. Good coal........................................................... 2 0

5. Bone......--.....-..----------------.....--.---...--..-..-.......-- 0 15

4. Clay................................................................ 2 0

3. Lower bench:

c. Good coal ........................................................ 0 6

b. Bone .......'.................................................... 0 2

a. Good coal. -.--.....-......----_._....-........-....--.....-..... 0 11

2. Carbonaceous shale ................................................... 0 3

1. Sandstone..-..-.-.....---......-------..-.--.---.--...--.....---.-.- 14 0

In this mine there is a small fault, and along the plane of the faulting there is a small sandstone dike.

From prospect drill No. 2, between 83 and 90 feet, Mr. D. D. Davis 

had obtained and preserved some fossil rnollusks, which he presented 

to the Survey. They were referred to Prof. G. D. Harris for determination. He says they belong to an undescribed fuana, and has not 

yet furnished any identifications.

1 Mr. D. J. Koy, manager of this mine, rendered much assistance and showed us many courtesies 

while we were in Santo Tomas. It was through his kindness that we were enabled to examine the 

mine.
VAUGHAN.] EOCENE FOKMATIONS. ' 45

Dr. C. A. White has collected some fossils near Santo Tomas, but 

they have not been determined. These specimens, also those from the 

coal shaft, are poorly preserved.

The dip at Santo Tomas, according to information furnished by Mr. 

Davis and based upon mine workings, is 2° N. 40° E.

From the sandstone which immediately overlies the coal Mr. Davis 

had collected several fossil leaves, which he presented to us. Professor 

Knowlton has examined them, and finds a new species of Juglans, and 

another species which could not be determined.

From the clays just' above the coal (locality No. 280) Mr. Stanton 

collected some leaves and a Unio. The leaves were too poor for identification. Professor Knowlton states that one looks like a Ficus; he is 

also of the opinion that the plants from Santo Tomas have a Laramie 

facies, but does not feel justified in expressing an opinion as to whether 

they are from the upper or the lower Laramie.

The following is a re'sume' of the section of the Eocene based on 

observations and the data accumulated:

Resume of section of Eocene.

Feet. 

5. The coal beds and the clays and sandstone immediately overlying them were

the highest beds seen. Between the two coal seams is a bed of fossils not 

yet determined........................................................ 190

4. Below the coal beds is a series of alternations of clay, shales, and sandstones

of a thickness of at least........?.............................'......... 400

3. A series of fine-grained micaceous sandstone.............'.................. 300

2. The coarsely crystalline Carrizo sandstone, with a thickness of at least...... 150

1. Bluish clays ascertained by a well boring, below which are more sandstones 

and clays.

The fossils reported by Pen rose l from Webb bluff probably occur 

below the Carrizo sandstone.

It is evident that the coarse sandstone seen at and near Chupadero 

ranch has not been reached in the prospect drill at Carbon, near 

Santo Tomas. It is difficult to correlate the records of the drill at 

Pilot ranch with the Santo Tomas section. Lithologically the section 

resembles very much the coal-bearing portion of the Santo Tomas 

section. In the Pilot ranch drill hole the lower sandstone has not 

been reached.

The disturbance in the dip at Santo Tomas, together with the 

extreme similarity in lithologic character of the beds, introduces such 

complications that reliable estimates of the thickness of the beds and 

the determination of the number and relative position of the coal 

seams can not be made until the area has been studied in detail.

The following is taken from Penrose's description of the section 

along the Rio Grande from Webb bluff to Laredo. 2 The section of 

Webb 'bluff has already been given.

1 First Ann. Kept. Geol. Survey of Texas, 1890, p. 41.

" First Ann. Kept. Geol. Survey of Texas, pp. 42 and 43; see also Bumble's Report on the brown 

coal and lignite of Texas: Geol. Surv. of Texas, 1892, pp. 137-139.
46 KIO GRANDE COAL FIELDS OF TEXAS. [BULL. 164.

A quarter of a mile below (i. e., Webb bluff) is a bluff 50 feet high of indurated 

sandy clay, containing mica and ferruginous scales between the strata. Dip 1° 

south. One mile and a half below are seen similar deposits, but with no fossils, and 

containing numerous gray calcareous concretions, with veins of brown crystalline 

calcite. Two miles beyond this, on the Mexican side, is a bluff a-quarter of a mile 

long and 75 feet high, of interlarninated gray sands and chocolate clays, with sulphur 

and gypsum in places, and occasional ferruginous spots. Hard gray clay-ironstones 

with leaf impressions are also found. The sand beds are from 1 to 5 feet thick, and 

the clay is in thin laminae. Dip undulating from 1 to 5° southeast. The mica and 

black specks in the sand, the laminse of chocolate clay, the presence of sulphur and 

gypsum crystals, all show a strong resemblance to the Tertiary of east Texas. From 

here to Hardin Ferry, and thence to the mouth of Cavezeras River, are seen similar 

strata, frequently causing rapids where they cross the Rio Grande. In one place the 

indurated bluffs encroach on the river until it narrows down to 30 yards. Here the 

waters have cut a deep channel and rush through at a great velocity. Frequently 

interbedded glassy ferruginous layers, 1 or 2 inches thick, are found in the sandstone. 

Three miles below "the Hardin" is a bluff 60 feet high composed of friable sandstones, the harder and softer layers blending into each other and occasionally showing ferruginous patches. Dip 1° south. For 19 miles below this«point we pass over 

identically similar strata, frequently containing calcareous concretions 1 to 3 inches 

in diameter. These contain seams of crystalline calcite and are of a gray color, 

weathering brown or red in concentric layers.

Similar strata are seen from here to the San Tomas coal mines. These are situated on the Texas side of the river and at the mouth of San Tomas Creek, about 25 

miles by river above Laredo.

For 3 miles below this are seen indurated greenish clays with leaf impressions, 

broken stems, and specks of lignite. Occasionally seams of chocolate clay and calcareous nodules are found. As usual, the bluffs are capped with pebbles or sand, and 

dip 2° southeast. Fifteen miles above Laredo is a bluff reaching a maximum height 

of 40 feet and about 1 mile long. It is composed of interbedded coarse sand, with 

calcareous nodules, and sandy clay with gypsum and sulphur. The sand grains are 

red, yellow, white, and gray, and the whole bluff has a greenish appearance, spotted 

in places by ferruginous matter. Many similar outcrops are seen for 7 miles below, 

and as the dip is often horizontal, or nearly so, the exposures show simply different 

parts of the same bed. Eight miles above Laredo is a bluff about 80 feet high and 

half a mile long, composed of semi-indurated buff sands, with an undulating dip. 

Similar exposures are seen down the river to Laredo, and in fact that town is built 

partly on the same beds, which are here succeeded by those of the next division of 

the Eocene.

This section appears to be quite different from that observed a few 

miles inland from the river. The very sharply defined Carrizo sandstone 

appears to be absent, at least its presence was not noted.

RECONNAISSANCE BETWEEN EAGLE PASS AND CARRIZO SPRINGS AND SOUTHWEST OF CARRIZO SPRINGS.

The change from the Upper Cretaceous clays to what is probably 

the basal Eocene has already been described on page 30.

About 15 miles from Carrizo Springs the sandstone is rather fine 

grained, of a brown ocher color, and the grains are distinctly crystalline.
VAOGHAN.] EOCENE FORMATIONS. 47

Fourteen miles from Carrizo the surface of the ground is formed 

of deep red sands derived from the disintegration of a hard sandstone. 

At this locality a very few poorly preserved oysters were found firmly 

embedded in the sandstone, ^o specimens good enough for specific 

determination were obtained.

From here to Carrizo Springs deep, red sands extend the whole distance; the deepest sands are about 8 miles west of the town. There 

are occasionally more argillaceous beds. The rock whence the sands 

are derived is, before disintegration, a soft whitish or yellowish sandstone with occasional harder ledges. These are Owen's "Carrizo sands." 

They are the northward continuation of the sand seam around Chupadero ranch, and are the source when'ce the water of the artesian wells 

of the Carrizo Springs vicinity is obtained.

KfiCONNAISSANCK KKOM CARRIZO SLD HINGS TO SAN LORENZO CHEEK.

From Carrizo Springs to the Richardson ranch, 6 miles east of south

of the town, the deep sands are continuous. About opposite the house

on the ranch the soil becomes firmer, apparently containing clay

t enough to make it compact. The tank in Ainsworth's pasture, on

the southwest side of the Richardson ranch, has been excavated in

clays. Gravel occurs on the summit.of the hill near the tank. From

j this ranch to San Lorenzo Creek clays and compact sandstone are found

\ along the draws, and gravel cappings usually occur on the hills.

( NUECJES KI.VEK SUCTION.

. On the east side of the river, above the coal shaft and just below the 

Pulliam ranch, at the northern line of Zavalla County, there is exposed a soft, friable'sandstone, bkiish when fresh, oxidizing yellow, 

very often possessing a shaly appearance and containing black specks. 

This sandstone resembles very closely the basal Eocene along the Frio 

River. A half mile below the Pulliam ranch it passes below the coal 

seam and possesses a thickness of some 40 feet.

Section through coal seam.

Ft. In. 

5. Silt and gravel, fluvial................................................. 35 0

4. Laminated, brownish, shaly sandstone; contains many carbonaceous specks

and a few fossil leaves................................................ 2 3

3. Laminated, blue carbonaceous clay................;....... i ............ 5 0

2. Laminated black clay:................................................. 1 6

1. Coal, bony at top...................................................... 2 4

Total .............................................................. 45 9

Eocene exposure...................................................... 10 9

Professor Knowlton remarks that the leaves from No. 4 are probably Eocene. 0
48 - RIO GRANDE COAL FIELDS OF TEXAS. [BULL. 164.

Section down high point west side of Nueces River, just below coal shaft.

Feet.

6. Soft, yellow, friable sandstone; not much soil, vegetation mostly guajillo, 

very little grass........................................................ 20

5. Soft sandstone, oxidizing yellow, in ledges, but has a strong tendency to form 

irregular flags ......................................................... 6

4. Soft white sands, not consolidated, stratification irregular .................. 4

3. Soft laminated sand, containing some clay, about. ^........................ 20

2. Ledge of moderately hard yellow sandstone ............................... 1£

1. Shaly sandstone to water's edge in river................................... 8£

Total...............................................................'. 60

No. 1 of this section is probably No. 4 of the preceding section.

Section down bluff above the Habey ranch, west side of Nueces River.

Feet.

2. Coarse-grained, red, ferruginous sands; vegetation Opuntia rafinesquei, 0. leplocaulis, guajillo, black chaparral, Leucophyllum, Lippia, Yucca (large 

species), etc........................................................... 30

1. Soft, coarse-grained, grayish sandstone, oxidizing to deeper colors, in places 

showing seams of bluish clay........................................... 20

Total................................................................ 50

Section of bluff below the Habey ranch, west side of Nueces River.

Feet.

5. Soft yellow sandstone ledges with argillaceous partings, about............. 15

4. Soft yellowish sandstone, fine-grained, laminated, and argillaceous, with \

layers of coarse-grained sandstone at the top............................ 10 /

3. Clay, dark colored at the base............................................ 6 (

2. Coarse-grained, laminated, grayish or yellowish sandstone (top of preceding \

section) .............................................................. 20

1. The same as No. 2 of the preceding section............................... 20

Both 1 and 2 contain occasional streaks of carbonaceous clay.

Section of north end of bluff, east side of Nueces River, just above the McDaniel ranch.

Feet. 

Yellowish shales (contains several coal seams) ................................ 40

Laminated soft yellow sandstone.............................................. 10

Grayish clay shales.......................................................... 10

Total................................................................. 60

Section of south end of foregoing bluff.

Feet.

3. Coarse-grained gray sandstone, in ledges, in places very ferruginous, and in ' 

other places containing sandy concretions ..................... .......... 40

2. Laminated clays and sands, with purple or chocolate-colored streaks, caused 

, by the presence of carbonaceous matter ................................... 20

1. Coarse sandstone to water's edge........................................... 10

Total................................................................. 70

Below No. 1 are at least 75 feet of laminated sands and clays with streaks of 

purple and chocolate.
VAUGHAI-.] EOCENE FOEMATIONS. 49

Section through coal seam.

Ft. in.

12. Flaggy clay and sandstone .......................................x 25 or 30 0

11. Chocolate clays.................................................. 6 0

10. Coal............................................................ Ior2 0

9. Chocolate clays.................................................. 3 0

8. Coal............................................................ 2 0

7. Chocolate clays.................................................. 6 or 7 0

6. Coarse sand ..................................................... 1 0

5. Chocolate clay and sand.......................................... 3 0

4. Coal, weathered specimens firm but apparently not very pure; contains considerable sulphur....................................... 8

3. Bone ............................................,.^............ 3

2. Chocolate clays ................................................. 6 0

1. Clays........................................................... 20 0

Total(about).................................................. 80 0

Section of north end of bluff just below the McDaniel ranch, west side of Nueces River

Feet 

3. Gravel....................................................................60

2. Thinly laminated sandy clays and argillaceous sands, and a layer of ironstone; 

otherwise the beds are whitish........................................... 10

1. Soft whitish sands, some clay.............................................. 10

Total ..............................;.................................:. 80

, ' Section of lower (southern) end of foregoing bluff. 

( ' Feet. 

\ 3. Gravel capping.

/ 2. Soft sands and clays, usually laminated, bluish white in color, with some- 

_/ . times a chocolate tinge............................................... 30

1. Hard brownish-yellow or grayish sandstone............................. 7 or 8

Total.............................................................'.. 38

The estimated total thickness exposed in the above-described sections

is between 370 and 400 feet, giving a dip of about 100 feet to the mile

to the southeast. Supposing this dip to be continuous to the southern

boundary of the quadrangle, there would be a thickness of about 700

' feet of Eocene sands and clays within the Uvalde quadrangle along the

) Nueces River.

There are very few exposures along the Nueces River from the 

southern margin of the Uvalde quadrangle, about 1 mile south of the 

"Old 7 D" (Bucklew ranch), to the crossing of the Carrizo SpringsBatesville road over the river. The road is for almost the whole distance on the wide silt flat adjoining the river.

At the $ ranch the western bluff and bed of the river are formed of 

greenish clays, with occasional carbonaceous seams. These clays make 

an extremely sticky mud, as the writer learned from the sad experience 

of having the camp wagon bog in it.

v Five miles above S 7 ranch and about 7 miles above the crossing of 

the Carrizo Springs-Batesville road over the river, in a washout leading 

Bull. 164 4
50 RIO GRANDE COAL FIELDS OF TEXAS. [BULL. 164.

down to the river, is an exposure of yellow gypseous clays about 

20 feet in thickness. Two or 3 feet below the top of this exposure 

are nodules which upon chemical examination were .found to contain 

small quantities of lime phosphate.

RECONNAISSANCE -FROM -UVALDE -TO - CARRIZO SPRINGS, -AND FROM CARRIZO SPRINGS TO 

. ............. - - . SANTO -TOMAS. .-..-.

Twelve and..three-fourths .miles .south. of .Uvalde, on the road to 

Batesville,-crystalline' sands,, which: in all of their characters resemble 

the Carrizo-sandstone;'are-exposed. Sands of this type mixed with 

gravel were" seen about 7£ miles south of Uvalde," but no exposures of 

the sands themselves were observed. Around Loma Vista there are 

exposures of red, angular or crystalline sands. One and a half miles 

east of north" of Lonia'Vista","in the" sandstone hills around Pond's 

house, some .poorly preserved Eocene fossils were found firmly embedded in the sandstone. One species is Cornulina armig&ra (Conrad). 

This-species occurs above the Midway an,-and from it and the facies of 

some of the other fossils it would seem that the horizon of Loma Vista 

is.Claibornian, the "Lower Claiborne" of Harris.

With the above exception, from Batesville to Loma Vista and from 

the later place to the crossing over the Nueces River on the way to 

Carrizo Springs, few or no undoubted exposures below the surficial 

gravel or creek and river terraces were seen.

At the crossing over the Nue.ces River there is an exposure, 25 or 30 

feet in thickness, of laminated sands and clays, with a seam of poor 

lignite. Limonitic concretions are abundant.

; At Carrizo Springs there, are numerous flowing artesian wells, but no 

very accurate records of the borings were obtainable. The wells vary 

in depth-from 60 to 330 feet. (PI. IV, B.)

Mr. J. W. Campbell, of Carrizo Springs, furnished the following 

notes on .a well that he had bored 3 miles north of the town.

- - ' Section of well 3 miles north 'of Carrizo Springs.

Feet.

Sandstone ^ ... v ^ .................................................... 30 or 40

Hardpan and clay (about) ......__._.............._ __...___.._ ........ 260

Very coarse white sand rock to bottom of the well.:................... 6 or 16

.The well was-not. quite completed when the writer was at Carrizo 

Springs in 1898. It had been bored to a depth of 306 feet, and an 

abundant and. excellent flow of water,had been obtained in the coarse 

white sandstone at the bottom of the bore. Judge George C. Herman, 

of Batesville, subsequently stated that the boring extended to 380 feet. 

Mr. G: G. Cavender furnishes the following, record of a'well-bored 

on the S. Gpbbett.survey,: eastern bank of the Nueces River, 15 miles 

from-Carrizo Springs: ..... . . .
U. 6. GEOLOGICAL SURVEY BULLETIN NO. 164 PL. Ill

A CRETACEOUS-EOCENE CONTACT ON THE FRIO RIVER, 2 MILES BELOW 

ENGELMANN'S RANCH SOUTHERN UVALDE COUNTY.

The sandstone floor at the base of the bluff is Cretaceous; the middle and upper portions of the bluff are

Eocene,

B. BASAL EOCENE; PORTION OF SAME BLUFF, BUT FARTHER DOWNSTREAM.
VAOGHAN.] EOCENE FOKMATIONS. 51

Section of well on S. Gobbett survey.

