The geography of Texas

Prefatory Note

In the preparation of this text, which necessarily covers a somewhat varied field, I have, in general, been guided by the following works :

ON PHYSICAL GEOGRAPHY AND GEOLOGY

The Reports of the Geological Survey of Texas, under the direction of E. T. Dumble, state geologist. Austin, 1890-1893.

'' Notes on the Physical Geography of Texas," by Ralph S. Tarr. Proceedings of the Academy of Natural Sciences. Philadelphia, August 29, 1893.

" The Physical Geography of the Texas Region," by Robert T. Hill. Folio 3 of the Topographic Atlas of the United States. Washington, United States Geological Survey, 1900.

" Physical Geography, Geology, and Resources of Texas," by E. T. Dumble. Chapter IV, Volume 2, of A Comprehensive History of Texas, edited by Dudley G. Wooten. Dallas, William G. ScarfE, 1898.

" The Geology of the Edwards Plateau and the Rio Grande Plain adjacent to Austin and San Antonio, Texas," by Robert T. Hill and T. Wayland Vaughan. Eighteenth Annual Report of the United States Geological Survey, Part II, pp. 193-321. Washington, 1898.

" Geography and Geology of the Black and Grand Prairies, Texas," by Robert T. Hill. Twenty-First A nn ual Report of the United States Geological Survey, Part VII. Washington, 1901.

"A Gazetteer of Texas" (second edition), by Henry Gannett. Bidletin of the United States Geological Survey, No. 224 (Series F, Geography, 36). Washington, 1904.

V vi PREFATORY NOTE

ON WATER POWER AND IRRIGATION

"The Water Power of Texas," by Thomas U. Taylor, C.E., M.C.E. Transactions of the Texas Acade7uy of Science, Yolume IV, Part II, No. I. Austin, 1902.

"Irrigation Systems in Texas," by William Ferguson Hutson. Water- Supply and Irrigation Papers of the United States Geological Survey, No. 1^5. Washington, 1898.

"Rapid Progress in Irrigation," article in the Texas Almanac and State Industrial Guide for 1904. Published by the Galveston-Dallas News.

" Rice Irrigation in Texas," by Thomas U. Taylor. Bulletin of The University of Texas, No. 16. Austin, 1902.

" Rice Growing on the Coastal Prairies," article in the Texas Almanac and State Industrial Guide for 1904. Published by the Galveston-Dallas News.

ON CLIMATE

" The Climatic Conditions of Texas, especially with Reference to Temperature and Rainfall." Report of the Chief Signal Officer [A. W. Greely] of the Army. Fifty-Second Congress, First Session, Executive Document No. 5. Washington, 1892.

"The Climate of Texas," by Isaac Monroe Cline, M.A., M.D. United States Department of Agriculture, Weather Bureau, Texas Weather Service, Special Bulletin No. 4. Galveston, 1894.

ON VEGETATION

" The Ecological Relations of the Vegetation of Western Texas," by Dr. William L. Bray. Contributions from the Hull Botanical Laboratory, XXX. The Botanical Gazette, Chicago, Volume 32, August, September, and October, 1901.

" Texas Forests and the Problems of Forest INIanagement for the Long-Leaf Pine Lands," by Dr. William L. Bray. The Forester, Volume 7, pp. 131-138. Washington, June 7, 1901.

" The Timber Pines of the Southern United States," by Charles Mohr, Ph.D. Bulletin No. 13, United States Department of Agriculture, Division of Forestry. Washington, 1896.

PREFATORY NOTE vii

"Forest Resources of Texas," by William L. Bray. Bulletin No. 47, United States Department of Agriculture, Division of Forestry. Washington, 1904.

" The Timber of the Edwards Plateau of Texas," by Williani L. Bray. Bulletin No. 49, United States Department of Agriculture, Division of Forestry. Washington, 1904.

ON FAUNA

"American Animals," by Witmer Stone and William Everitt Cram. New York: Doubleday, Page & Co., 1902.