Feet.

Soil........ ......-.... ...-- .- 1

Yellow and red clay.................................................. 5

Ked sandstone, with occasional layers of hard rock..................... 39

Clay (the local "soapstone")......................................... 20

Hard rock........................................................... 28

Soft clay and thin layers of sandstone................................. 16

Sandstone.............................-...-...------.....--.---....- 20

Clay and sand mixed................................................. 20

Water-bearing sand.................................................. 10 or 11

Total.......................................................... 147 or 148

The water rises to within 17 feet of the surface of the ground.

The sandstone around Carrizo Springs is reddish in color, rather 

coarse-grained, crystalline, and slightly micaceous.

Alternations of sandstone and clay outcrop along the road from Carrizo Springs to Encinal for about 11£ miles from the former village. 

Here they pass below clays containing calcareous and hematitic concretions. From this locality to Santo Tornas the exposures consist of 

alternations of sandstones and clays, which often contain calcareous 

concretions. The sandstones are usually soft and micaceous.

FRIO RIVER SECTION. 

t (PI. Ill, A and B; PI. IV, A.)

Section across Eocene-Cretaceous contact, % miles below the Engelmann ranch and about

5 miles due north of the southern boundary of Uvalde County.

Ft. in.

7. Eather soft yellow sandstone ........................................... 22 6

An interesting lithologic feature of this sandstone is the occurrence in 

it of large, oval, sandy nodules, which stand with their -long axes vertical. They are from 1 foot to 1 foot 6 inches in length, and vary in diameter from 3 to 7 inches. Sometimes these nodules, when broken across, 

form sandstone disks. Some of them are more nearlyo globular.

6. Soft, yellow, sandy clay, with bluish streaks; some small pebbles in the

lower part........................................................... 2 6

5. Nodules of glauconitic sandstone, usually 6inches thick; contain a considerable number of small pebbles. In the lower few inches of this layer considerable numbers of Ostrea cortex are found. It is in this layer thatZVaittilus n. sp. is found in so great abundance.............................. 6

4. Soft, yellow, very argillaceous sands, quite glauconitic. There is a ledge of 

Ostrea cortex just about the top of this 1 ayer. ATurritella, probably T. trilira 

Conrad, was also found in it. This bed is the uppermost Cretaceous.

3. Harder, sandy claystone, whitish blue and yellow in color -. .............. 1 4

2. Soft, yellow, sandy clay................................................ 8 8

1. Sandstone, originally bluish, oxidizes brown and contains fucoidal impressions. In its upper'part this stratum becomes softer and more yellowish 

and is in rather thin ledges........................................... 11 9

There are about 25 feet of Eocene strata exposed in the bluff.

Above the oyster (Ostrea cortex) ledge are 25 feet of soft sandstone 

ledges. Farther along downstream, at a still higher horizon, are 30 

feet of rather soft sandstone, very massive, and somewhat though not
52 RIO GRANDE COAL FIELDS OF TEXAS. [BULL. 164.

greatly consolidated. Above this sandstone are 6 to 8 feet of soft 

sandstone ledges. The top is some 40 to 50 feet below the bottom of 

the section opposite Myrick's lower apiary.

Section of bluff at the Myrick apiary.

Ft. in.

13. Cross-bedded and irregularly stratified sandstone or soft unconsolidated

sands, white in color but containing streaks of both yellow and red ocher. 20 0

12. Sandstone.-......................................-.....-....'.-....... 1 0

11. Blue sandy clay ...................................................... 9 0

10. Thinly laminated sandy shale ......................................... 1 0

9. Hard, fine-grained, gray sand ledge.................................... 1 0

8. Fine soft bluish sands. ..........^..................................... 4% 0

7. Sandy seam ................... -....................................... 04

6. Soft sandy shale, originally blue, weathers yellow....................... 5 0

5. Fine-grained, hard blue sandstone, fossiliferous......................... 0 6

4. Blue sandy shale ..................................................... 1 0

3. Fine-grained bluish sandstone ......................................... 1 0

2. Sandy shale layer..................................................... 2 0

1. Soft, whitish or greenish, rather fine-grained sandstone (about) .......... 2 0

Total(about) .................................... 1................. 48 0

A considerable collection of fossils was made from beds Nos. 4 and 5. 

The species are characteristic of the Midwayan Eocene.

About a half mile farther downstream an abundant and rich Midwayan Eocene fauna was found. The matrix was a yellow, somewhat 

argillaceous, and slightly glauconitic sandstone. The commonest species 

of fossils are:

Venericardia 'alticostata Conrad. 

. Cuculleea saffordi'Gabb. 

Turritella mortohi Conrad. 

Turritella humerosa Conrad.

The dip of the rocks is steadily downstream 2° or 3°.

Section of bluff on the Frio River, about 1 mile below the Lewis ranch.

Feet. 

3. Fluvial silt of variable thickness, depending upon the amount of erosion of

the rock floor. 

2. Soft white or grayish sandstone, oxidizing brown or yellow, in ledges or

laminated; some of it is ripple-marked. 

1. Blue-black clay at base. ................................................... 60

Section of hill below Mexican ranch, on the Frio River below the Lewis ranch.

Feet. 

Capping of flint gravel.

Coarse-grained gray sandstone, exposed beneath the flint gravel \ c 

Flaggy sandstone ........ '. .... 1............................../""""""""

Soft shaly sandstone, about. ................................................... 10

Flaggy brown sandstone..................................................... 5

Soft sandy shales......."..................'.................. ^..........:.... 20

Total................................................................ 40
U. S. GEOLOGICAL SURVE 1UL.LETIN NO. 164 PL. IV

A. LOWER EOCENE SANDSTONE, MYRICK S APIARY, FRIO RIVER, SOUTHERN UVALDE

COUNTY.

]i. ARTESIAN WELL, DINMAN'S, NEAR CARRIZO SPRINGS.
VAXJGHAN.] . EOCENE FOEMATIONS. 53

Section of bluff next lower down on the west side of the Frio River.

Feet. 

6. Coarse-grained brown ferruginous sandstone............................. 20

5. Soft white or yellowish sand.............................................. 8

4. Clay searn, with thin streak of lignite..................................... 7

3. Soft white sands, sandy clay at base................ ....>................... 20

2. Sandy shale............................................................. 2

1. White sandy clay........................................................ 3

Total 60

The total thickness of the Eocene in the Uvalde quadrangle is probably about 850 feet.

CONCLUSIONS REGARDING THE EOCENE.

From the foregoing discussion of the Eocene-Cretaceous contact, 

and from the sections of the Eocene, it has already been made evident

FIG. 5. Weathering of the Carrizo sandstone at Chupaclero ranch.

that there is not yet sufficient data to trace accurately the boundary 

between the Cretaceous and the Eocene. This boundary crosses the 

Rio Grande some miles, at least 4 or 5, above the north line of Webb 

Count}^; it runs northeastward 1 or 2 miles northwest of India ranch, 

and passes some 16 miles west of Carrizo Springs. From here the 

boundary continues northeastward, and crosses the Nueces River about 

the north line of Zavalla County. It continues north of east to the 

Frio River, crossing that stream 2 miles below the Engelmann ranch, 

and 5 miles, in a straight line, north of the south line of Uvalde County. 

The last-mentioned point is the only absolutely determined contact. 

The others are supposed or inferred from the data at hand.

The whole Eocene strata are sandstones, varying in hardness, coarseness of grain, and amount of contained argillaceous material, and clays, 

varying in the amount of contained arenaceous material and often con-
EIO GRANDE COAL FIELDS OF TEXAS. [BULL. 164.

taining lignite beds. The actual base of the series in the positively 

.known and inferred localities is sandstone. The immediately succeeding beds may be mostly sandstones, as along the Frio, or there may 

be much -clay; as along the Rio Grande. The variations of the sections 

can be discovered "only by very detailed mapping.

The coarse-grained Carrizo sandstone seems a fairly persistent member. It outcrops around the Chupadero ranch, between India ranch 

and San Lorenzo Creek, and extends northward on the west side of 

Carrizo ' Springs. A very similar sandstone outcrops in the hills 

around the Turk ranch, in the northwestern corner of Zavalla County,

FIG. 6. Sandstone and clays above coal horizon (Santo Tomas seam) at Santo Tomas.

and near the Habey ranch on 'the Nueces. It is seen 12i miles south 

of Uvalde, between the Lepna and Nueces rivers, along the road to 

Batesville, and apparently extends southward to Loma Vista. It also 

occurs on,the divide in southern Uvalde County, between the Leona 

and Frio. rivers. ' .

Above this sandstone are alternations of finer-grained sandstones 

and clays, and it is in these sandstones and clays that most of the lignite beds occur.

NEOCENE AND PLEISTOCENE.

The formations of these ages have received so much attention in the 

paper entitled Geology of the Edwards Plateau and Rio Grande Plain, 

etc., 1 that it does not appear necessary to say a great deal here.

i Eighteenth Ann. Kept. U. S. Geol. Survey, Pt. II.
BULLETIN NO. 164 PL. V

SHOWING THE UPPER PLAIN (UVALDE FORMATION LEVEL) AND THE WiDE SILT

ERRACE (COLUMBIA FORMATION LEVELi
VAUGHAN.] NEOCENE AND PLEISTOCENE DEPOSITS. 55

NEOCENE.

In the area that is the subject of this paper the summits and high 

divides are the remnants of a plain the general features of which have 

been previously described. This plain was once entirely covered with 

a surface coating of gravel to which Hill has given the name.".Uvalde 

formation." These deposits form the top of the bluff along the Rio 

Grande from Del Rio to beyond Santo Tomas, occupying a position 150 

to 200 feet above the river and extending eastward far beyond the 

limits of the area discussed.

PLEISTOCENE.

Below the level of the Uvalde formation several terraces have been 

developed along the principal stream. The uppermost of this series 

of terraces usually occurs about 120 feet below the Uvalde formation,

..MILE.

FIG. 7. Section of bluffs and terraces at Palafox.

at the foot of the bluff forming the walls of the Rio Grande Valley. 

This terrace is generally several miles wide, and is composed of 

fine gray calcareous silt. Beneath it are several narrower silt terraces. Terraces occur on all of the other streams, but they will not 

be described here.

FIG. 8. Generalized diagram of Rio Grande terraces.

ECONOMIC GEOLOGY.

EAGLE PASS COAL FIELD.

EXTENT.

As stated in the introduction, this coal field lies partly in Texas and 

partly in Mexico. It extends from Sabinas, Mexico, northeastward to 

Eagle Pass, crossing the.Rio Grande some 5 or 6 miles above the latter 

town.- It continues for more than 85 miles tS the north of this town. 

In the vicinity of Eagle Pass the coal horizon dips at a rather steep
56 EIO GRANDE COAL FIELDS OF TEXAS. [BULL. 164.

angle, and soon plunges beneath the overlying sandstones and clays to a 

depth too great for profitable working. Concerning the extent of this 

field in the Santa Rosa district of Mexico, Hill says: 1

This coal field (the Santa Rosa) is the foundation of the whole valley or plain, and, 

except where covered by remnants of the later volcanic and conglomerate terrace, 

it is everywhere exposed. Next to the Sierra Chiquita, or Hog Backs, the coal is

DOLCH, DIBRELL AND MOSHEIM {

IAVERICK COUNTY 

COAL CD'S MINE

2IOFEETTOCOAI,

FIG. 9. Sketch map showing coal mines and prospects near Eagle Pass; furnished by Louis Dolch.

turned up in vertical stratification and is worked within a quarter of a mile of the 

entries of several mines. The coal beds extend from the foot of the Santa Rosas northward over the entire valley of the Sabinas, and at San Felipe, some 28 miles northeast 

of the concession, the coals are extensively mined and the product shipped to Texas, 

New Mexico, and Mexico in enormous quantities. These coals are not to be compared 

with the imperfect fibrous lignites of eastern Texas or the impure Carboniferous coals 

of that State, but they are the true Rocky Mountain Cretaceous coals, of anthracite 

luster, and by far the best fuel in America except the true anthracites of Pennsylvania, ranking higher than tiie bituminous of the Appalachian region.

1 Keport to the Ministro de Fomento upon the geology of the Santa Rosa mining district.
VATJGHAN.] EAGLE PASS COAL FIELD. 57

Owen measured sections of the coal bed at three places in the Hartz 

coal mine, 5 miles northwest of Eagle Pass. At one place there were 

4 feet and 6 inches of good coal, without any division of slate; at 

another place there were 5 feet and 4 inches of coal, with three divisions of slate aggregating 14 inches, leaving 4 feet and 11 inches of 

coal; at a third place the stratum was 7 feet and 3 inches thick, with 

five divisions of slate aggregating 14 inches. This gives a coal stratum 

with an average thickness of over 5 feet. 1

The seam mined in the shaft of the Maverick County Coal Company is, according to Mr. George Bregg, the manager, 6 feet thick. 

He did not state whether there are any divisions of slate or bone. The 

coal is overlain by clay and underlain by sandstone. The seam in the 

Fuente mines (Mexico), opposite Eagle Pass, is 4 to 5 feet thick, and 

is both overlain and underlain by clay. Six feet of coal were passed 

through in boring the artesian well near Eagle Pass.

Mr. Louis Dolch, of Eagle Pass, furnished the accompanying sketch 

map (p. 56) showing the location of the prospect shafts sunk for coal.

The following are the detailed sections through the coal seams, 

given by Mr. Dolch:

Prospect shaft No. 1.

Ft. in.

Depth to coal......................;..................................1. 90 0

Coal..........................................................'.......... 0 29

Slate................................................................... 0 6

Coal...........................................................;........ 0 16

Slate ................................................................... 0 4

Coal.................................................................... 0 34

Slate ................................................................... 0 4

Coal...................................'................................. 0 4

Total coal and slate................................................ 0 97

There are 83 inches of coal, with three divisions of slate.

Prospect shaft No. 8

Ft. in.

Depth to coal.......................................................... 134 0

Coal................................................................... 0 32

Bone.................................................................. 0 13

Coal................................................................... 0 8

Bone.......................................-....'...-.................. 0 -2

Coal................................................................... 0 24

Total coal and bone........................... r .................. 0 79

A total of 64 inches of coal, with two divisions of bone.

1 First Kept, of Progress of Texas Qeol. Survey, 1889, p. 70.
.. .,.. . , . ,

I

'58 EIO GKANDE COAL FIELDS OF TEXAS. " [uuLi..464.

Prospect shaft JVb." 3 (worked seam).

Inches. 

Coal.........................!...............................-....... ..... 28

Bone ..............^....................................................... 6 '

Coal....................................................................... 16

Reddish clay............................................................... 3

Coal............................'............................................ 10 v

White clay.......'.......................................................... 2

Coal....................................................................... 18

i __

Total................................................................ 83

This gives a total thickness of 72 inches of coal, with three divisions V

of slate. Whether all of this coal is marketable is not known.

* 

Mr. Peter W. Thomson furnishes the following information:.

Prospect shaft sunk 6 1-2 miles north of Eagle Pass. "

	Ft. in. 

Gravel, sandstone, etc ................................................... 45 0

Coal......................:.............................................. 0 7

Slate ......................................'-........................^.... 0 2

Coal.................................................................... 0 32

Slate ................................................................... 0 2 ;

Coal.................................................................... 0 7 V

Slate .....-.- -.!...-..--......-...----..-.-..-------.-----------..---.-- 0 2

Coal...^............................................................... 0 7

Slate ................................................................... 0 3\

Coal........_.....................:...........................'.......... 0 4 \

Fireclay ............................................................... 0 10 )

Coal...-...-..........!.............-.....-...........----.--..-..----.- 0 17

Slate .................................................................... 0 4

Coal.................................................................... 0 7

Total coal, slate, and clay .-.................:...................... 0 104

There are 81 inches of coal, with six divisions of slate or clay.

Prospect shaft sunk in Olmos Creek bottom, 7 miles north of Eagle Pass. 

Ft. in.

Gravel, sandstone, etc ..-................................................. 39 0

Coal.......................!............................................ 0 26

Slate................................................................... 0 6

Coal....................-..........--.-............-..............:...... 0 11

Fireclay...-........--............-.--..........?...........-.-......... 0 6 

Coal.................................................................... Q 6

Fireclay................................................................ 0 16

Coal.................................................................... 0 20

Total coal, slate, and clay ........................................... 0 91

Giving a total of 63 inches of coal, with three divisions of slate and 

clay.
VAUGHAN.] EAGLE PASS COAL FIELD. ' 59

Prospect shaft 8 miles north of Eagle Pass, on the Southern Pacific Railroad.

' Ft. in.

Soil, gravel, sandstone, etc............................................... 45 0

Coal.................................................................... 0 39

Slate .................................................................... 0 9

Coal.................................................................... 0 15

Slate ...........-....................-..............:................... 0 2

Coal.................................................:.................. 0 2

Slate ................................................................... 0 7

Coal.................................................................... 0 13

Slate ................................................................... 0 1

Coal..................................................................... 0 10

Total coal and slate.............................,................... 0 98

Here there are 79 inches of coal, with four divisions of slate. The 

aggregate thickness of the slate, including the valueless 2 inches of 

coal, is 21 inches..

The writer possesses no data on the chemical properties of the coal 

obtained in these prospects, and can give no information regarding 

its quality. It is very evident that the Eagle Pass coal extends farther 

to the north than any exploitations yet made. "At Thompson's ranch 

(Olnios siding) the same bed was struck at 150 feet, the level at the 

surface being a little lower at Breckenridge shaft upon the same property, and the dip balancing the gain. At McKenzie's, farther east, at a 

lower level topographically, the combined effect of dip and erosion has 

brought the surface within 20 feet of the coal." 1

Besides making such observations as were possible, inquiries were 

made of ranchmen, county surveyors, and- other persons who would 

likely know of the existence of coal beds. Mr. O. P. Hector, county 

surveyor of Maverick County, states that in a well on his place, 2£ 

miles below Eagle Pass, coal was struck at a depth of 65 feet, and that 

the seam is 6 or 7 feet thick.

Mr. Hector was asked whether he knew of any outcrops of coal 

along Salado, Chacon, Palo Blanco, or Mula creeks. He replied: 

"No outcroppings of coal along any of the above streams." The 

Eagle Pass coal extends some distance north of Eagle Pass, at least 

beyond the Thomson ranch, but because of dearth of exposures and a 

lack of any records, the actual distance could not be determined. It 

would seem worth while to prospect farther north. Mr. S. D. Frazier, 

of Carrizo Springs, in boring a well on the ranch of Simpson and 

Mangum, in Zavalla County, on Mula Creek 2 or 3 miles above where 

it empties into Palo Blanco Creek, struck coal at a depth of 120 feet; 

but the coal is worthless. This coal is probably in the Cretaceous area.

It is certain, however, that the Eagle Pass coal field does not extend 

to the Nueces River. All of the coal around Eagle Pass occurs below 

the Ostrea cortex horizons, while along the Nueces there is no coal

1 T. B. Comstock: Second Kept, of Progress of Texas Geol. Survey, Austin, Tex., 1892, p. 53.
60 RIO GRANDE COAL FIELDS OF TEXAS. [BULL. 164.

below the dstrea cortex ledge. All of the coal (or lignite) along this 

stream occurs above the oyster ledge and in all probability is Eocene. 

This coal is discussed under the Eocene coals or lignites (pp. 61 and 62). 

One other occurrence of coal is reported in the Eagle Pass formation. Mr. Robert Thomson states that a 4-foot seam of coal was 

penetrated in a well bored by him on the line between Maverick and 

Zavalla counties, about 4 miles north of the northern line of Dimmit 

County. The writer has no further information in regard to this 

occurrence.

' MINES.,,

Two mines are at present being worked in the Eagle Pass coal bed, 

in the vicinity of Eagle Pass. One is that of the Maverick County 

Coal Company, situated on the east side of Elm Creek, 4 miles north 

of Eagle Pass. A section .of this mine is given on page 25. It was 

opened in 1895. The other mine was opened by L. F. Dolch & Co. in 

1898, and is about a mile south of the mine of the Maverick County Coal 

Company. The shipping of coal from the Dolch mine was begun in 

January, 1899. It is now owned by the Rio Bravo Coal Company. 

A section in this mine is given on page 24. The old Hartz mine, 

about 5 miles above Eagle Pass, on the Rio Grande, was worked on 

a slope, and is now abandoned.

CHARACTER OF COAL.

Specimens of the Eagle Pass coal were collected, and on them the 

following notes are based:

The coal is dark, does not air slack, is lustrous or brownish black 

in color, has a brown streak and subcubical'cleavage. Usually no 

woody structure is apparent.

Two analyses, made by Dr. Peter Fireman, of Columbian University, 

showed a rather low percentage of water, a ratio of fixed carbon to 

volatile hydrocarbon of 1.11 and 1.05. The percentage of ash was high.

The following is one of the analyses:

Analysis of Eagle Pass coal.

Moisture .............................................

Volatile hydrocarbon. . ................................

T, .- F- 0. 1 Ratio VHC |..-. ........ ...... ..................... 

Ash..................................................

Color of ash. ..........................................

Coke............................ ....................

2.50

40.60

42.72

1.05

14.18

O
VAUGHAN.] EAGLE PASS COAL FIELD. 61

Penrose gives the following analysis of the Eagle Pass coal: l

Analysis of Eagle Pass coal.

Water ..................................................

T7i vpH pa vhAn

Ash....................................................

Per cent.

3.675

39.42

41.7

15. 205

0.81

The following data concerning some of the coal of the Santa Rosa 

region are extracted from a paper by Hill, 2 in which he states that, 

according to Professor Rock, the following is an analysis of that coal:

, Analysis of coal from Santa Rosa region.

Coke........:..........................................

Ash....................................................

By computation this coal should have 

Volatile hydrocarbon (approximately) ................

Ratio F^-}.. ................................

V. xl. U.J

5.75 

77. 147

3.53

1.41

73. 617

17. 103

4.3

In the ash, silica and iron predominate. No coal so good as the 

Mexican article has yet been discovered in Texas.

EOCENE COAL FIELDS.

EXTENT OF THE EOCENE COAL FIELDS, INCLUDING THE SANTO TOMAS

FIELD.

The most northern exposure of lignite observed in this region is that 

in the east bank of the Nueces River at the north line of Zavalla 

County,' about a half mile below the Pulliam ranch. When this locality was visited about 2 feet of coal were exposed. Owen makes the 

following note on this outcrop:

Fourteen miles southwest of Uvalde, on the line between Uvalde and Zavalla 

counties, there is an outcrop of coal in the north bank of the Nueces River. At 

this place the stratum is 4 feet 10 inches thick, with a 3-inch division of slate in 

the center. 3

1 First Ann. Kept. Geol. Survey of Texas, 1890, p. 98.

8 Report to Ministro de Fomento upon the geology of the Santa Rosa mining district.

3 First Kept, of Progress of Texas Geol. Survey, 1889, p. 69.
62 RIO GRANDE COAL FIELDS OF TEXAS. [BULL. 164.

Dumble states that "the coal has been used by blacksmiths at the 

fort [Fort Inge] and found to be of good quality." 1

Going down the Nueces, the next outcrop of coal is in the east bank 

of the river, just above the McDaniel ranch. The following is a section 

through the coal seam:

Section through coal seam above the McDaniel ranch.

Chocolate-colored clays. Feet. inches.

Coal, not clearly exposed......................................... Ior2 0

Chocolate-colored clay........................................... 3 0

Coal........................................................... 1 " 10 or 11

Chocolate-colored clay .......................................... 6 or 7 0

Coarse sand.................................................... 0 11

Chocolate-colored clay and sand................................. 3 4

Coal............-..:............-..........-................... 0 8

Bone .................................. I........................ 0 3

Chocolate-colored clays ......................................... 6 0

 .

This exposure is in a weathered bluff, the bottom being about 20 

feet above the water in the river, at the time of the inspection. As 

appliances for digging and obtaining 'good samples were not at the 

writer's disposal, no opinion regarding the value of the coal can be 

expressed.

Mr. M. C. Ott furnished Mr. Hill with the following data: " In a well 

3 miles east of the Nueces River, in TJvalde County, on the road from 

Uvalde to Carrizo Springs, coal was struck in three places; one seam, 

at a depth of 150 feet, was 5 feet thick."

The writer can not locate this well on any map, and can give no 

further information concerning the coal than to suggest that it may be 

the same seam exposed just below the Pulliam ranch.

Coal is reported from the following other localities north of Carrizo 

Springs: There is, as already noted, an outcrop at the bridge, where 

the Carrizo Springs-Batesville road crosses the Nueces. There is coal 

at the mouth of Espantosa Slough, but nothing definite is known concerning it. Mr. S. D. Frazier informs the writer that he struck a 7-foot 

seam of coal at a depth of 80 feet, in a well bored for Mr. Coleman on 

Penya Creek.

Santo Tomas coal field. Probably the foregoing outcrops of coal 

should be included in the Santo Tomas coal field, but in order to 

avoid attempts at correlations or suggestions as to equivalence in age, 

they have been discussed separately. The Santo Tomas coal series 

will, therefore, be assumed to begin 11 miles below the Guajolote 

ranch.

Eleven miles by road, southeast of the Guajolote ranch, is an outcrop of coal or lignite. The associated rocks are micaceous sandstones 

and clay shales. The record of prospect drill No. 6, bored by Mr.

1 Brown Coal and Lignite, p. 188.
VAUOHAN.] EOCENE COAL FIELDS.. 63

D. D. Davis at Pilot ranch, 25 miles west of north from Santo Tornas, 

and 3i miles from Rio Graride, is given on pages 42 to 44. There is 

another outcrop of coal 2£ miles north of Palafox.

At Santo Tomas there are two mines, that of the Rio Grande Coal 

and Irrigation Company, which is in the village, and that of the Cannel Coal Company, which is 3 miles southeast of it. The record of 

the prospect drill bored at the latter mine has been given on pages 

41 to 42. In the Cannel Coal Company's mine there are two seams, the 

upper one being called the Santo Tomas seam (Rio Grande Coal and 

Irrigation Company), and the lower one, known as the San Pedro 

seam, being worked by the Canriel Coal Company.

Section of the .Santo Tomas seam.

7. Carbonaceous shale roof, 'soft, requires considerable timbering. Ft. in.

6. Coal!................................................................ 0 14

5. Bone ........:....................................................... 0 4

4. Coal................................................................. 0 14

3. Bone ................................................................ 0 6

2. Fireclay.............................................................. 7 0

1. Sandstone.

*

Section of the San Pedro seam.

Ft. in.

8. Clay slate or sandstone................................................ 0 14

7. Carbonaceous shale................................................... 0 £

6. Coal, upper bench.................................................... 2 0

5. Bone ................................................................ 0 15

4. Clay.................................................................. 2 0

3. Lower bench:

c. Good coal................ ......................................... 0 6

b. Bone ............................................................ 0 2

ft. Good coal........................................................ 0 11

2. Carbonaceous shale.................................................... 0 3

1. Sandstone............................................................. 14 0

The following is extracted from Dumble's Brown Coal and Lignite, 

page 189.

The most northern exposure of this c6al observed in Webb County was about 25 

miles northwest of Santo Tomas, where a seam of pitch coal was found which was 

black, massive, dense, and so firm that it does not give a greasy streak with finger 

nail. No trace of wood structure, subconchoidal fracture.

About 8 miles west of Santo Tomas, at Espada Creek, we find- three seams of brown 

coal.

The upper seam is 12 inches thick, and is a massive pitch coal with conchoidal 

fracture, very similar to the body of the Santo Tomas coal. It is underlaid by 4 feet 

of shale, and this by the Santo Tomas seam of coal, which is here 34 inches thick with 

a 2-inch division of slate. This coal is underlaid by 30 feet of shale, below which is 

a third seam of brown coal, varying in color from light to dark brown, with many 

traces of woody structure, impressions of leaves, etc.
RIO GRAKDE COAL FIELDS OF TEXAS. [BULL. 164.

MINES.

There are only two mines in the Santo Tomas coal field. They have 

been mentioned already, and are the Santo Tomas (Rio Grande Coal 

and Irrigation Company) mine at Santo Tomas, and the mine of the 

Cannel Coal Company, 3 miles southeast of Santo Tomas. The 

coal in the Santo Tomas is mined on a slope (tunnel). Work was 

begun at 31 feet above the level of the Rio Grande, and has been prosecuted through 2,400 feet, to the level of the river. The dip is 2° N., 

40° E. The mine has been in operation about fourteen years (1895). 

The output is from 90 to 100 tons daily, and most of it is sold to the < 

International and Great Northern Railroad.

The Cannel Coal Company take their coal from a shaft. At the 

time of the writer's visit to the mine (1895) the shaft had been completed, entries driven, and everything was ready for actual mining to 

begin, but up to that time no coal had been shipped.

(

CHARACTER OF COAL.

The coal of the Santo Tomas field is hard, lustrous black, with a i 

brown streak and a conchoidal fracture. No woody structure was C 

apparent.

The following analyses were made for the writer by Dr. Peter , 

Fireman: v '\

Analysis of coal from mine of Rio Grande Coal and Irrigation Company.

Moisture .............

Katio * =%} .......

V. xl. \j.) '

Ash..................

Coke.................

Upper bench.

2.26

48.64

36.15

.74

12.95

Coherent, lustrous.

Lower bench.

2.63

45. 67

39.96

.87

11.74

Brown.

Coherent.
VAUGHAN.] EOCENE COAL FIELDS.

Analysis of coal from mine of Cannei Coal Company.

65

Upper bench. Upper part of 

lower bench.

Lower part of 

lower bench.

Moisture ..........

Vol. hydrocarbon . . 

Fixed carbon ......

Ratio

Ash........

Color of ash . 

Coke.......

2.70

49.99

' 37. 55

.75

9.76 

Yellowish gray.

Coherent, hard, 

partly lustrous.

2.01

48.33

33.15

.68

16.51

Light brown. 

Partly sooty.

2.33

49. 35

38.08

.77

10.24

Light brown. 

Coherent.

Dumble 1 gives the two following analyses of coals from the Santo 

Tomas coal field (specimens collected by J. Owen):

Analysis of pitch coal from outcrop 25 miles northwest of Santo Tomas, thoroughly air

dried.

Per cent.

Moisture. ..................................................... 2. 35

Volatile matter. ............................................... 42. 67

Fixed carbon .................................................. 37. 57

Ash .......................................................... 16. 55

Sulphur ...................................................... - .86

Analysis of coal from Santo Tomas coal mine.

Per cent.

Moisture. ...................................................... 2. 59

Volatile matter ................................................ 51. 05

Fixed carbon ................................................. 39. 01

Ash .......................................................... 7. 35

Total ..................................................... 100. 00

"Sulphur ...................................................... 1. 50

1 Brown Coal and Lignite, p. 190.

Bull. 164
66 BIO GKANDE COAL FIELDS OF TEXAS. [BULL. 164.

Penrose says : 1 " The San Toraas coal is so vastly superior to any of 

the east Texas lignites that it can not fairly be classed with them." 

He gives the following analyses of the east Texas lignites and of the 

Laredo and Eagle Pass coals. They are presented here for purposes

of comparison.

Analyses of Texas lignites.

Kockdale, Milam County ......

Athens, Henderson County ....

Calvert bluff, Robertson County

Leon County .................

Water.

Per cent. 

19. 925

13. 285

9.100 

16. 825

16. 475 

18. 260

14. 670

13.800

Volatile 

matter.

Per cent. 

52. 425

59. 865

42. 200 

46. 325

58. 400 

43. 510

37. 320

43. 550

Fixed 

carbon.

Per cent. 

22. 000

18. 525

7.375 

31. 475

18.675' 

29. 530

41. 070

36. 830

Ash.

Per cent. 

5. 650

'8.325

41. 325 

5.375

6.450 

o 8.700

6.690

5.320

Sulphur.

Per cent. 

1. 235

2. 360 '

0.625 

].090

1. 330 

2.460

0.250

1.350

Analyses of Laredo and Eagle Pass coals.

Eagle Pass coal ................

Water.

Per cent. 

2.5

3.675

Volatile 

matter.

Per cent. 

51. 05

o 39.42

Fixed 

carbon.

Per cent. 

39.1

41.7

Ash.

Per cent. 

7.35

15. 205

Sulphur.

Per cent. 

1.5

0.81

CONCLUSIONS REGARDING THE RIO GRANDE EOCENE COALS.

These coal (or more properly lignite) fields are simply the westward 

continuation of the great lignitiferous Eocene belt of eastern Texas and 

the Gulf States as far east as Alabama. The coal beds of the Rio 

Grande region range in position from Midwayan to Chickasawan. 

The beds on the Neuces, in northern Zavalla County, are Midwayan, 

while those around Carrizo Springs and Santo Tomas are Chickasawan.

Although the Eocene contains many lignite^ beds, most of them are 

not of economic value for various reasons. They are often thin and 

impure, and, because of a large content of moisture or because of an 

unconsolidated mechanical condition, must undergo mechanical treatment by being pressed into briquettes. These questions are discussed 

by Durable in Brown Coal and Lignite. 2

The only place where these Eocene coals are being worked is in the 

vicinhVy of Santo Tomas. The coal there is sufficiently hard to need no 

treatment. In such an investigation as this it is not possible to make

1 First Ann. Kept. Geol. Survey of Texas, 1890, p. 97,

2 Geol. Survey of Texas, 1892.
VAUGHAN.] LITEBATUBE. 67

special examination of particular localities. All that can be done is to 

indicate places and give such data as may be collected under the conditions of the work, as a guide for future detailed examinations.

LITERATURE.

The following annotated bibliography may be of assistance to those 

interested in the history of geologic investigation in this region: 

1857. SCHOTT (Arthur). Substance of the sketch of the geology of the Lower Bio 

Bravo del Norte: Reports of the Mexican Boundary Survey, Vol. J, Pt. II, pp.

28-48.

This article is a preliminary reconnaissance and contains no detailed 

stratigraphic work. Schott's observations, taken in connection with 

the determination of the fossils by Conrad, showed the existence of 

large areas of Cretaceous rocks in the region covered by his reconnaissance, i. e., from the mouth of the Pecos River to a point between 

Eagle Pass and Laredo. After personally studying the region, some 

of the beds in Schott's description will be recognized as those which 

have since been specifically named. Between the Pecos and Del Rio 

, Schott observed the" peculiar buttes formed from the .Exogyra arietina 

(Del Rio) clays. He made observations on the coal-bearing beds in the 

vicinity of Eagle Pass, and noted outcrops of coal near Palafox. 

./ 1882. ADAMS (W. H.). Coals in Mexico, Santa Kosa district: Am. Inst. Mining 

 1 Engineers, Vol. X, pp. 270-273.

The paper of Mr. Adams is one of the first and best descriptions 

of the Lower Rio Grande coal fields as a whole, although he made 

erroneous deductions concerning their exact age. From lithological 

characters he referred the Santa Rosa coal to the Trias, and for similar 

reasons he referred the Eagle Pass coal to the Permian.

1884. LOUGHRIDGE (B. H.). Report on the cotton production ot the State of Texas: 

. Tenth Census of the United States, Vol. V.

This publication contains several notes on the general geology of the 

region of the Rio Grande Plain.

1884. COPE (E. D.). A note on the geology of the vicinity of Laredo: Proc. Am. 

Philos. Soc., Vol. XXI, p. 615. 