"Handbook of Birds of the Western United States," by Florence Merriam Bailey. Boston and New York : Houghton, Mifflin & Co.,

" Key to North American Birds," by Elliott Coues. Boston : Dana

" The Crocodilians, Lizards, and Snakes of North America," by Edward Drinker Cope. Report of the United States National Museum for 1898, pp. 153-1270. Washington, 1900.

"The Poisonous Snakes of North America," by Leonhard Stejneger. Report of the United States National Museum for the Year ending June 30, 1893, Part II, pp. 337-487. Washington, 1895.

" The Poisonous Snakes of Texas, with Notes on their Habits," by J. D. Mitchell. Transactions of the Texas Academy of Science, Volume V, pp. 19-48. Austin, 1903.

ON MINERAL RESOURCES

The Reports of the Geological Survey of Texas, under the direction of E. T. Dumble, state geologist. Austin, 1890-1893.

Bulletins 1-5, inclusive, of The University of Texas Mineral Survey, William B. Phillips, director. Austin, 1901-1902.

The Mineral Industry, edited by Richard P. Rothwell. New York: The Scientific Publishing Company, 1893-1900.

viii PREFATORY NOTE

ON HISTORY

" Historical Sketch of Texas," by George Pierce Garrison, Ph.D Chapter II of The Government of the People of the State of Texas. Phihidelphia : Eldredge and Brother, 1900.

Texas a Contest of Civilizations, by George P. Garrison. Boston and New York : Houghton, Mifflin & Co., 1903.

ON GOVERNMENT

The Constitution of the State of Texas.

The Government of the People of the State of Texas, by George Pierce Garrison, Ph.D. Philadelphia: Eldredge and. Brother, 1902.

ON EDUCATIONAL INSTITUTIONS

Official Reports.

ON RAILROADS

Reports of the Railroad Commission of the State of Texas.

" The Railroads of Texas, with Glimpses of the Country through which they pass." The Texas Almanac for 1868, pp. 118-116. Galveston, 1868.

"The Development of the Present Texas Railway System," by R. A. Thompson, Assoc. M. Am. Soc. C. E., chief engineer, Railroad Commission of Texas. Transactions of the Texas Academy of Science, Volume IV, Part I, pp. 57-80. Austin, 1901.

ON POPULATION, AGRICULTURE, AND MANUFACTURES

Reports of the Twelfth Census.

I desire to record here my indebtedness to my colleague, Dr. George P. Garrison, and to the Hon. R. L. Batts, of the Austin bar, for valuable suggestions rehxting to history, government, and education ; also my indebtedness to

PREFATORY NOTE ix

Dr. H. Y. Benedict, for substantial aid in selecting representatives of the bird fauna, and to Mr. R. A. Thompson, chief engineer, and Mr. H. G. Askew, auditor, of the Railroad Commission of Texas, for assistance in the preparation of the railroad statistics. I am furthermore indebted to Dr. William B. Phillips, late director of The University of Texas Mineral Survey ; to Dr. William L. Bray, head of the School of Botany ; to Dr. A. M. Spurgin ; and to Mr. J. M. Kuehne for the use of many excellent photographs, reproductions of which appear among the illustrations. My thanks are also due to my assistant, Mr. Alexander Deussen, for suggestions and help such as can only be given by one closely associated with the writer in his work ; to Mrs. Grace Murray Stephenson for the final reading of the manuscript; and to Dr. H. E. Bolton for expert advice covering numerous difficult points. Many of the diagrams, tracings, and maps used in the text have been skillfully drawn by Mr. John W. Pritchett, a student of the Engineering Department of the University.