Cope considered the lignite-bearing beds (the Santo To'mas coals) 

above Laredo as Laramie, and stated that they are immediately overlain by the Claiborne.

1885. McGEE (W J). Geological map of the United States: Fifth Ann. Rept.U. S. 

Geol. Survey.

McGee represents the northern boundary of the Eocene as reaching 

almost to the twenty-ninth parallel on the Rio Grande, and the southern 

boundary as crossing that river south of the twenty-eighth parallel and 

a little east of the ninety-ninth meridian. 0

1886. HiTcncocK (C. H.). Geological map of the United States: Trans. Am. Inst. 

Mining Engineers, Vol. XV.
68 KIO GKAKDE COAL FIELDS OF TEXAS. [BULL. 164.

Hitchcock's map is based on McGee's.

1887.. WHITE (C. A.). On the age of the coal found in the region traversed by the 

Rio Grande: Am. Jour. Sci., 3d series, Vol. XXXIII, January, 1887, p. 18.

After examining the coal in the vicinities of Eagle Pass and Santo 

Tomas, and after studying collections of fossils^ White concluded that 

the coal beds were of late Cretaceous age, i. e., Laramie or Fox Hills.

1887. HILL (R. T.). Topography and geology of the cross timbers and surrounding 

regions in northern Texas: Am. Jour. Sci., Vol. XXXIII, pp. 291-303.

A preliminary map of The Salient Topographic Features of the 

State of Texas accompanies this article.

1887. HILL (R. T.). The Texas section of the American Cretaceous: Am. Jour. Sci., 

Vol. XXXIV, pp. 287-309.

On page 290 a map is given which represents, according to then 

existing knowledge, the areal distribution of the various geologic 

formations in Texas east of the one hundredth meridian. The Balcones 

fault is described, and its influence on the topography stated. On page 

294 it is stated that the Navarro beds of Texas and the Fox Hills beds 

of the Northwest meet in the Rip Grande region. On page 302 Hill 

states that he has good authority for asserting the occurrence of strata 

of the Washita division '' westward to the Rio Grande, beyond Eagle 

Pass." 

1888. WHITE (C. A.). On the relations of the Laramie group to the earlier and 

later formations: -Am. Jour. Sci., Vol. XXXV, pp. 432-438.

This article contains a brief account of a journey from Eagle Pass 

to Laredo. According to White,'the coal-bearing beds, at Eagle Pass 

represent the Fox Hills group of the western section and the Ripley 

group of the eastern section.. The beds containing the Eagle Pass coal 

pass below the beds containing the Santo Tomas coal. The latter beds 

are considered of undoubted Laramie age. This so-called Laramie is 

immediately overlain, in the vicinity of Laredo, by beds containing 

Claiborrie fossils. The upper part of the Laramie is considered of 

Eocene age.

1888. HILL (R. T.). The Neozoic geology of southwestern Arkansas:. Ann. Rept. 

Geol. Survey of Arkansas, 1888.

On page 101 Hill mentions that the "Rocky Comfort" (Austin) chalk 

extends from Arkansas to Maverick County, Texas. On the same page 

it is stated that evidence is found that the Gulf and interior provinces 

of the Cretaceous unite in the region of Eagle Pass. It is also stated 

(p. 47) that the Rio Grande is an example of "-an old Quaternary 

valley, filled with sediments cut through by the more recent streams."

1889. OWEN (J.). Report in First Report of Progress of the Texas Geological Survey, pp. 69-74.

Although Owen did not apply names to the different beds which he 

examined, he has given so.clear descriptions of them that every bed 

from the Edwards limestone to the Eocene can be identified. He 

recognized the relative stratigraphic positions of the Eagle Pass and the
VAUGHAN.] LITERATURE. 69

Santo Toinas coal beds, and noted the existence of the sands (Carrizo) 

which come above the Eagle Pass beds and cany the water supplying 

the artesian wells at Carrizo Springs.

1889. HILL (R. T.). A preliminary annotated check list of the Cretaceous invertebrate fossils of Texas: Bull. No. 4, Geol. Survey of Texas, Austin, 1889, pp. 

xii-xxxi, 1-57.

Contains some notes applicable to the Rio Grande region and gives 

localities for some of the fossils.

1890. PENROSE (R. A. F.). A preliminary report on the geology of the Gulf Tertiary 

of Texas from Red River to the Rio Grande: First Ann. Rept. Geol. Survey of 

Texas, pp. 3-101.

On pages 38 to 47 a description is given of a section along the Rio 

Grande from Eagle Pass to the mouth of the river. The three points 

of special interest in this paper are:

(1) The description of the plain character of the country.

(2) The ammonites hitherto found at Eagle Pass are shown to occur 

along the river to near the Webb County line.

(3) The section (page 41) of Webb bluff 3 miles below the north line 

of Webb County. Here Eocene rnollusks were found.

On page 60, in discussing the upland gravel, Penrose states that the 

gravel along the Rio Grande is frequently cemented, by a calcareous 

matrix, into a conglomerate. The pebbles of the gravel, or conglomerate, are of "limestone, flint, quartz, chalcedony, agate, black obsidian, 

red pitchstone, jasper, and porphyry."

On page 62 is a description of the Rio Grande silt. On page 63 the 

name Reynosa limestone is proposed for a hard, white, post-Tertiary 

rock occurring in the town of Reynosa, 250 miles below Eagle Pass, 

State of Tamaulipas, Mexico, at an elevation some 50 feet above the. 

Rio Grande.

1890. HILL (R. T.). Classification and origin of the chief geographic features of the 

Texas region: Am. Geologist, Vol. V, Nos. 1 and 2.

In No. 1 there is an Approximate Map of the Topography and Geology of the Texas Region.

1891. HILL (R. T.). The Comanche series of the Texas-Arkansas region: Bull. Geol. 

Soc. America, Vol. II, May, 1891, pp. 503-528.

In this paper several allusions are made to the geology of the vicinity of Del Rio. On page 517 the presence of the Fort Worth limestone and the Exogyra arieti/iia clays is announced, and on page 519 the 

occurrence there of an Equisetum and a Nodosaria is made known.

1891. HILL (R. T.). Notes to the geology-of the Southwest: Am. Geologist, Vol. 

VII, pp. 366-370.

On page 366 Hill states that Nodosaria texana Conrad, a fossil'of the 

Denison' beds, and their southern continuation, the Exogyra arietina 

clays, forms great masses of limestone at Del Rio. On pages 367 and 

368 the Tertiary basin of the Lower Rio Grande is described, and the
70 BIO GRANDE COAL FIELDS OF TEXAS. [BULL. 164.

name Uvalde formation is proposed for the extensive upland gravel 

sheet blanketing that region.

1891. HILL (R. T.). Preliminary notes on the topography and geology of northern 

Mexico and southwest Texas and New .Mexico: Am. Geologist, Vol. VIII.

On page 135 " the westward embayment of the Rio Grande from the 

coast" is described.

1891. WHITE (C. A.). Correlation papers Cretaceous: Bull. U. S. Geol. Survey 

No. 82.

On pages 116 and 117 reference is made to the region between Eagle 

Pass and Laredo. The same opinion that was expressed in the American 

Journal of Science, Vol. XXV, concerning the presence of Laramie 

along the Rio Grande below Eagle Pass is reiterated here. Laramie is 

stated to occur in the valley of the Nueces also. The name Eagle Pass 

beds is used for the beds containing the coal at Eagle Pass.

1891. HILL (R. T.). Notes on the Texas-New Mexican region: Bull. Geol. Soc. 

America, Vol. Ill (proceedings of the Washington meeting), pp. 85-100.

Pages 93 to 95 contain a description of the Rio Grande embayment.

1892. BUMBLE (E. T.). Notes on the geology of the valley of the Middle Rio Grande: 

Bull. Geol. Soc. America, Vol. Ill, April, 1892, pp. 219-230.

Dumble describes and discusses the section from Del Rio, Valverde 

County, to Webb bluff, in the northern part of Webb County, and 

correlates the Rio Grande and the Colorado River section.

1892. HILL (R. T.). On the occurrence of artesian and other underground waters 

in Texas, New Mexico, Indian Territory, etc.: Final Reports of the Artesian 

and Underflow Investigations of the U. S. Department of Agriculture.

Accompanying this report is a map showing the general geologic 

and topographic features of the State. In the text there is a description of the topography of the region. The southern extension of the 

Edwards Plateau and its termination by the Balcones fault escarpment, 

which runs east.and west, a little north of a line joining San Antonio 

and Del Rio, is also described. At the foot of this escarpment is the 

vast level plain which Hill designated the "Rio Grande embayment." 

Hill states that this plain is covered to a very great extent by surface 

gravel. The following pages- contain, statements concerning the Middle Rio Grande region: 58, 63, 65, 66, 67, 68, 74, 76, 88, 91, 92, 119, 

and 123 to 125.

1892. DUMBLE (E. T.). Report on the brown coal and lignite of Texas: Geol. Survey 

of Texas.

On the map accompanying this report several outcrops of coal in the 

Rio Grande region are indicated. Pages 137 to 139 contain a description of the section of the Eocene from a point on the Rio Grande 3 

miles below the northern boundary of Webb County to Laredo.

1892. McGEE (W J). The Lafayette formation: Twelfth Ano. Rept. U. S. Geol. 

Survey.
VAUGHAN.] LITERATUEE. 71

Reference is several times made in the text to the Rio Grande 

region. PI. XXXVIII shows the areal distribution of the Lafayette 

and Columbian formations of southeastern United States, and represents the upland gravel of the Rio Grande region as Lafayette. 

1892. DUMBLE (E. T.). See Second Kept, of Progress Texas Geol. Survey, pp. 7-19.

Contains some general notes.

1892. COMSTOCK (Theo. B.). See Second Kept, of Progress Texas-Geol. Survey, 

pp. 43-54. '

Contains notes on the region.

1892. TAFF (J. A.). See Second Rept. of Progress Texas Geol. Survey, pp. 70-77.

1893. HILL (E. T.). The Cretaceous formations of Mexico and their relations to 

North American geographic development: Ain. Jour. Sci., 3d series, Vol. XLV.

"Opposite Del Rio, Texas, the Exogyra arietina zone of the Denison beds of the Washita division extends far into Mexico." Pages 

320 to 323 give a discussion of the relations existing between the Upper 

Cretaceous and the Eocene deposits in the Texas-Mexico region from 

Eagle Pass to Laredo, and the areal distribution of the formations. 

On page 321 is the following statement: "The Montana-Laramie 

Eocene portion of the formation occupies the vast synclinal basin of 

the Rio Grande, east of the great bend, which I have termed the Rio 

Grande embayment, outcropping beneath the detrital deposits of late 

Tertiary and Pleistocene age."

Two maps accompany this paper. The first, fig. 2, gives the distribution of known Cretaceous outcrops in Mexico and adjoining portions 

of Texas. The second is a " Geologic outline of northern Mexico, 

showing relations of Atlantic Coastal Plain, Cordilleran and Great 

Plains region." The topography of this map is modified from the 

map of the Mexican International Railway. It shows the vast distribution of the Tertiary gravel.

1894. HILL (R. T.). Geology of parta of Texas, Indian Territory, and Arkansas 

adjacent to Red River: Bull. Geol. Soc. America; Vol. V, March, 1894, pp. 

297-338.

On Plate XII a columnar section of the Cretaceous at Del Rio is 

given. The presence of Caprina limestone, Fort Worth limestone, 

and Exogyra cvrietina clays is represented.

1894. HARRIS (G. D.). Tertiary geology of southern Arkansas; Ann. Rept. Geol. 

Survey Arkansas, 1892, Vol. II.

Page 34 contains notes on Eocene fossils along the Rio Grande.

1894. DUMBLE (E. T.). The Cenozoic deposits of Texas: Jour, of Geology, Vol. II, 

pp. 549-567.

On page 550 the occurrence of Midwayan Eocene fossils on the Rio 

Grande, near the Webb-Maverick county line, is mentioned. Pages 

560 to 562 are devoted to a description of the Reynosa division, which
72 EIO GRANDE COAL FIELDS OF TEXAS. [BULL. 164.

Dumble correlates with the upland gravel deposit of the Rio Grande 

embayment, previously mentioned by Hill and Penrose.

1895. DUMBLE (E. T.). Cretaceous of western Texas and Coahuila, Mexico: Bull. 

GeoL Soc. America, Vol. VI, April, 1895, pp. 375-388.

Pages 383 and 384 contain references to the geology of the region

of the Rio Grande Plain.

.t

1895. DUMBLE (E. T.). The soils of Texas; a preliminary statement and classification: Texas Acad. Sci., pp. 25-60.

Several allusions are made to the geology of the Rio Grande region, 

and data on the soils is given/

1896. HARRIS (G. D.). The Midway stage: Bulletins American Paleontology, 

Vol. I, No. 4. . .

Pages 13 and 14 contain a discussion of the basal Eocene along the 

Rio Grande.

1897. HARRIS (G. D.). The Lignitic stage; Part I, stratigraphy and pelecypoda: 

Bulletins American Paleontology, Vol. II, No. 9, pp. 198, 199 (6, 7).

In this paper Harris discusses the probable occurrence of the Lignitic 

Eocene (Chickasawan) along the Rio Grande.

1897. VAUGHAN (T. Wayland). The asphalt deposits of western Texas: Eighteenth 

Ann. Kept. U. S. Geol. Survey, Pt. V (continued); Mineral Resources of the 

United States, 1896, Nonmetallic products, except coal, pp. 930-935.

This paper describes the occurrence of asphalt in the Brackett quadrangle and along the Nueces River in southern Uvalde County (Uvalde 

quadrangle).

1898. HILL (R. T.) and VAUGHAN (T. Wayland). Geology of the Edwards Plateau 

and Rio Grande Plain adjacent to Austin and San Antonio, Texas, with reference 

to the occurrence of underground waters: Eighteenth Ann. Kept. TJ. S. Geol. 

Survey, Pt. II, pp. 199-321.

Contains numerous references to the geology of the Rio Grande 

region below Del Rio.
II. THE SAN CARLOS COAL FIELD OF TRANS-PECOS TEXAS AND 

ADJACENT PORTIONS OF THE VIEJA MOUNTAINS.

INTRODUCTORY NOTE.

In August, 1895, the writer was requested by Mr. Robert T. Hill, 

geologist in charge of the Texas division of the United States Geological Survey, to go to the newly opened coal mines in the vicinity of 

San Carlos, Presidio County, Texas, in order to ascertain the geologic 

position o'f the coal, and if possible obtain samples of it for the' Atlanta 

Exposition. Mr. T. W. Stanton accompanied the writer, for the purpose of studying the paleontology, and to a large extent the field work 

was carried on jointly. Mr. Stanton furnished the determinations of 

the fossils collected and his conclusions regarding the horizons to which 

they belong. Dr. E. C. E. Lord kindly made a careful study of all the 

lithologic material collected, and the results of his investigations are 

given in his report on the igneous .rocks from the vicinity of San Carlos 

and Chispa, Texas, which is a part of this bulletin (pp. 88 to 95).

While at San Carlos numerous courtesies were received from the 

following officers of the San Carlos Coal Company: Mr. S. A. Johnr 

son, president; Mr. Charles Seibert, general manager, and Mr. John 

J. Maloney, mine superintendent; also from Mr. G. N. Marshall, chief 

engineer of the Rio Grande Northern Railroad, and Mr. J. E. van 

Riper, civil engineer. To these gentlemen our thanks are extended.

GEOGRAPHIC POSITION OF LOCALITIES STUDIED.

(PI. VI.)

Chispa and San Carlos, the places near which our studies were made, 

are situated in Jeff Davis and Presidio counties, respectively, almost 

in the heart of the mountainous region of Trans-Pecos Texas. Chispa 

is on the Southern Pacific Railroad, about 150 miles southwest of El 

Paso. San Carlos is 26 miles, by rail, almost due south of Chispa, at 

the terminus of the Rio Grande Northern Railroad, a short road 

branching from the Southern Pacific Railroad at the latter place. The 

work on this branch road, which was far advanced at the time the 

region was visited, has been completed.

Most attention was given to the Vieja Mountains, which are a portion of a range with a trend from west of north to south of east. 

Beginning at the southern end of this range and going north, it com73
74 EIO GKANDE COAL' FIELDS OF TEXAS. [BULL. 164.

prises the following mountains: The Chinati, Vieja, Van Horn, Carrito, Diablo, Prieta, and Cornuda. Eagle Mountain lies a short 

distance west of the axis of the chain, opposite Bass Canyon. The 

Sierra Blanca are isolated peaks northwest of Eagle Mountain. West 

of Sierra Blanca is the Quitman system, with a NW.-SE. trend. 

Beginning at its southeast end and going northwest, it is composed of 

the Quitman, Malone, Finlay, and Hueco, mountains. Still farther 

west are the Organ Mountains, whose axis extends from north to 

south. East of the Vieja Mountains are the higher ranges, known as 

the Guadalupe, Davis, and Chisos groups, which constitute the eastern 

front of the whole Trans-Pecos mountain region.

The exact localities studied were: (1), The isolated peak, belonging 

to the Vieja Mountains, 6 miles west of south from Chispa; (2) the 

vicinity of San Carios; (3) the western side of the railroad from 

Chispa summit (the pass between the Van Horn and Vieja mountains) 

to a point 13 miles from Chispa, going southward toward San Carios.

LITERATURE.

Very little has been written concerning this area. W. H. von Streeruwitz has published a few remarks in the reports of the Geological 

Survey of Texas. In the fourth annual report of that survey,'A. 

Osann makes some interesting notes on the igneous rocks. On pages 

3.86 and 387, Vol. VI of .the bulletins of the the Geological Society of 

America, E. T. JDumble gives a general section of the Vieja Mountains 

at San Carios.

TOPOGRAPHY AND STRUCTURE.

For the details of the topography the Chispa and San Carios topographic sheets of the United States Geological Survey must be consulted.

Many geologists have noted in Trans-Pecos Texas the peculiar 

desert valleys or basins, filled with detritus, lying between the mountains of the region, and the abrupt manner in which the mountains 

rise from them. (PI. VI.) Chispa, at an altitude of 4,082 feet, is 

situated in such a basin valley, which is bounded on the south and west 

by the Vieja and Van Horn mountains, respectively, and on the north 

and east by outlying westward members of the Davis ranges.

About 6 miles southwest of Chispa there is a saddle or pass, known 

as Chispa Summit, which separates the Vieja Mountains on the southeast from the Van Horn Mountains on the northwest. The.altitude 

of this saddle is a little less than 4,250 feet. On its southern slope 

Van Horn Creek rises. This creek flows through a valley,* some 5 or 

6 miles wide, in a general southerly direction, into the Rio Grande. Its 

elevation where it passes from the Chispa quadrangle is less than 3,300 

feet. On its east side, and subparallel to it, are the Vieja Mountains, 

the altitude of whose crest varies from 5,250 to a little over 6,000 feet;
U. S. GEOLOGICAL SURVEY BULLETIN No. 164 PL. VI

TOPOGBAPHY OF THE SAN CABLOS BEGION SHOWING LOCATIONS DESCRIBED

Scale

LITH. BYA.HOEN&CO..BALTIMORI:
VAUQHAN.] . STBUOTUBB OF SAN CAELOS FIELD. 75

on its western side, subparallel to it, is a lower range of unuained 

mountains whose altitude rarely exceeds 4,250 feet.

For a considerable portion of its length the rocks on the east side 

of this stream dip toward the Vieja Mountains, and on the west side 

toward the range on the west. Therefore this creek frequently flows 

along the very summit of an anticline, of which the Sierra Vieja represents the eastern limb and the unnamed range to the west the western limb. On the southern side of Chispa Summit the dip is southerly. About 2 miles southwest of the summit, and subparallel to 

the Rio Grande Northern Railroad, there is a narrow ridge with an 

altitude of approximately 4,500 feet, or some 500 feet above the valley. This ridge is composed of Lower Cretaceous limestone. Along 

its eastern front there is a fault, with a north-south strike and an 

easterly downthrow, by which the Benton shales have been brought 

down about 200 feet below the top of the Edwards (Caprina) limestone, 

so that now the shales are exposed from the foot of the ridge to a line 

east of the railroad.

San Carlos, with an altitude.of about 3,988 feet, is situated in the 

basin valley of San Carlos arroyo and is almost entirely enclosed by 

mountains belonging to the Vieja system. The highest point of the 

Vieja Mountains, about 7 miles east of the town, is 6,470 feet. (Pis. 

VII, VIII, and IX.) The summit of the mountain is a little more than 

2,700 feet-above the valley of San Carlos arroyo. The basin is almost 

completely surrounded by what the inhabitants call rim rock quartzpantellerite which occurs east, south, west, and north of the town. 

Around the border of this basin the rocks dip away from the center, 

those along the eastern side dipping toward the east, those on the 

southern side dipping toward the south, and those o'ri the western and 

northern sides dipping west and north, respectively. The geologic 

structure is, therefore, that of a quaquaversal fold or an anticlinal 

dome. San Carlos arroyo has cut out the top of the dome and made 

its bed across the southwestern corner, flowing in a southerly directioninto the Rio Grande. Just west of San Carlos there is a great fault, 

pointed out by Dumble, 1 striking north and south, with a westerly 

downthrow of over 2,000 feet, and bringing the rim rock "nearly to 

the level of the valley."

Along the foot of the mountains on the west side of San Carlos 

arroyo, and within a distance of three-fourths of a mile, are five.springs, 

known as Newman's springs. The largest has been gaged, and accordIng to Mr. S. A. Johnson furnishes a supply of 15,000 gallons of 

water a day. Mr. Johnson stated that he believed when all the springs 

are cleaned out that they will supply 40,000 to 50,000 gallons a day. 

The water is of excellent quality.

i Bull. Geol. Soc. America, Vol. VI, p. 387.
76 EIO GBANDE COAL FIELDS OF TEXAS. [BULL. 164.

SECTIONS STUDIED AND NOTES THEREON. 

PEAK NEAR CHISPA.

Section of peak belonging to the Vieja Mountains 6 miles west of south of Chispa.

(PI. VII; PL XI, fig. 1.) '

Feet.

1 23. Massive reddish porphyritic rhyolite, with some fragmental material ..... 40

22. Clay.................................................................. 30

21. Ked sandstone.....................................^............ ...... 60

20. Grayish rock (probably pyroclastic rhyolite) overlain by clays ........... 40

19. Conglomerate and clays.............'........................-.......... 80

1 18. Rhyolite breccia, white, gray, green, or pinkish in color.................. 100

1 17. Thick ledges of hard whitish or gray rock, greenish in upper portion' (rhyolite breccia).......................... ............................... 30

16. Conglomeratic sandstone and clays...................................... 50

15. Whitish rock, probably rhyolitic ........................................ 34

14. Clay ?...................--... ..........:....-_:.._................. 3

1 13. Ehyolite breccia, groundmass altered to calcite ........................... 3

1 12. Ehyolite breccia, gray in color, containing considerable basaltic material.. 2 

1 II7 . Amygdaloidal facies of 11, contains many cavities infiltrated with chlorite,

calcite, zeolites, etc .................................................. 10

From 11' small stringers run into 12, and there are both necks and small 

masses of the amygdaloid in 12. The rhyolite breccia at the contact is 

very much indurated, while at .a short distance above the contact it has a 

much looser texture. 

1 11. Dense, almost black, basalt with feldspar phenocrysts.................... 65

1 10. Fine-grained pink rhyolite breccia, containing considerable basaltic-material. 6 

9. Fine-grained material (pyroclastic?).................................... 60

8. Conglomerate, underlain by clay......................................... 20

7. Sandstone pebbles at base, grading into dark vermilion-colored clays, conglomerate again above the clay ....................................... 60

6. Very coarse conglomerate, containing pebbles of slate, red quartzite, greenish quartzite, cherty limestone, and red eruptive rock.... .1............ 50

(Just below 6 a much-decomposed greenish eruptive rock was seen, but 

it may not have been in place.) 

1 5. Massive reddish rhyolite, containing in a portion of the bed vesicles that

have been filled with chalcedony ..................................... 20

4. Sands and clays .................-...........-........:................ 40

3. Sands and clays, w$h occasional lenticular masses of conglomerate........ 60

2. Lenses of conglomerate................................................. 1-5

1. Laminated sandstone and clays, clays very sandy. The color of the rock is 

greenish, due to the presence of considerable quantities of chlorite...... 40

A small dike, striking east and west and cutting the lower part of 

the above series, was observed. This dike is probably of basaltic 

material.

The dip where the above section was made is 4°+, S. 50° E.

This section can be simplified and described as consisting of alternating beds of sedimentaiy rocks and lava flows, or beds of rhyolitic

1 Determined from a study of thin sections by Dr. Lord.
BULLETIN NO. 164 PL. VII

A MOUNTAINS, LOOKING SOUTH FROM CHISPA. 

k is the one of which the section described on page 76 was made.
VATJGHAN.] SECTIONS IN VICINITY OF SAN CARLOS. 77

pyroclastic material. The basalt occurs at about the center of the 

section, and apparently is intrusive into the bed immediately overlying it. The reasons for this conclusion are given in the discussion 

of No. 11' of the preceding section.

In the sediments interbedded with the lavas and pyroclastics no 

fossils were found, and we could not determine the precise age of the 

series. For these interbedded lavas, pyroclastics, and sediments 

the name Vieja series is proposed, from the Vieja Mountains, where 

they are well exposed and where they were studied.

SECTIONS IN THE VICINITY OF SAN CARLOS.

N

Section of the Vieja Mountains from the San Carlos arroyo, 1 mile below San Carlos, to 

the top of Hie mountain east of the town.

(PL VIII; PI. XI, fig. 2.)

Feet. 

22. Rim rock, a greenish-yellow rock, containing large phenocrysts of anorl thoclase feldspar, determined by Dr. Lord to be quartz-pantellerite.. 400-600 

! ' 21. Variegated sandstones and clays, and probably rhyolite breccias ...... 500

(It was not possible to examine this part of the section carefully, so 

"^ the notes are very meager.)

20. Grayish and purplish clays, etc., approximately..................... 500

19. Yell&w clays, or soft yellow sandstone, with occasional carbonaceous

seams............................................................. 150

18. Carbonaceous seam ................................................ 20

17. Yellow or purplish clays, with ledges of soft yellow sandstone and

occasional carbonaceous seams.................................... 250

16. Coarse, soft, yellow, cross-bedded sandstone........ ................ 25

15. Yellow clay, with two or three carbonaceous seams .................. 20

14. Coarse, soft, yellow, laminated sandstone in ledges .................. 30

13. Yellow clay, carbonaceous at base.................................. 6

12. Coal.............................................................. If

11. Impure coal........................................................ 3

10. Carbonaceous shale ................................................ 1

9. Purple clays. ....................................................... 4

8. Coal.............................................................. 1$

7. Purplish clays..................................................... 4

6. Soft yellow sandstone and argillaceous sandstone..................... 110

5. Yellow or brown sandstone; 40 feet above base limestone concretions;

a few poor fossils, mostly Exogyra fragments...................... 90

4. Ledge of brown sandstone, containing well-preserved specimens of a

large Inoceramus (J. oblongus Meek) in great abundance........... 4 or 5

3. Laminated brown or yellowish fossiliferous sandstone; about 20 feet

below the top there is an indurated ledge containing many oysters.. 250 

' 2. Clay, with calcareous concretions which contain many well-preserved

iossils........................................................... 40

1. Thinly laminated clays weathering yellowish, capped by soft, yellow,

laminated sandstone.............................................. 20

The total thickness examined, a little less than.................. 2,700
78 EIO GKAJSTDE GOAL FIELDS OF TEXAS. [BULL. 164. ;

The following is Bumble's section published in the Bulletin of the 

Geological Society of America, and previously alluded to:

General section of Vieja Mountains near San Carlos.

 _ .' Feet.

1. Lava'.flow, rim rock of mountain..................... ^............... 200-300

2. Sandstones of various colors, interbedded with calcareous clays and volcanic ash.......................................................... 550

3. Conglomerate, resting unconforrnably on No. 4......................... 1-16

4. Lava flow, apparently conformable on No. 5........................... 50

5. Interbedded brown and red sands, purple shales, and yellow quartzitic

sandstone.......................................................... 500

6. Gray and purple shales, with thin strata of sandstone.................. 200

7. Coal shales, with beds of laminated sands and two seams of coal, highly 

f ossilif erpus -between and below the coal seams .........................

8. Interbedded sands and sandstones, some highly calcareous; f ossilif erous..

9. Shales with concretions of clayey limestone containing fossils...........

This gives a total thickness of over..................: ................ 2,800

The general character of the writer's section from San Carlos arroyo 

to the top of the mountain is almost the same as Dumble's. No. 22 of 

the writer's section equals No. 1 of Dumble's; No. 21 of the writer's 

section equals No. 2 of Dumble's.

The conglomerate bed and lava flow, 3 and 4 of Dumble's section, 

were not seen in going up the mountain at San Carlos. A conglomerate 

occupying the same stratigraphic position as Dumble's No. 3 was found 

near the base of Gettysburg Peak, a .section of which will be described 

later. Huge bowlders, evidently derived from the disintegration of a 

conglomerate, are very abundant on the low hills in the valley of the 

San Carlos arroyo.

No. 20 of the writer's section equals for the greater part Nos. 5 and 

6 of Dumble's; Nos. 19 to 15 .equals .No. 7 of Dumble's;. Nos. 4 and 3 

equals No. 8 of Dumble's; Nos. -2 and 1 equals the upper part of No. 

9 of Dumble's. -The aggregate thickness of-the two sections is practically the same.' As definite lines of demarcation between the sedimentary beds could not be found; of course the exact details could not be 

expected to agree. No fossils were found between the coal seams. 

The minimum thickness given for the rim rock was determined, 

instrumentally, by Mr. C. C. Basse.tt, who made the San Carlos topographic map.

Fossils from section of Vieja Mountains from San Carlos arroyo, 1 mile below San Carlos, 

to top of mountain east of town.

Fossil from No. k (field No.-SOl).1

Inoceramus oblongus Meek, possibly identical with I. cumminsi Cragin, but 

these specimens do not have the characteristic' posterior plication on 

which that species was founded.

1 The flejd numbers are those used by Mr. Stanton.
U. 8. GEOLOGICAL SURVEY BULLETIN NO. 164 PL. VIII

VIEW OF VIEJA MOUNTAINS, LOOKING EAST FROM.SAN CARLOS. 

The quanz-pantellente forms the top of the mountain.
VAUGHAN.] SECTIONS IN VICINITY OF SAN CARLOS. 79

Fossils from No. S (field No. SOS). 

Pecten sp. 

Veniella sp.

Cardium carolinese Conrad? 

Cardiurn sp. Cf. tenuistriatum Whitfield. 

Cyprimeria sp., same as that in No. 2. 

Mactra sp., related to M. warreneana M. & H. 

Mactra sp. 

Corbula sp. 

Dentalium sp. 

Gyrodes petrosa (Morton).

Anchura sp., large species related to A. abrupta Conrad. 

Pugnellus sp. 

Volutomorpha sp.

Rostellites sp. , 

Pyropsis trochiformis Tuomey?, apparently identical with tlie New Jersey

form doubtfully referred to this species by Whitfield. 

Placenticeras guadalupse (Roemer). Bare.

Fossils from No. 2 (field No. 297).

Exogyra costata Say, a variety intermediate between this species and E.

ponderosa Roemer. 

Pecten sp. - Avicula linguiformis E. & S. 

Inoceramus cripsi var. barabini Morton. 

Inoceramus proximus Tuomey. 

Inoceramus vanuxemi M. & H. 

Pinna sp. Cf. P. laqueata Conrad. 

Cucullsea sp. 

Veniella sp.

Cyprimeria sp., related to C. alta Conrad. 

Pholadomya sp. 

Turritella trilira Conrad var. 

Anchura sp. 

Gyrodes sp. 

Strepsidura ? sp. 

Nautilus dekayi Morton.

Placenticeras guadalupse (Roemer). Abundant. 

Schloenbachia delawarensis (Morton). 

Baculites asper Morton. 

Baculites ovatus Say ? 

Hamites ?, fragments of two species. 

Scaphites sp., related to S. nodosus, but a distinct species.

Detailed section through coal seams at tunnel of mine No. 4 of San Carlos Coal Company, 

. on west slope of the Vieja Mountains, about # miles east of San Carlos.

(PI. XI, fig. 2a.)

In. Ft.

9. Clay, thickness variable...............;............................... 13 to 3

8. Upper coal seam (coal noncoking) ..................................... 10 to 3

7. Clay, thickness variable.........................'...................... 6 to 2

6. Sandstone, thickness variable.......................................... 2 to 7

5. Clay, sometimes present.

4. Lower coal seam, thickness variable ................................... 2 to 3
80 EIO GEANDE COAL FIELDS OF TEXAS. [BULL. 164.

The lower limit in thickness occurs over a very small area; the average thickness 

is about 2 feet. In this seam a binder occurs. The binder consists of two thin 

seams of sand, and varies in thickness from half an inch to 2 inches. Between 

the seams of sand is a thin coal seam about half an inch thick. Of this coal seam 

where examined: 

a. Upper 9-inch does not coke. 

b. Nine inches just above binder coking. 

c. Binder.

d. Below binder, 9 inches, coal all coking. 1 

3. Carbonaceous shale. ......_....................'._.._......_......... 1 to 3 in.

2. Fire clay ........................................................... 2 ft.'2

I. Sandstone.

This section of the coal corresponds to Nos. 13 to 6, inclusive, of the 

general section of the mountain.

Along the side of the mountain the usual dip is 5° to 7° (though it 

may sometimes be more or less), and the strike is N. 35° to 50° E. i

Section in arroyo northeast of shaft of San Carlos Coal Company, -2 miles east of south of

San Carlos.

(PL XI, fig. 26.) 

. ^ . Feet.

II. Soft yellow sandstone. ................................................... 10

10. Yellow clays........--...--.,.--....-----------:--.-----.--.-----..-.--- 10

9. Ledge of soft yellow sandstone. ..................... .................... 15

8., Clay.

7. Coal, upper seam.

6. Clay.

5. Coal, lower seam.

4. Soft yellow sandstone. ................................................... G

3. Bluish clay, with fossils, Cyprimeria, Inoceramus, Exogyra, etc.. .......... 35

2. Layer of clay containing many limestone nodules and fossils. ............... 1

1. Clay.

Above the soft sandstone (No. 11) are two other prominent sandstone ledges, about 30 feet apart, the upper of which is conglomeritic.

The strike of the rocks at the foregoing exposure is southwest and 

northeast, dip 20° to 30° SE.

Fossils from No. S (field No. 

Ostrea sp. 

Exogyra costata Say.var. 

Inoceramus sp., fragments of a large form. 

Trigoniasp. 

Cyprimeria sp., the same as for field Nos. 297 and 298.

OVERTURNED FOLD NORTH OF SHAFT OF SAN CARLOS COAL COMPANY.

A short "distance north of the shaft of the San Carlos Coal Company 

there is a small overturned fold accompanied by an overthrust fault. On 

the overthrust side 01 the fault a fossilif erous horizon is exposed, but it

1 The information concerning what part of the coal seam would coke was furnished by Mr. Maloney, 

mine superintendent. Samples of the coke were furnished by the mine officials. 

2 Or more.
VIEW OF GETTYSBURG PEAK FROM SA
VAOGHAN.] SECTIONS IN VICINITY OF SAN CARLOS. 81

»

was not determined which of the horizons it represents, i. e., whether 

the one just below the coal or the one at the .base of the section of the 

mountain.