FREDERIC W. SIMONDS

ADDITIONAL NOTE

In the preparation of this revised edition use has been made of the following publications : The bulletins of the Thirteenth Census upon Population, Agriculture, Cotton, and iNlanufactures ; various issues of the Crop Meporter, published by authority of the Secretary of Agriculture ; the Tie enty -first Ammal Report of the Railroad Commission of the /State of Texas for the Year 1913; the Ammal Report of the Treasurer of the State of Texas to the G-ovemor for

X PREFATORY NOTE

the Fiscal Year ending August 31^ 1912 ; the Eighteenth Biennial Report of the State Department of Education for the Years ending August 31^ 1011 and August 31, 1912 ; the Texas Almanac and State Industrial Guide for the Years 1910, 1911, and 1912 ; the American Ba^ik Reporter, Vol. LXXXVI, June, 1918 ; the Official Luiustrial and Freight Shippers^ Directory of the Missouri, Kansas and Texas Railway System for 1912-1913 ; and many local articles descriptive of the various cities and towns of the state. The author again acknowledges his indebtedness to many persons who have kindly assisted him in securing much unrecorded information.

FREDERIC W. SIMONDS

Contents

CHAPTER I. — The State — Introduction — Location— ^^^es Boundaries — Area — Political Divisions — Cities and Towns ^-^

CHAPTER II. — Geology — The Relation of Geology to Physical Geography — Kinds of Rocks— Sedimentary Rocks — Igneous Rocks — Altered or Metamorphic Rocks — The Rocks of Texas — The Geological Map

— Recent and Neocene Systems — Eocene System — Cretaceous System — Jura-Trias System — Permian

Chapter I The State

1. Introduction. Geography is preeminently the science which treats of the earth and its phenomena in their relations to mankind. From this point of view an attempt will be made in the following pages to present those features which render Texas especially attractive as a dwelling place for man : its location in the South and on the Gulf of Mexico ; its vast extent of territory ; its rocks and great variety of soils ; its relief, which, exclusive of the Trans- Pecos mountains, ranges from a few feet on the coast to four thousand feet in the Panhandle ; its rivers, available for water power and irrigation ; its springs and artesian wells; its climate, including rainfall and temperature, winds and sunshine — a climate varying from semitropical and humid in the southeast to arid, semiarid, and temperate in the west and northwest ; its forests and other vegetation ; its native animals and game ; and its agricultural, stock, and mineral resources. Furthermore, attention will be directed to the sacrifices made by man in securing a just and stable government and to the magnificent results of his labor thus far attained as shown by the largest railroad mileage of any state in the Union, the excellent j^ublic institutions maintained, and the many beautiful cities and towns already built.

The chief source of the wealth of Texas lies in its enormous acreage of arable lands, which even now produce supplies not only for home consumption but for other countries as well; and yet their present yield but faintly indicates that of the future which, by improved methods of cultivation, will be increased many fold.

2. Location. Texas may be easily located. If a map of our country be examined we shall find, first, that, with the exception of Florida, it is the most southerly state ; and, second, that although a " Gulf state," its position is midway between the Atlantic and the Pacific oceans. If it be located on the earth's surface by means of latitude and longitude, we shall find it to lie between the parallels of 26° and 36° 30' north and the meridians of 93° 30' and 106° 30' west from Greenwich.^

3. Boundaries. A state or country is usually bounded by naming the adjoining states, countries, or bodies of water. Thus Texas is bounded on the north by Arkansas, Oklahoma, and New Mexico; on the east by Louisiana and Arkansas, and, in the Panhandle region, by Oklahoma ; on the south by the Republic of Mexico and the Gulf of Mexico ; and on the west by New Mexico and the Republic of Mexico.

The geographer may employ another method. He may bound a state without mention of the neighboring political divisions. With the map of Texas before us let us trace the boundary of the state. We may begin at the outlet of

1 Gannett, "A Gazetteer of Texas." Bulletin of the United States Geological Survey, No. 224, p. 9. Washington, 1904.

THE STATE 3

Sabine lake in the southeast. Passing northward through that body of water, we ascend the Sabine river to a poiiit where it crosses the 3 2d parallel. Here our course becomes due north until we reach the Red river. Ascending that stream until the 100th meridian is reached, we again turn due north and so continue to the point of meeting of the parallel of 36° 30', where we turn to the west. Following, now, that line until the 103d meridian is reached, we turn our faces southward and continue in that direction to the 32d parallel. Here we again change our course, following that parallel to the Rio Grande. Lastly, descending that river, we follow th3 Gulf coast to the starting point.

The Gulf of Mexico, Sabine lake and river. Red river, and the Rio Grande are natural boundaries; the lines followed, running in this instance north and south and east and west, are the surveyed boundaries.

4. Area. A glance at the map of the United States will show that Texas is the largest state in the Union. For this reason it contends with New York for the title of "Empire State." Its area is 265,780 square miles. As about 3490 square miles are covered with Avater, the land surface may be estimated at 262,290 square miles.

If we compare the area of the state with that of the United States, exclusive of Alaska and the Philippines, we shall find that it forms between the eleventh and twelfth part. If we compare it with the southern states east of the Mississippi, we shall find that it exceeds the combined areas of North Carolina, South Carolina, Georgia, Alabama, and Florida by over 12,500 square miles, or two sevenths of Tennessee. Compared with France and Germany, it exceeds the former by 61,633 square miles and the latter by 57,037 square miles.

The distance across the state in two directions, namely, from the pomt of intersection of the 3 2d parallel and the Rio Grande to that of the 31st parallel and the Sabine river, and from the mid point of the northern boundary of the Panhandle to the month of the Rio Grande, is about the same. It may be roughly stated at 770 miles.

5. Political Divisions. Texas is divided into 252 counties, of which 247 are "organized," that is, have county officers for administering the laws and for conducting their business affairs, and 5 are "unorganized," chiefly on account of the scarcity of inhabitants. The latter are in the region of the Llano Estacado, on or near the Texas- New Mexico boundary, west of the 10 2d meridian and north of the Rio Pecos. Dallas County has the largest population (135,748), and Cochran the least, 65.^ In area the counties vary greatly, from Rockwall with 149 square miles to El Paso with 5573 square miles.^ In their physical features, their products, and, in not a iew instances, their inhabitants, there is also a wide divergence ; but as these variations are usually characteristic of larger sections of the state than counties, they are susceptible of broader treatment. As a matter of fact, the county must be considered as a convenience on the part of the state, its officers as agents in the enforcement of local government.

6. Cities and Towns. There are in Texas four cities with populations exceeding seventy thousand. They are San Antonio (96,614), Dallas (92,104), Houston (78,800), and Fort Worth (73,312). There are also five cities with populations ranging between twenty and forty thousand, namely. El Paso (39,279), Galveston (36,981), Austin (29,860),

1 Bulletin of the Thirteenth Census^ 1910, "Population : Texas, Number of Inhabitants, by Counties and Minor Civil Divisions," p. 3.

THE STATE 5

Waco (26,425), and Beaumont (20,(340). Of the smaller cities and towns eleven have populations between ten and fifteen thousand, twenty have populations between five and ten thousand, and fifty-one have populations between twenty-five hundred and five thousand.^

1 Based on Bulletin of the Thirteenth Census, 1910, " Population : Texas, Number of Inhabitants, by Counties and Minor Civil Divisions."

Chapter II Geology

7. The Relation of Geology to Physical Geography. There is a close relation between the underlying rocks of a country and its surface features, such as relief, soil, water supply, mineral resources, climate, and life. If we are to understand the physical geography of Texas, we must know something of its rocks, their composition and distribution, their position, whether horizontal or inclined, their susceptibility or resistance to the eroding or carving effects of atmospheric and aqueous agents, their disintegration and decay, — in brief, we must study its geology.

8. Kinds of Rocks. Rocks may be classed in various ways. For our purpose they may be grouped into three

divisions :

1. Sedimentary or Stratified Rocks.

2. Igneous Rocks.

3. Altered or Metamorphic Rocks.

9. Sedimentary Rocks are those which have been forme 1 in water — we usually say deposited in water. They are made up of layers, or strata (singular stratum)^ and for that reason are called stratified rocks.