Fossils from fault north of shaft of San Carlos Coal Company (field No. 300}.

Ostrea elegantula Newberry. 

Exogyra costata Say.var. 

 Inoceramus proximus Tuoniey. 

^Cyprimeria sp. 

Cardiuin alabamense Gabb. 

Rostellites sp. 

Gyrodes sp.

Gyrodes crenata Conrad? 

Schloenbachia delavvarensis (Morton). 

Placenticeras guadalupse (Roemer).

SANDS AND CLAYS.

From observations iii the entries at the shaft of the San Carlos Coal 

Company and in mine No. 4, it was ascertained that the clays and 

sandstones, which, are yellowish on the surface, are of bluish color 

before exposure to the influence of weathering.

SA,N CAKLOS AND ARROYO ABOVE.

Near the store at San Carlos (field No. 296) were collected Placenticeras f/uadalupCG (Roemer) and Schoenbachia delawarensis (Morton).

Along the San Carlos arroyo, above San Carlos, in the sandstone 

and clays above the coal, a few fragmentary vertebrate remains were 

collected, which have been examined by Mr. F. A. Lucas. He states 

that they include a fresh-water turtle and several dinosaurian bones of 

Cretaceous type.

Section of Gettysburg Peak, 1 mile north of San Carlos.

(PI. IX; PI. XI, fig. 2c.)

Feet.

3. Quartz-pan tellerite ...................................................... 180

2. Ledges of variegated rock resembling sandstone, but probably composed

largely of pyroclastic rhyolite .......................................... 300

1. Conglomerate bed.

Resume of San Carlos section. a 

Quartz-pantellerite. 

Vieja series:

5. Ledges of variegated rock, probably largely pyroclastic.

4. Conglomerate bed. 

San Carlos formation:

3. Sandstone and clays above coal, containing Cretaceous vertebrates.

2. jCoal horizon.

1. Sandstone and clays below the coal, containing three or four horizons of 

invertebrate fossils.

For the sandstones and clays containing the coal, below the Vieja 

series to the base of tha San Carlos section, the name /San Ca/rlos formation is proposed. 

Bull. 164 6
82 EIO GKAKDE COAL FIELDS OF TEXAS. 

AGE OF FOSSILS BELOW THE COAL.

Stanton makes the following notes regarding the fossils from the 

San Carlos region:

The invertebrate fossils from the neighborhood of San Carlos (Nos. 296-307) come 

from several different horizons ranging through a considerable thickness of strata, but 

they all clearly belong to one fauna. Essentially the same list of species was identified in 1894 for Mr. E. T. Bumble, who had visited the region with Mr. Cummins. 

The list, with a note on the relationship of the fauna, was published by the former. 1 \ 

There seems to be no reason for changing the opinion there expressed, that the horizon 

is beneath the Ripley and above the Austin chalk that is, it is equivalent to a part < 

of the Taylor (Exogyraponderosa) marls of central Texas and of the Pierre of the 

western interior region. It is not now possible to fix the horizon more definitely.

The same fauna occurs near Presidio, Texas, on the Mexican side of the river, 

where its relations to the underlying beds are more clearly shown. There it is underlain'by a series of Upper Cretaceous shales with an estimated thickness of 3,000 or 

4,000 feet, in the lower part of which Inoceramus labiatus, the characteristic fossil of 

the Benton, was found.

The age of the coal is thus definitely determined to be Upper Ore- \' 

taceous, because Upper Cretaceous fossils were found both above and ' 

below the seams. The Pierre fauna occurs almost in contact with the 

lower^seam, from which it would seem that the coal should be referred 

to the Pierre beds.

A point of special interest is that by means of the fossils here, collected a part at least of the Taylor (Exogyraponderosa) marls are 

referable to the lower member of the Montana division of the northwestern interior Cretaceous region. 8 (

BRACKS CANYON. '

(PI. X.)

About a half mile west of San Carlos is the eastern end of a narrow 

gorge, known locally as Bracks Canyon, which cuts across a mass of 

the quartz-pantellerite. This gorge is about one-fourth of a mile long, 

from-15 to -20-feet wide.at the bottom,.250 feet deep, with nearty perpendicular walls, and extends in an east-west direction. It is one of «p 

the drainage channels from the San Carlo's Basin, the divide between it 

and San Carlos arroyo being within the San Carlos Basin. It is a 

question whether this^canyon has been cut by erosion or is simply a 

cleft in the rock, but it is apparently the bed of a stream whose head 

waters have been captured by San Carlos arroyo.

In the middle portion of this canyon a large mass of rhyolite breccia \, 

was found included in the pantellerite. Just beyond the western end of 

 the canyon a mass of baked clay was found, but owing to the limited time 

at our disposal it was impossible to decide whether the clay was or was 

not included in the pantellerite. It did not appear to be an inclusion.

Jfiull. Geol. Soc. America, Vol. VI, April, 1895, pp. 386-387.

=Dr. C. A. White, in Bull. 82 of the U. S. Geological Survey, p. 160, although he does not state it 

explicitly, evidently intends to include the Taylor (Exogyra pondcrosa) marls in the Montana. Mr, 

E. T. Dumble, in his paper already frequently quoted, refers these beds to the Montana.
U. S. GEOLOGICAL SURVEY BULLETIN NO. 16* PL. X

ENTRANCE TO BRACKS CANYON, EASTERN END, SAN CARLOS.
VAUGHAN.] NOTES ON 6 AN CAELOS SECTIONS. 83 

GEOGRAPHIC DISTRIBUTION OF QUARTZ-PANTELLERITE.

From the peak 6 miles west of south from Chispa one can, upon 

looking east, see a very thick sheet of rock above the rocks which form 

the peak. Going south-along Van Horn arroyo, this sheet can be 

traced with the eye, and is seen to form the top of the mountain the 

entire distance to San Carlos. Messrs. Bassett and Chapman, who 

during the field season of 1895 made the San Carlos topographic 

sheet, noticed this peculiar rock, and have furnished additional observations in regard to its distribution. It extends south and east of San 

Carlos for many miles. (PL VIII.) As the area covered by the pantellerite has not been mapped geologically, it is not possible to state 

what extent of territory was originally covered by that enormous sheet, 

but from present knowledge it was certainly many hundred, possibly 

several thousand, square miles.

CORRELATION OF THE CHISPA AND SAN CARLOS SECTIONS.

So great a variety of volcanic products as was observed south of 

Chispa was not seen at San Carlos, bat taking the pantellerite and the 

rocks immediately underlying it as starting points for a comparison, 

there can be no doubt that all of the section studied in the peak south 

of Chispa is above the coal horizon. The beds at Gettysburg Peak, 

near San Carlos, from and including the conglomerate bed to the base 

of the pantellerite, certainly represent, in part at least, the Vieja series.

The stratigraphic relations existing between the Vieja series and the 

underlying San Carlos beds were not discovered. Whether two series 

of beds are comformable or are separated by an unconformity was not 

ascertained.

TIME OF THE VOLCANIC OUTBURSTS.

Durable, 1 in his paper on the. Cretaceous of Western Texas and Coahuila, Mexico, states: "Since no erosion was observed in the bed 

immediately underlying the first lava flow, this lava of the Vieja Mountain is * * * seemingly of Ponderosa age." It may be true that 

the outbursts occurred during the time in which the Taylor (Exogyra 

ponderosa) marls were deposited, but neither Dumble's nor our own 

observations were sufficiently extensive to solve the problem. It should 

be stated that the interbedded f ragmental rhyolites and sediments have 

been subjected to erogenic movements, showing that the faulting and 

folding have taken place since volcanic activity ceased.

DIKES.

Two systems of dikes were noted, as pointed out by Dumble. As 

no collection of the dike .rocks was made, this subject is passed without 

further remarks.

ifiull. Gcol. Soc. America, Vol. VI, p. 387.
84 EIO GEANDE COAL FIELDS OF TEXAS. [BULL. 164. 

STRATA BELOW THE SAN CARLOS FORMATION.

About 6i miles from Chispa, along the Rio Grande Northern Railroad, there is an exposure of thinly laminated bluish calcareous shale, 

containing Inoceramus labiatus, Placenticeras sp., and Ptychodus sp. 

These shales represent the Eagle Ford shales and the Valverde flags 

of eastern and central Texas, and the Benton shales of the western 

interior region.

Running subparallel to the railroad, on its west side, is a ridge 300 or 

400 feet above the roadbed. Along the eastern foot of this ridge the 

Benton shales are exposed; they have a dip of Y° or 8° S. Three 

hundred feet above the railroad, near the summit of the ridge, a limestone with a rather steep westerly dip, and containing a fauna apparently of Washita age, is exposed. The Benton shales have been fa'ulted 

several hundred feet below the Washita.

A section up the side of this ridge was as follows: "

Section of ridge about 6 1-% miles from Chispa, on Rio Grande Northern Railroad.

(Pi. XI, fig. 3.)

Feet.

4. Alternating ledges of hard nodular or soft nodular limestone, the nodules containing numerous fossils.

3. Flaggy brown sandstone.

3. Ledges of massive limestone, hard, bluish, weathering brown, much jointed, 

weathered surface very rough, fossiliferous. Contains silicious or cherty 

nodules in which were found Kadiolites, Eequienia, Monopleura, and Pholadomya.............................................................. 25

1. Nodular, argillaceous limestone, fossiliferous, resembling in lithologic aspect 

the Comanche Peak limestone of central Texas.

The following fossils were collected from the foregoing section :

Fossils from No. 4 .(field No. 803). 

Enallaster texanus Koemer.

Holectypus planatus Eoemer ? Kingena wacoensis (Eoemer). 

Neithea texana Roerner. 

Cypricardia texana Eoemer? * 

Cinulia sp.

Chemnitzia ? sp. v 

Ammonites sp.

Apparently this fauna is of Washita age. Kingena wacoensis is usually a Washita species, though it also occurs in the Edwards limestone.

Fossil fr'om No. 2 (field No. SOSa). 

Ichthyosarcolitb.es anguis Eoemer? 

This bed is referred to the Edwards limestone.

Fossils from No. 1 (field No. SOSb). 

Gryphsea sp. ' 

Neithea texana Eoemer. 

Pleuromya knowltoni Hill? 

Turritella seriatim-granulata Eoemer? 

Tylostoina pedernalis Eoemer.
U. 8. GEOLOGICAL SURVEY BULLETIN NO. 164 PL. XI

25

22

21

20

IB

 '

'»/* sy-J^ar g v- £---

20

JFig.l.

16 

IS

'.3.

COLUMNAR SECTIONS IN THE VICINITY OF CHISPA AND SAN CARLOS.

Fig. I. Section of peak 6 miles west of south from Chispa. Scale, 32 feet to 1 inch. (See p. 76.)

Fig. 2. Section of Vieja Mountains in vicinity of San Carlos. Scale, 32 feet to 1 inch. (See p. 77.)

Fig. 2a. Section through coal seam at Tunnel Mine No. 4. Scale, 53 feet to 1 inch. (See p. 79.)

Fig. 26. Section through coal seam 2 miles east of south from San Carlos. Scale, 53 feet to 1 inch. CSee p. 80.)

Fig. 2c. Section of Gettysburg Peak. Scale, 32 feet to 1 inch. (See p. 81.)

Fig. 3. Section of beds below the San Carlos formation, as exposed on the south sfde of Chispa Summit. (See p. 84.)
VAUGHAN.] STRATA BELOW THE SAN OAELOS FORMATION. 85

From the presence of such a form as Tylostoma pedemalis, this bed 

is referred to the Fredericksburg division of the Comanche series, but 

no attempt is made to correlate it with any definite horizon.

Along the railroad, where it begins to climb Chispa Summit, a hard 

blue limestone, in thick ledges, is frequently exposed beneath the Benton shales. This limestone contains fossils, but no identifiable specimens were secured, except in one place, on a weathered slope, a specimen of Alectryonia ca/rmata Lam. was found. This limestone is 

apparently conformably overlain by the Benton shales, and occupies, 

with reference thereto, the same stratigraphic position as the Buda 

limestone of central Texas, but no distinctive Buda fossils were collected. 1 Neither was it discovered what underlies this limestone. 

Therefore, in spite of presumptive evidence in favor of it, any definite 

correlation with the Buda limestone would be premature. (PI. XI, 

fig. 3, Nos. 5 and 6.) "

The following summary of the general characters of the section 

below the San Carlos formation is given:

1. No exposures from the lowest outcrop of the San Carlos beds to 

near the base of the Benton shales were seen, but according to Stanton's observations in the vicinity of Presidio, Mexico, the intervening 

beds consist of shales.

2. The Benton shales overlie, apparently conformably, a hard blue 

limestone, probably the equivalent of the Buda limestone of central 

Texas.

3. What immediately underlies No. 2 was not seen. A limestone 

containing species of fossils characteristic of the Washita division, and 

representing a lower horizon than No. 2, was found. Below this 

limestone there is a stratum of brown sandstone probably 30 to 50 feet 

thick.

4. JBelow the sandstone mentioned were found ledges of limestone 

containing cherty nodules and a fauna characteristic of the Fredericksburg division.

EXTENT OF SA1ST CARLOS AND OTHER TRANS-PECOS 

TEXAS COAL FIELDS, AND CONDITION OF MINING.

The San Carlos coal basin is situated in the basin valley of the San 

Carlos arroyo, described in preceding pages. At the time of the visit 

to San Carlos, work was being prosecuted at two places. The first 

working was in a shaft 2 miles, in a straight line, south of southeast 

from San Carlos. This shaft was unfortunately sunk near a fault, and 

at that time the coal seam had not been found in the drift to catch it. 

Mr. Bassett, who was engaged during the summer of 1895 in making

1 Alectmjonia carinata occurs iu the Buda limestone and in the lower horizons of the Washita 

division.
86 EIO GKANDE COAL FIELDS OF TEXAS. [BULL. 164. '

the San Carlos topographic sheet for the United States Geological 

Survey, states that work in this shaft has been abandoned. The second 

working was along a slope on the side of the mountain, a little less 

than a mile and a half slightly south of east from San Carlos. It has 

been reported that the mine here has been abandoned. There are other 

outcrops of coal on the side of the mountain and along the courses of 

some of the arroyos in the basin.

Mr. G. N. Marshall, chief engineer of the Rio Grande Northern 

Railroad, informed the writer that coal also outcrops on the western 

slope of the Vieja Mountains, in the valley of Van Horn Creek, but 

that it had not been found in commercial quantities. The inference is 

that coal will be found here, as lower geologic horizons are exposed 

along that creek and between it and the mountain.

Coal has been reported from several other localities in Trans-Pecos 

Texas, but so far as ascertained they have been neither prospected nor 

investigated. These,localities are: El Paso County, 1 Eagle Springs, 2 

between Sierra Barda and the Rio Grande, 3 and between Alpine and 

Paisano Pass.* Mr. R. T. Hill, who has recently made an expedition 

into the Great Bend country of the Rio Grande, furnishes the following note: "On the east and south side of the Chisos Mountains there 

are extensive areas of the Montana formation in which there are 

coal beds of unknown value."

Although the coal fields of western Texas have been little explored, 

there are indications that there are several occurrences of poor coal in 

the region.

The Cretaceous coals of Colorado are, according to Hills, 5 practically 

all of Laramie age, i. e., they belong to a horizon above the Pierre or 

Fox Hills. The Texas Cretaceous- coals are geologically older than 

the Colorado coals.

1 C. A. Ashburner, Mineral Kesources U. S. 1885, p. 68. *

2 \V. M. Chandler, Mineral Resources U. S. 1886, p. 350.

3 W. H. von Streeruwitz; Fourth Ann. Kept, of Geol. Survey of Texas, Austin, Texas, July, 1893, p. 175.

*W. H. von Streeruwitz; loc. cit.

o Mineral Resources U. S. 1892, pp. 319-324.
VAOGHAN.] SAN CARLOS COAL FIELD. 87

CHARACTER OF SAN CARLOS COAL.

The San Carlos coal is lustrous black in color, compact, and has a 

dark-brown streak and a subcubical cleavage. The following analyses 

were made by Dr. Peter Fireman:

t 

Analysis of San Carlos coal from mine No. 4, lower seam.

Moisture ..........

Vol. hydrocarbon . .

F. C. I

Ratl°V.H. C.J 

Ash...............

Color of ash .........

Coke..............

Upper part of 

seam above 

binder.

1.09

39. 61 

35. 29

QQ

24.01

Brownish

. gray. . 

Coherent,

hard, lustrous.

.lust above " 

binder 

(coking) .

1.17

39.93 

35.39

.886

23. 51

Gray.

Coherent,

hard, lustrous.

Below binder 

(coking) .

1.19

39. 73 

40. 30

1.01

18.78

Grayish

brown. 

Coherent,

hard, lustrous.

In clay above 

lower seam.

1.68

60.37 

24.89

.41

13. 06

R e d cl i s h

brown. 

Coherent,

lustrous.

Analysis of San Carlos coal from mine No. 4, lower seam.

Fixed carbon .......... ...........

Katio lvatio v RCH _ - cj........ 1 ........... 

Ash..............................

Color of ash .......................

Coke .............................

Coal (shaft).

.97

40.95

43.77

1.06

14.31

Coke.

1.24

4.96

66. 93

26. 87

Coherent, hard,

lustrous.
88 RIO GRANDE COAL FIELDS OF TEXAS. [BULL. 164.

The following data were furnished by Mr. R. E. Russell, former 

general manager of the San Carlos Coal Company: l

Analysis of coal from Presidio County, Texas.

Moisture .--.....-...-.-.....---...-...............

Volatile matter ....................................

Fixed carbon ......................................

Ash ............................................

Sulphur ..........................................

No. l.

Per cent. 

1.