Some sedimentary rocks have been formed by the wasting away and decay of older rocks. Such, for example, are shale, which is hardened mud or silt, and sandstone, which is composed of grains of a hard mineral called quartz. Others have been formed from the shells and

GEOLOGY skeletons of sea and fresh-water animals, such as oysters, clams, and other mollusks, corals, and the like. By the dashing of the waves along the shore they have been broken into fragments, or even ground to a pulp. From such material limestones have been formed.

Again, far out upon the surface of the sea there are found myriads of lowly animals called foramin if ers, living in minute shells. They die and their shells fall to the bottom, where, mingled with other deep-sea deposits, they form ooze. This is the first stage in the formation of a rock called chalk, which is another kind of limestone.

It sometimes happens that water in whicli mineral matter is dissolved evaporates. When this takes place the mineral matter Avill be deposited in beds or strata. Beds of 7'ock salt and gypsum liave been formed in this way.

Of the rocks found in Texas, sedimentary rocks are by far the most abundant.

10. Igneous Rocks are those which have been formed by the cooling of melted mineral matter. Such rocks are common about volcanoes. They are also found at times filling cracks and fissures in the earth's crust. If they have been formed in masses far below the surface, they are now seen only where the overlying beds have been worn away.

As examples of igneous rocks mention may be made of granite (so named from its crystalline or grainlike structure) ; basalt, a dark volcanic rock which is cut by joints into

Fig. 1. A Fragment of Lime-

STOXE FROM ONE OF THE CrE-

TACEOus Beds of Texas

Showing the shells of a large Foraminifer named PatelUnatexana many-sided columns ; pumice^ a hardened rock froth ; and lava of various kinds.

In Trans-Pecos Texas there are lava outpourings ; on the Coastal plain a few widely separated outbreaks of basalt ; and in Burnet and Llano counties outcrops of granite.

11. Altered or Metamorphic Rocks are either sedimentary or igneous rocks which have been changed by the action of heat. They have been baked in the, presence of moisture and sometimes under great pressure. The effect of this varies with different rocks. Some are only hardened ; others are changed in a chemical way, new minerals being formed by the rearrangement of the matter of which they are composed ; and others still are altered in color and in general appearance. These are some of the results of metamorphism (change).

As an example of this change may be mentioned the hardening of some sandstones into a rock called quartzite, or the alteration of ordinary limestone into marble.

Some altered rocks break easily in the direction of their bedding, — the minerals of which they are composed are arranged in bands or layers. Such rocks are termed schists. Others break into thin plates across their bedding. They are slates.

12. The Rocks of Texas. With the exception of a small area known as the "Burnet country," or "Central Mineral region," all of Texas east of the Staked plains, as well as the region of the Edwards and Stockton plateaus, is underlain by rocks of inarine origin, that is, by sea deposits. The Staked plains, however, are capped by nonmarine deposits.

In the Trans-Pecos region of mountains and basins there are found not only marine and nonmarine deposits but also igneous and altered rocks.

GEOLOGY

13. The Geological Map. The various rock systems, arranged m the order of their age, the youngest or latest

GEOLOGICAT. MAP

OF

Fig. 2

formed at the top and the oldest at the bottom, are as follows :

1. Recent (top).

2. Neocene.

3. Eocene.

4. Cretaceous.

5. Jura-Trias.

6. Permian.

7. Carboniferous.

8. Devonian.^

9. Sikirian.i

10. Ordovician.

11. Cambrian.

12. Archaean (bottom).

Their distribution in Texas is shown on the accompanying geological map. It will be seen that they outcrop, for

1 At present not known in the state.

the most part, in a series of more or less parallel belts or strips running in a northeast and southwest direction. Moreover, until the Staked plains are reached, each belt, beginning with that bordering the Gulf of Mexico, is of a greater age than the preceding. The rocks of the Burnet

Fig. 3. Diagram illustrating the Arrangement of Strata IN THE Gulf Slope

After K. T. Hill

The layers incline or dip from the northwest to the southeast, that is, towards the Gulf. The upper surface on the left represents the outcroppings of successively older strata as the distance from the Gulf coast increases. The side view represents a geologic section in which the order of superposition of the strata is shown

country before mentioned form an exception to this statement.

14. Recent and Neocene Systems. The latest formed marine rocks are those bordering the coast. They are made up of sand, clay, and silt, and in them are found the remains of animals, chiefly shells, now living in the Gulf. This first belt, which underlies the Coastal plain, is of the Recent and Neocene systems. On account of their great similarity, they have not been separately indicated on the map.

It is well to remember in this connection that, geologically speaking, a rock need not be hard, but that any matter forming a part of the earth's crust is a rock, be it a mass of granite or a bed of sand or clay.

The Staked plains formations have also been classed as Recent and Neocene, but, unlike the preceding, they

GEOLOGY are of nonmarine origin. The Recent deposits which are here found on the surface consist of silt, sand, gravel, and sometimes bowlders. Beneath them are encountered the rocks of the Neocene system in the form of sands, clays of various colors, sandstones, and limestones.

Along the southwest border of the Staked plains the Neocene beds rest upon those of the Cretaceous, but north

Fig. 4. White Drifting Sands, Six Mii ks North of Moxahax's, Ward County

of the Double Mountain fork of the Brazos river they rest upon the Jura-Trias. Some of the strata afford fossils representing parts of the skeletons of such animals as the elephant, horse, and camel.

15. Eocene System. The outcropping beds of Eocene rocks form the second belt across the state. They are composed of sands, sandstones, claj^s of different colors from white to black, thin-bedded limestones, etc. Beds of lignite^ an inferior kind of coal, are often found.

The lignite beds are usually lens-shaped — thick in the middle and thinning out towards the margin — and of limited extent, thus differing from true coal seams which usually form continuous layers over large areas. In some instances the lignite beds have a thickness of twelve or more feet.

Petrified wood and gypsum are also found in the Eocene formation, and in East Texas beds of workable iron ore. The presence of oil and natural gas should also be noted.

16. Cretaceous System. Further inland the outcropping Cretaceous rocks form a rather broad band stretching from

the Red river to the Rio Grande.

Viewed as a whole they are limestones, but there Fig. 5. Ram's-Horn Oyster {Exogyra ariethia) are also beds of

This fossil, characteristic of the Delrio formation Sand, clay, and of the Texas Cretaceous, occurs in great abun- gJ^r^J^g Some of the dance at several points on Shoal creek, Austin

chalky beds contain the remains of forammifers. Other limestones are composed of mollush shells, either whole or in a fragmental state. In short, we find in the rocks of this system both deep-sea and shore deposits.

The Black and Grand prairies, as well as the Edwards plateau, are underlain by Cretaceous limestones. Cretaceous sands are the reservoirs of a large artesian water supply ; and an upper member of the system, the Taylor formation, is the source of oil at Corsicana.

17. Jura-Trias System. Skirting the eastern scarp of the Staked plains there is a narrow band of nearly horizontal strata composed of sandstone and a coarse pebbly rock

GEOLOGY 13

called conglomerate^ together with clay. Its proper position is between the rocks of the Permian system and those of the Cretaceous. Generally speaking, however, it appears between the Permian rocks and the Staked plains formations already described, the Cretaceous rocks being absent.

18. Permian System. Rocks belonging to the Permian and Carboniferous systems appear, for the greater part, in a basin lying between the Staked plains and the Grand prairie (consult the relief map). The line of contact between them is not yet well established. Beds that have hitherto been called Permian occupy the western and larger part of the basin. Here are found clay, sand, limestone and gypsum deposits. On account of their widespread red color they are usually spoken of as the " Red beds." The occurrence of Permian rocks in the Guadalupe mountains and in their southeastern extension, the Delaware mountains, Culberson county, has been recently reported.