39.05

49.05

10.

Trace.

. No. 2.

Per cent. 

0.94

34.48

58.96

5.62

.64

This analysis was undoubtedly made from picked samples.

A test of the coal for steaming purposes was made on the Southern Pacific Kailroad. The coal tested had been subjected to exposure for five or six months on the 

various dumps, and was practically crop coal, yet the average mileage for a ton of 

coal was 52.21 on passenger trains of five or six coaches.

Tests of the coking qualities of the coal were made at Connellsville, Pennsylvania, 

with good results. Forty-eight hour coke, burned in the oven at the mine, quite 

recently gave the following results:

Analysis of coke from Presidio County, Texas, coal.

'

Ash ..........................................................

Per cent.

93.7

6.2

REPORT OX IG1STEOTJS ROCKS FROM THE VICINITY OF 

SAN CARLOS AND CIIISPA, TEXAS.

By E. C. E. LORD.

The material submitted to me by Mr. T. Wayland Vaughan for 

petrographic examination was taken from a series of late Cretaceous or 

early Tertiary lava flows, constituting a large part of the Vieja 

Mountains, Texas.

The geologic relationship and distribution of these igneous rocks 

is explained by Mr. Vaughan in the foregoing text.

. The only literature bearing directly upon the petrography of the 

region is a short report by A. Osann2 on a specimen of nephelinetephrite and a series of syenite-porphyries or quartzless porphyries 

from the Vieja Mountains. The description of the latter rock corresponds somewhat with that of the quartz-pantellerite given below, 

but no reference is made by the author to triclinic feldspar, segirineaugite, or porphyritic quartz.

1 Mineral resources U. S. 1893, p. 385.

2 A. Osann, Report on the rocks of Trans-Pccos Texas : Fourth Ann. Kept. Geol. Survey of Texas, 

1892, p. 34.
LORD.] IGNEOUS BOOKS FEOM SAN CABLOS FIELD. 89

The specimens submitted represent three distinct rock types, which 

may be classified as follows :

(1) Rhyolite breccia, composed chiefly 'of fragmental rhyolitic 

material.

(2) Quartz-pantellerite, containing quartz, anorthoclase, and monoclinic pyroxene, as principal mineral constituents.

(3) Basalt, having olivine, augite, and plagioclase as essential 

minerals.

RHYOLITE BRECCIA.

Under this heading are considered a series of yellowish, or purplishgrey, very fine-grained, vesicular breccias, and a series of brownishred more massive rhyolites (5,23), x containing little fragmental material. 

The specimens are considerably weathered. They adhere to the tongue, 

and have a strong clayey odor when breathed upon.

With the aid of the microscope considerable variation in the mineralogical composition of these pyroclastics is discernible. Angular particles of quartz, orthoclase, plagioclase, biotite, muscovite, hornblende, 

magnetite, and occasionally tkanite, augite, and zircon, together with 

fragments of rhyolite, sandstone, limestone, and basalt, are seen 

cemented together by rhyolite glass decomposing into argillaceous 

material. This groundmass, although greatly altered to quartz and 

chalcedony and impregnated with calcite, chlorite, and limonite, showed, 

with two exceptions (Nos. 12 and 13), 2 fluidal phenomena.

Microscopic cavities are very abundant in these rocks. They are in 

many cases elongated, approximately in the direction of flow, and are 

more or less completely filled with silica, either in the form of radiating quartz (17), chalcedony (5), or opal (18). This secondary silica 

is stained reddish or yellowish brown by infiltrated iron ore.

In one instance (No. 13) the siliceous cement of the rock was almost 

completely replaced by calcite.

On comparing the relative amount of fragmental material occurring 

in the different members of the series, it was found that Nos. 10, 12, 

13, 17, and 18 contain all the clastic constituents enumerated above, 

whereas Nos. 5 and 23, representing the more massive flows, were 

characterized by the scarcity of foreign material and by the abundance of corroded quartz, orthoclase, and biotite phenocrysts. These 

latter specimens are much decomposed, and owe their peculiar brownish-red color to the presence of limonite and iron oxide in the groundmass of the rock. The feldspar phenocrysts are, in many cases, found 

completely altered to an aggregate of cryptocrystalline quartz. In 

some instances the rock from flow No. 5 is much fractured, and near

1 The numbers used in referring to the rock specimens are the same as those used by Mr. Vaughan 

in describing the section 6 miles west of south of Chispa, p. 76.

2 These specimens were not vesicular, and may perhaps be more properly designated tuffs.
90 BIO GRANDE COAL FIELDS OF TEXAS. [BULL. 164.

the surface very vesicular. The fissures and amygdaloidal cavities 

are filled with quartz and chalcedony.

Nos. 10 and 12 differ from the other specimens described in the 

predominance of augite, plagioclase, magnetite, and fragments of 

basalt over the debris of more acid rocks.

QUARTZ-PANTELLERITE.

This rock type is characterized microscopically by the presence of 

large feldspar phenocrysts embedded in a dense, aphanitic ground-- 

mass. The prevailing color of the rock is grayish green, with a slight 

yellowish tint.

The altered specimens are either spotted brown or have a brownishred color similar to much-altered varieties of the fragmental rhyolites 

Nos. 5 and 23. On exposed surfaces the pantellerite weathers yellowish brown and the feldspars are completely decomposed and leached 

out. Under the microscope the porphyritic character of the lava is 

more pronounced by the identification, besides feldspar, of porphyritic quartz, augite, magnetite, and apatite. These minerals are strewn 

in a fine-grained, holocrystalline groundmass composed of eegirineaugite, brown hornblende, feldspar, quartz, and magnetite.

The feldspar phenocrysts are thick tabular, formed after M (010). 

The planes M (010), P (001), y(201), T(lTO), and 1 (110) were identified. 

The crystals are large, measuring about one-third cm. in thickness, 

one-half cm. in width, and two-thirds cm. in length, and cleave readily 

fl M and P.

On cleavage plates parallel to the latter face a small extinction angle 

of not over 3° was observed, whereas on the plates parallel to the 

brachypinacoid the angle from a to a was circa 10°. These triclinic 

feldspar crystals are apparently single individuals, but occasionally

show a wavy extinction, owing, presumably, to polysynthetic twinning. 

The specific gravity of the feldspar was determined with great care 

from selected material, by means of the Thoulet solution, and found to 

be 2.59, or that characteristic of anorthoclase.

These crystals contain inclusions of magnetite, augite, and apatite, 

and are frequently considerably altered, either to calcite or natrolite 

and kaolin.

The augite of intratelluric origin is of a light-green color, and 

slightly pleochroic: || £ pale olive green, || a and || ft yellowish green. 

It has an extinction angle of about 42°, and occurs in long prismatic 

form, with imperfect terminal faces. On basal sections the crystals 

are seen bounded by oo P (110), oo P-QO (010), and oo P 06 (100) in about 

equal development.

Considerable variation in the relative amount of augite was noticed 

in the different specimens of pantellerite. In the slides containing 

least quartz the pyroxene was found to be most abundant.
IGNEOUS BOOKS FEOM SAN OAELOS FIELD. 91

The quartz phenocrysts are small and much rounded by magmatic 

corrosion. They are quite free from inclusions and reasonably abundant in rocks poor in augite.

Magnetite and apatite occur in the form usually met vith in rhyolitic rocks. Phenocrysts of the former mineral are frequently covered 

with a coating of limonite, which discolors the surrounding rock for 

some distance and produces the brown spots referred to above.

In the groundmass of the pantellerite the presence of segirine-augite 

and hornblende is of special interest. The former mineral occurs in 

the form of minute, irregularly bounded crystals of a rude prismatic 

habit.

The microlites are of a grass-green color, and in polarized light show 

characteristic pleochroisrn: | a grass green, || ft sap green, and || £ pale 

yellowish green. The absorption is a>ft>£. On prismatic sections 

the axis of greatest elasticity (a) was found to lie nearest c, the 

extinction angle not exceeding 25°. Twins after o> P~c» (100) are occasionally observed.

The hornblende is not so abundant in the groundmass of this rock 

type as is the pyroxene. It occurs in thin sections, in irregular 

wedge-shaped patches, showing distinct prismatic cleavage, and is 

often intimately associated, although never intergrown, with the 

cegirine-augite. It is dark brown and exceedingly pleochroic: || £ dark 

brown, | fr purplish brown, and | a brownish yellow. Absorption is 

strong: jc>ft>a.

The extinction is considerable, £ forming on sections in the prism 

zone a maximum angle of 15° with the trace of the prismatic cleavage.

From the optical properties mentioned it is probable that this 

amphibole is closely related to barkevicite. 1

Both the brown hornblende and the segirine-augite are in many cases 

altered to chlorite and limonite. The fibrous mineral is regularly distributed through the rock; it occasionally occurs associated with 

serpentine .as the probable alteration product of preexisting olivine 

crystals.

Feldspar and quartz of the effusive period are of microgranitic 

development and constitute the greater part of the pantellerite groundmass. The former mineral is of prismatic form, and occasionally quite 

idiomorphic. The microlites are elongated parallel &, but in no instance 

could twinning be identified. As prismatic sections they show extinction angles not exceeding 10°, and may properly be regarded as a 

second generation of anorthoclase. The interstices of the rock are 

filled with allotriomorphous quartz.

The following analysis of the quartz-pantellerite from Presidio 

County, Texas, was made by Mr. Geo. Steiger, of the United States 

Geological Survey. Before making the analysis the calcium carbo-

!H. Rosenbusch: Mikros. Physiographic, Vol. I, 3d edition, Stuttgart, 1892, p. 561.
92 EIO GKANDE COAL FIELDS OF TEXAS. [BULL. 164.

11 ate present was removed by treating the rock powder on the water 

bath for ten minutes with diluted hydrochloric acid (1-10). The result 

of the analysis is found under Table I.

For comparison, the average of five analyses of pantellerite from 

Pantelleria 1 is placed under Table II, and under Table III is placed 

the average of paisanite from Mosquez Canyon. 2

I. Analysis of quarlz-pantellerite from Presidio County, Texas.

Constituent.

Si0.2 .......................................... 68.71.

Ti02 .......................................... .21

A12 03 -....:................................... 13.45

Fe2 03 ----------------------T-................. s 5.31

FeO.......................................... .75

MnO......................................... .14

CaO....... ................................... .96

BaO.......................................... None.

SrO .......................................... None.

MgO ...............................i......... .19

K2 0.......................................... 5.51

Na2 0......................................... 4. 63

Li2 0.......................................... None.

Water 100° ................................. .13

Water 100°+ ................................. .36

S03 .......................................... .05

PA------------------------------------------ -04

CO;, .......................................... None.

Total....................................... 100. 44

Per cent.

!H. Foerstner: Zeitsch. fur Krystallog., Vol. VIII, 1884, p. 125.

2 A. Osann, Beitrage zur Geologie und Petrographie der Apache (Davis) Mountains, Westtexas: Min. 

und Petrogr. Mitth., Vol. XV, 1895, p. 439.
LORD.] IGNEOUS BOOKS FKOM SAN CAELOS FIELD.

II. Average of five analyses of panlellerite from Pantelleria.

93

Constituent. Per cent.

SiO,.......................................... 68.78

Al A-....-....-....--..--..-------.-----.--.- 8. 59

FeA- -...-...............-.--...----.-.---... 5.12

FeO........................................... 3. 78

CaO.......................................... 1.44.

MgO ......................................... .53

K£>.......................................... 3.50

Na,0 ......................................... 7.16

CnO.......................................... .15

HA..................................'...... .36

III. Analysis of paisanite from Mosquez Canyon, Texas.

Constituent. Per cent.

SiO, .......................................^.-. 73. 35

A1A- - -.-.........--------.--.----..-------..- 14. 38

FeA ........................................ 1.96

FeO.......................................... .34

MgO ......................................... .09

CaO.......................................... .26

Na.,0......................................... 4.33

K,0.......................................... 5.66

Total................................... 100.37

It will be seen that while the silica, iron oxide, and some, of the 

alkalies are essentially the same in the first two tables, the amount of 

FeO and Na2O is smaller, and of A12O3 and K2 0 is larger, in Analysis I 

than in Analysis II.

This discrepancy in the chemical constitution of the two rock types 

is caused by the chemical dissimilarity of their aniphibole constituents, 

all other silicates being alike in both rocks. The barkevicitic hornblende (rich in A12O3 and comparatively poor in FeO and Na2O) of 

the pantellerite from Presidio County is represented in the lava 

from Pantelleria by cossyrite, poor in A12O3 and very rich in FeO and 

Na.0. 1

The relatively large amount of potash in Analysis I would indicate 

also a predominance of the potash feldspar molecule in the composition 

of the anorthoclase in the Texas pantellerite. v

Comparing the analysis of this lava (Table I) with that of the paisa1 F. Foerstner, Ueber Cossyrite: Zeitsch. fiir Krystallog., Vol. V, 1881, p. 354.
94 EIO GRANDE COAL FIELDS OF TEXAS. [BULL. 164.

nite (Table' III) it will be noticed that the latter rock differs essentially, 

containing a larger amount of silica and a smaller amount of iron. This 

chemical variation is manifested mineralogically by a greater development of free silica and by a total absence of ferromagnesian constit- 

. uents in the groundmass of the rock. 1

The geological occurrence of the paisanite2 in" the characteristic dike 

form is in marked contrast to the typical effusive character of the 

pantellerite.

The distribution of pantellerite outside of Texas is limited to the 

island of Pantelleria, although similar lava types are found on some 

of the volcanic islands off the coast of Africa, as well as on the 

mainland itself.

Pantelleria is situated about 70 miles southwest of Sicily, nearly 

midway between that island and Africa. It was visited in 1829 by 

Gemmellaro, who described from there a peculiar, greenish-gray 

rock type as '' lave trachitichi moderne. "3

In 1881 Foerstner named this lava pantellerite, and characterized it 

as a young, effusive rock, rich in iron, and containing a hornblendic 

mineral, called by him cossyrite^ In a later paper 5 he says that the 

rock shows sometimes a trachytic, often a vitreous obsidian, habit, 

and that it covers an area of 40 to 60 square kilometers, or the major 

part of the island. Forty-five volcanic centers and fifty flows surround an andesite core. Besides the latter rock, the pantellerite was 

associated with phonolite, feldspar, basalt, .and rhyolite.

It has already been shown that in the Vieja Mountains the two latter rock types accompany the pantellerite. Phonolite and andesite 

from the Davis Mountains, 30 to 70 miles east of the Vieja Range, have 

been described by Osann. 6 This similarity in the mineral composition, 

as well as the geological associations of these younger rocks with the 

lavas from Pantelleria, renders the disco very in Texas of a similar circumscribed area of eruption a matter of great interest.

The following are some of the more important occurrences of 

younger-rock types resembling pantellerite in their mineral composition :

(1) Acmite-trachyte from the islands of San Miguel and Fayal, of 

the Azores, and from the island of Terceira; 7 also from the neighborhood of Naiwaseha Lake and from the Kaiwangaine Valley, northeast 

of Kilimandscharo Massif, East Africa. 8

1 Osann, op. cit., p. 438.

2 Ibid., pp. 404, 405.

3 C. Gcmmellaro, Sopra 1' isola vulcanica di Pantelleria: Atti dell' Accad. Gioenia, Vol. V, 1829.

4 H. Foerstner, Nota preliminare sulla geologia dell' isola di Pantelleria: Jloma, Tipogr. Barbea, 

1881, p. 15.

6 Ueber Cossyrite: Zeitsch. fiir Krystallog., Vol. V, 1881, pp."348-349.

6 Osann, op. cit., p. 126.

7 0. Miigge, Petrog. Untersuchung. an Gesteinen von den Azoren: Neues Jahrb. fiir Min., Vol. II, 

1883, pp. 212-218.

»O. Miigge, Ueber einige Gesteine des Massai-Landes: Neues Jahrb. fiir Min., Vol. IV, 1886, p. 591.
LOBD.] IGNEOUS BOOKS FEOM SAN CAKLOS FIELD. 95

(2) Dacitic rhyolite from Iceland, in Oexnadalr. 1

(3) Trachyte from Sierra Madre, on southwest flank, near the town 

of Tulancingo, Mexico. 2

(5) Volcanite from the island of Volcano, of the Liparian group. 3

BASALT.

This rock varies in color from grayish black to dark brown, and 

on macroscopical examination presents a decided porphyritic character, owing to the development of large olivine and plagioclase phenocrysts.

It appears in the form of an intruded sheet between rhyolite breccias Nos. 10 and 12. Near its upper surface the rock is a typical 

amygdaloid.

With the aid of the microscope the basalt was found to pass from a 

dense holocrystalline porplryritic rock to a vesicular, hypocrystalline 

porphyritic variety.

The first-mentioned type (11) is composed of large, tabular-formed 

labradorites, irregularly bounded olivine and magnetite crystals of 

intratelluric origin, and light-brown augite, plagioclase, and magnetite 

of the effusive period. The augite is rarely of idiomorphic form, and 

contains abundant plagioclase inclusions. In many cases this pyroxene was the last mineral constituent of the grouridmass to crystallize, 

arid in taking the part of a niesostasis produced a characteristic ophitic 

structure common to many types of diabase. In some cases the olivine 

is replaced by the questionable mineral iddingsite.

The vitreous and porous variety of basalt (11') differs from the holociystalline rock in the development of a dark-brown granulated glass 

base in the groundmass. This rock type is, however, very much decomposed, olivine and augite being often completely altered to limonite, 

chlorite, and serpentine. .These secondary minerals, together with 

either calcite, natrolite, or opal, are concentrated in the amygdaloidal 

cavities of the rock.

!P. Schirlitz, Islandische Gcsteine: Min. u. Petrographische Mitth., Vol. IV, 1882, p. 423.

2 C. A. Tenne, Ueber Gesteine des Cerro de las Vajos (Messerberg) in Mexico; Zeitschr. Deutsch. 

geol. Gesell., Vol. XXXII, 1885, pp. 612-613.

3 W. H. Hobbs, Ucber den Volcanit, ein Aiiort-hoklas-Augit-Gestein von der chemischcn Zusammensetzung derDacite: Zeitschr. Deutsch. geol. Gesell., 3893, p. 578.

INDEX.

Page. 

Acmite-trachyte, occurrence of............. 94

Adams, W. H., work of ..................... C7

Analyses, coal ..........;.... .60,61,64,65,66,87,88

coke.................................... 88

lignites................................. 66

pantellerite.............................. 93

quartz-pantellerite..................... 92

Anacacho formation, section of............ 31-32

stratagraphic position of ............... 31

variations in character of.............. 34

Anacacho Mountains, Kinney County, figure showing section of.............. 32

section of:.............................. 31-32

Ashburner, C. A., cited on coal at El Paso . 86 

Asphalt Falls, section at.................... 34

Atascosa County, analysis of lignite from.. 66 

Athens, analysis of lignite from............ 66

Austin, thickness and character of Taylor

marls near.......................... 34

Austin chalk, fossils found in .............. 19-20

section of, Anacacho Mountains........ 32

occurrence and character of........... 19-20

Balcones tscarprnent, altitude of........... 14

Basalt, description of....................... 95

Bassett, C. C.,aid by..................... 78,83,84

Brackett, fossils found 20 miles west of..... 17

thickness of Eagle Ford formation at... 19

thickness of Buda limestone near...... 18

Bracks Canyon, description of.............. 82

plate showing view of............... 1.. 82

Bray, W. L., work of ........................ 15

work with.............................. 11

Bregg, G., information furnished by........ 57

section furnished by.................... 23

Budalirnestone, occurrence and character of 18 

Burr's ranch, fossils found near ............ 25-26

Calvert bluff, analysis of lignite from....... 66

Campbell, J. W., section furnished by....... 50

Cannel Coal Company, analysis of coal from

mine of............................. 65

record of prospect drill by.............. 41-42

section at mine of ...................... 44

Caprina limestone. See Edwards limestone. 

Carbon, record of prospect drill near....... 41-42

Carrizo sandstone, occurrence of............ 54

Carrizo Springs, plate showing artesian well

near................................ 52

reconnaissance between Santo Tomas,

Uvalde, and ........................ 50-51

reconnaissance from Eagle Pass to.. 30-31,46^7

reconnaissance from San Lorenzo Creek

to................................... 47

relation of Cretaceous to Eocene between Eagle Pass and .............. 35-36

section of well near .................... 50

Bull. 164 7

Cavender, G. G., information furnished by.. 50 

Chacon Creek, character of surface near ... 28 

Chandler, W. M., cited on coal at Eagle

Springs............................. 86

Chapman, R. H., aid by..................... 83

Chispa, fossils found near.................. 84

location of.............................. 73

plate showing view of Vieja Mountains 

from ............................... 76

report on igneous rocks from vicinity of

San Carlos and ..................... 88-95

sections near ........................... 76,84

topography near........................ 74

Cbupadero ranch, sandstone at............ 37

Cline, reconnaissance from Eagle Pass to.. 28-30 

Coal, age of Cretaceous'of Colorado ........ 86

analyses of .............. 60,61,64,65, G6,87.88

character of............................ 60-61

importance of, in Texas................ 11

occurrence of........................... 62,86

thickness of............................ 57

Coal fields in New Mexico and Texas...... 11-12

Coal series, fossils found in................. 25-26

occurrence, character, and thickness

Of................................ 22-26,28

Coke, analyses of........................... 88

Comanche series, consideration of ......... 16-18

Comstock, T. B., work of.................... 71

Cope, E. D., work of........................ 67

Cow Creek, exposure of Austin chalk on... 19 

fossils found on......................... 19-20

Cretaceous, course of boundary between 

Eocene and.........................

plate showing contact of Eocene and.. 

relation of Eocene to ...................

Cretaceous rocks of the Eagle Pass coal

field ................................ l'5-37

Davis, D. D., acknowledgments to........... 44

aid by ............................ 14,40,44,45'

reference to ............................ 63

statement by ........................... 42

Del Rio, Del llio clays near................. 17

Edwards limestone at.................. 16

fossils found near ...................... 17

section near............................ 17

Del Rio clays, fossils found in .............. 17

occurrence and character of........... 17

Dolch,L.,map furnished by................ 56

sections furnished by................... 57

Dolch, L. F., & Co., prospect shaft of........ 24

Bumble, E. T., cited on age of Escondido

beds................................ 27

cited on analysis of coal................ 65

cited on designation of Eagle Ford formation................................ , 19

97
98 INDEX.

Page.

38

75

Bumble, E. T., cited on Eocene fossils .....

cited on fault near San Carlos..........

cited on quality of coal found near 

Uvalde .............................

cited on section at Webb bluff..........

cited on thickness of Austin chalk 

beds................................

cited on thickness of Eagle Ford formation ...............................

cited on time of volcanic outbursts ....

cited on value of lignite................

 formations described by...'.............

quoted on Upson clays .................

quoted on San Miguel beds ............ 21-22

reference to ................... 19,21,22,35,82

section given by...................... 1. 78

works of.......................... 70,71-72,74

Eagle Ford formation, occurrence and character of............................. 18-19

Eagle Pass, character and constitution of

coal from..........-..............'... 60

fossils found near................. 22,20,27,30

map showing coal mines and prospects

near................................ 56

plate showing bluff of Rio Grande at... 54 

plate showing view of Rio Grande opposite. .............................. 26

rainfall and temperature at............ 15

reconnaissance between Carrizo Springs

and........................... 30-31,46-47

reconnaissance from Cline to........... 28-30

relation of Cretaceous to Eocene between Carrizo Springs and ......... 35-36

section of artesian well near ........... 25

sections near ............... 22,23,26,30,57-58

thickness of coal bed near ............. 57

Eagle Pass coal fields, consideration of..... 13-61

climatic conditions of................... 15

descriptive geology of........:......... 15-55

extent of ............................... 55

limits of................................ 13

map of.................................. 13

mines in................................ 60

physical features of .................... 13-15

vegetation in........................... 14-15

Eagle Pass formation, fossils found in. 22,25-20,27 

section of............................... 34

thickness, occurrence, and character of. 21-28 

variations in thickness of............;. 35

Edwards limestone, exposures of........... 16

fossils found in ......................... 84

Elm Creek, figure showing section of hill on. 23 

Engelmann ranch, section near ............ 51

Eocene, course of boundary between Cretaceous and......................... 53

conclusions regarding.................. 53-54

plate showing contact of Cretaceous

and................................. 50

plates showing exposures of............ 50,52

relation of Cretaceous to............... 35

r6sum6 of section of.................... 45

thickness in Uvalde quadrangle........ 53

Eoce.ne coal fields, extent of................ 61-02

Eocene rocks, consideration of.............. 37-54

Escondido beds, description of.............. 26-28

 fossils found in......................... 26-27

Fireman, P., analyses by ............. 60,64,65,87

Page. 

Foerstner, H., cited on pantellerite......... 92,94

Fort Clark, rainfall and temperature at.... 15

Fort luge, rainfall and temperature at..... 15

Fort Worth limestone, fossils found in...... 16-17

occurrence and character of............ 10

Frazier, S. D., information furnished by.... 62

reference to............................. 59

Frio River, fossils found on................. 52

plates showing Eocene and' Cretaceous

rocks on ............... ............. 50J52

relation of Cretaceous to Eocene along. 36 

sections of Eocene on................... 51-53

Fuente mines, Mex., section at ............ 24

thickness of coal seam in................ 57

Gemmellaro, C., cited on pantellerite...... 94

Gettysburg Peak, plate showing view of.... 80

sections of........................... 81,84

Gobbett survey, section of well on......... 51

Greely, A. W., cited on climatic conditions

of Texas............................ 15

Guajolote ranch, sections at and near...... 39,40

Habey ranch, sections near................ 48

Harris G. D., cited on Eocene fossils........ 38

cited on relation of Cretaceous to Eocene in Rio Grande section......... 35

quoted on fossils found near Eagle Pass. 39 

reference to ............................ 44

work- of................................. 71,72

23,57 

59 

50

14

Hartz mine, thickness of coal at............

Hector, 0. P., information furnished by....

Herman, G. C., information furnished by.. 

Hill, R. T., cited on "Balcones escarpment" ..............................

cited on coal in Chisos Mountains......

cited on constitution of coal in Santa 

Rosa region.........................

cited on Eagle Ford formation.........

cited on Santa Rosa coal field ..........

letter of transmittal by.................

reference to ......................... 11,

work of........................... OS,69-

Hill, R. T., and Vaughan, T. W., cited on 

Anacacho formation................

cited on geology of Edwards Plateau and 

Rio Grande Plain...................

cited on Rio Grande Plain..............

cited on Taylor marls...................

work of.................................

Hills, R. C.. cited on coal from Colorado ....

Hitchcock, C. H., work of...................

Hobbs, W, H., cited on occurrence of volcanite ..............................

Igneous rocks, report on ....................

India ranch, fossils found near .............

Johnson, S. A., acknowledgments to........

information furnished by...............

Johnstone, elevation at.....................

Knowlton, F. H., fossils determined by.. 23,

notes by................................

reference to.............................

Laredo, analysis of coal from...............

rainfall and temperature at.............

section along Rio Grande from Webb 

bluff to..............................

Las Moros Creek. See Tulio Creek.

reference to.............................

Leon County, analysis of lignite from ......

61

18

56

9

62,73 

 70,71

31

54

13,14

34

72

11,86

07

95

88-95 

38 

73 

75 

13

45,47 

40 

36 

60 

15

46

20,22

66
INDEX. 99

Page. 

Lewis ranch, section of bluff near........... 52

Lignites, analyses of........................ 06

Loma Vista, fossils found near.............. 50

Lord, E. C. E., report on igneous rocks from

vicinity of San Carlos and Chispa.. 88-95

work of................................. 73

. Loughridge, R. H., work of................. 67

Lucas, F. A., fossils examined by.......'-.... 81

Maloney, J. J., acknowledgments to........ 73

Marshall, G. N., acknowledgments to....... 73

information furnished by .............. 86

Maverick County Coal Company, section in

mine of............................. 23

thickness of coal seam mined by ....... .57

McDaniel ranch, sections near .......... 48,49,62

McGee, W J, definition by .................. 16

work of.............................. 67,70-71

Mexican ranch, section of hill near......... 52

Mosquez Canyon, analysis of paisanite from 93

M(igge,0., cited on occurrence of acmite-

'trachyte ............................ 94

Mula Creek, character of surface and vegetation near ......................... 28

Myrick apiary, section of bluff at........... 52

Neocene rocks, extent of.................... 55

Nueces River, occurrence of coal near...... 62

relation of Cretaceous to Eocene along.. 36 

sections of Eocene on............. 34,47-50,62

thickness of Eagle Pass formation on .. 35 

New Mexico, coal field in Texas and....... 11-12

Olmos Creek, section on.................... 58

Osann, A., cited on igneous rocks .......... 88

cited on paisanite ..:................... 92,94

work of................................. 74

Ott, M. C., information furnished by....... 62

Owen, J., analysis of specimens collected by. 65 

cited on Carrizo sands.................. 37

cited on coal near Uvalde .............. 61

cited on thickness of coal bed near

Eagle Pass.......................... 57

fossils collected by...................... 27

work of................................. 68-69

Paisanite from Mosquez Canyon, analysis of 93 

Palafox, figure showing section of bluffs

and terraces at...................... 55

section of butte near ................... 40

Paloma siding, fossils found near........... 25-26

Pantelleria, analysis of pantellerite from .. 93 

Pantellerite from Pautelleria, analysis of.. 93 

Penrose, R. A. F.,analyses by .............. 61,66

cited on fossils from. Webb bluff........ 45

cited on Santo Tomas coal.............. 66

cited on section at Webb bluff ......... 39

quoted on section along Rio Grande 39 

from Webb bluff to Laredo .'........ 45

reference to ............................. 35

work of................................. 69

Pilot ranch, record of prospect drill at..... 42-44

Pleistocene terraces, occurrence of......... 55

Presidio County, analyses of coal and coke

from................................ 88

analysis of quartz-pantellerite from.... 92

Quartz-pantellerite from Presidio County,

analysis of.......................... 92

description of.......................... 90-95

geographic distribution of.............. S3

Rhyolite breccia, description of............ 89-90

Page. 

Rhyolite, dacitic, occurrence of............ 95

Rio Escondido, section on.................. 24

Rio Grande, conclusion regarding coal fields

of the .............................. 66-67

Eocene rocks near...................... 37^6

generalized diagram of terraces on..... 55

plate showing bluff at Eagle Pass ...... 54

plate showing view of.................. 26

relation of Cretaceous to Eocene along.. 35 

section from Webb bluff to Laredo

along............................... 46

section on .............................. 20

thickness of Eagle Pass formation on.. 35 

Rio Grande coal fields, map showing general position of..................... 14

Rio Grande Coal and Irrigation Company,

analysis of coal from mine of ...... 64

section at mine of...................... 44

Rio Grande Plains, topography of.......... 13-15

vegetation on .......................... 15

Riper, J. E. van, acknowledgments to ..... 73

Rock , analysis by......................... 61

Rockdale, analysis of lignite from ......... 66

Roessler, F. E., cited on section near Eagle

Pass.......:........................ 25

Roy, D. J., acknowledgments to ........... 44

Rusk County, analysis of lignite from...... 66

Russell, R. E., analyses furnished by........ 88

Sabinal, thickness of Anacacho formation

near ................................ 33

Sabinal River, exposures on ................ 34

Salado Creek, character of surface near .... 29

fossils found on and near .............. 29

section at ford on north side of.'........ 28

San Ambrosia Creek, exposures near ....... 37

section near............................ 38

San Carlos, altitude of...................... 75

character of coal from.................. 87

fossils from Vieja Mountains near.. 78-79,80 

location of.............................. 73

map showing topographic features -in

vicinity of.......................... 74

plates showing views from............. 80,82

report on igneous rocks from vicinity

of Chispa and....................... 88-95

sections near ............... 77-78,79-80,81,84

topography near........................ .75

San Carlos Coal Company, fossils from fault

near shaft of........................ 81

sections in coal seam aud shaft of...... 79-80

San Carlos coal field consideration of...... 73-88

San Carlos formation, strata below ......... 84-85

fossils found below..................... 84

section of beds below................... 84

San Carlos section, re'sume' of............... 81

San Felipe Creek, Fort Worth limestone on. 16 

San Felipe Springs, fossils found near ...... 16-17

San Lorenzo Creek reconnaissance from

Carrizo Springs to .................. 47

San Miguel beds, fossils found in........... 22

occurrence and character of......... 21-22,28

San Pedro seam, section of................. 63

Santa Rosa region, analysis of coal from ... 61 

Santo Toinas, dip at ........................ 45

elevation at............................ 13

figure showing sandstone and clays

above coal horizon at .............. 54
100 INDEX.

Page. 

Santo Tomas, reconnaissance between

Uvalde, Carrizo Springs and ....... 50-51

record of prospect drill near............ 41-4?

Santo Tomas coal field, character of coal in 64-66 

extentof...,..............'............. 62-63

mines in................................ 64

Santo Tomas mine, section at.............. 44

Santo Tomas seam, section of............... 63

Schirlitz,P., cited on occurrence of dacitic

rhyolite............................. 95

Schott, A., work of ......................... 67

Seibert, C., acknowledgments to ........... 73

Shelby County, analysis of lignite from .... 66

Shoal Creek limestone. See Buda limestone. 

Stanton,T.W., aid by ...................... 11

fossils collected by ..................... 45

fossils determined by. 19-20,22,25,26,27,29,30 

notes on age of fossils by ............... 82

quoted on fossils from Salado Creek.... 29

statement by ........................... 27

work of................................. 73

Steeruwitz, W. H. von, cited on coal in

Trans-Pecos Texas. . r ............... 86

work of................................. 74

Steiger, G., analysis by ..................... 92

Stevenson,J.J.,cited onCerillos coalfield.. 11 

Taff,J.A.,workof .................!........ 71

Taylor marls, character and thickness of... 34 

Tenne, C. A., cited on occurrence of trachyte ............................... 95

Tertiary rocks, consideration of ..'.......... 37-55

Texas, coal fields in New Mexico and ...... 11-12

Thompson, P. W.,information furnished by 58 

Thompson, E., statement by ................ 60

Page. 

Trachyte, occurrence of.................... 95

Tulio Creek, fossil found at................. 20

Turkey Creek, compilations of sections

along............................... 32-33

Upson, section near......................... 20

Upson clays, occurrence and character of.. 20-21 

variations in character of.............. 34

Uvalde, reconnaissance between Carrizo

Springs, Santo Tomas, and.......... 50-51

Valverde flags. See Eagle Ford formation.

Van Horn Creek, course of ................. 74

Vaughan,T. W., reference to................ . 88

work of................................. 72

Vaughan, T. W., and Hill, R. T., cited on

Anacacho formation................ 31

cited on geology of Edwards Plateau and 

Rio Grande Plain...................

cited on Rio Grande Plain.............. 13,14

cited on Taylor marls .................. 34

work of................................. 72

Vieja Mountains, coal in ................... 86

fossils from............................. 78-79

mountains composing.................. 74

plates showing views of................ 76,78

sections of ........................ 76-78,79-80

structure of............................. 75

Volcanic outbursts, time of................. 83

Webb bluff, section along Rio Grande from

Laredo to............................ 46

section of............................... 39

Well, artesian, at Eagle Pass, section of..... 25

White, C. A., formation named by .......... 21

fossils collected by...................... 45

reference to.......................... 35,39,82

work of................................. 68,70

o