19. Carboniferous System. These rocks form the " buried floor" upon which the Cretaceous rocks were deposited. They consist of limestones, shales, and sandstones, together with seams of coal, several of which are valuable. Beds of clay are also found. The term *' Coal measures " is often applied to these rocks. Carboniferous deposits are also known in the Hueco and Diablo mountains and at other points in the Trans-Pecos country.

20. Ordovician and Cambrian Systems. The oldest stratified rocks found in Texas occur in two rather limited areas — one near El Paso, and the other near the center of the state surrounding exposures of granites and schists. In the last mentioned resfion the Ordovician rocks are in the form of thick, heavy-bedded limestones, while those of the Cambrian are chiefly sandstones alternating Avith limestones.

21. Archaean System. Beneath the rocks of the Cambrian system there is a series of beds which have been named the " Llano group." It consists of schists and other altered rocks which, with the underlying and intruded granites, represent the Archaean system.

Granite is a rock made up of quartz, feldspar, and mica. The feldspar is often of a pinkish color, and it is this mineral which gives to the Capitol at Austin its peculiar tint. The quartz is sometimes glassy and transparent, or it may be of a milky-white color. In the Capitol granite the mica is of the black or biotite variety and may be easily recognized by its thin scaly layers. When visiting the Capitol, its large, highly polished corner stone should be examined.

Chapter III Relief And Soils

22. Classification. The inequalities of the earth's surface, such as its slope, undulations, hills, mountains, plateaus, and valleys, constitute its relief. From this point of view Texas may be divided into the following regions :

1. Gulf Slope.

2. Central Basin.

3. Plateaus.

4. Mountains and Basins.

23. Region of the Gulf Slope. This region, which includes that part of the state lying to the south and east of the Central basin and the Edwards plateau, may be separated into the following divisions :

a. The Coastal Plain.

h. The Forested Area.

c. The Rio Grande Plain.

(l. The Black and Grand Prairies.

24. The Coastal Plain skirts the Gulf. It is a low, flat, and, generally, treeless region. For this reason it is often called the Coast prairie. On its outer margin it rises twenty to thirty feet above the sea, gradually increasing in elevation towards the interior. Its width on the Sabine river is about thirty miles, but it widens to the westward, reaching a hundred miles or more on the Brazos and Colorado rivers. Beyond the latter river it merges with the

Rio Grande plain from which it is separated by an indefinite and somewhat arbitrary boundary, the chief distinction being of a geologic character. That which is here designated as Coastal plain is underlain by the latest formations o o o w

Fig

6. A Relief Map of Texas on which the Chief Topographic Divisions are indicated

From a Relief Map of the United States modeled by Edwin E. Howell. Copyright, 1892. Used by permission

— the Recent and Neocene — while the Rio Grande plain, which extends from the coast to the base of the Cretaceous highlands, is underlain not only by these but by earlier

RELIEF A^D SOILS formations (see Fig. 2). Though crossed by many streams, the drainage of the Coast prairie is poor. The water ways are but a few feet below the general level, and between them there are many swampy intervals. It is an excellent example of a recently formed plain.

Deltas. The effects of recent stream building are apparent at several points along the coast, giving rise to " delta shore lines."

The waste of the Rio Grande has produced a marked outward encroachment upon the waters of the Gulf, and the combined action of the Colorado and Brazos rivers has given rise to a similar though not so conspicuous result. The Trinity river, which empties into Galveston bay, has formed a true delta with distributaries. So great is the accumulation here that the delta deposits now extend nearly across the head of the bay, cutting off a body of water called Turtle bay, as shown in Fig. 8.

Peninsulas and Islands. The conflict between the sea and the land has given rise to the long narrow peninsular and island barriers fringing the Gulf coast of the state, so admirably exemplified in Matagorda peninsula and Padre island.