10 The American Geologist. Jan- i89o 
topography, with its unique geology and is radically different 
from the section first mentioned ; the extreme northwestern 
corner, or the Panhandle, is the southern end of the great 
plains, familiar to us in their northern extent through Col- 
orado, Kansas and Nebraska. Between these diverse regions 
— the cotton belt, the Rocky mountains and the Great Plains — 
and entirely surrounded by them, lies the main portion of the 
state, exceeding all others in area, and so incomparable to 
any other portion of the United States that it is peculiarly 
worthy to be called Texan. It possesses almost as great a 
diversity of geologic and topographic features as all the others. 
To scientifically differentiate and define this Texan region 
and establish for it a proper appreciation in the minds of our 
geographers and geologists is the object of this paper. 
Topographically the Texas region consists of a series of 
extensive, elongated parallel benches and plateaus, extending 
approximately in a north and south direction, and abruptly 
terminated at each end by great mountain systems extending 
at right angles to them — an arrangement comparable to a wide 
stairway, in which the plains are represented by the steps, 
and the mountains by the enclosing walls. This analogy can 
not be carried far, for great irregularities and depressions 
will be found in the width and tread of the steps, and the 
structure of the mountains, which represent the enclosing 
walls, is of two entirely different schools and periods of arch- 
itecture. The wear and tear of time has scarred aiid disfig- 
ured the region, leaving footprints where the drainage or other 
erosion has crossed the plains and worn the mountain walls. 
In this paper it is proposed to classify these features in the 
sequence of topographic origin, as follows: (1) Plains. (2) 
Valleys, or depressed areas produced by the erosion of plains. 
(3) Mountains, which may be considered disturbed and 
crumpled plains. 
(1). The Plains of Texas. 
The steps, or plains, with one exception, are treeless, and 
upon close examination, prove to be a series of ancient base 
levels, which have been elevated more or less rapidly and in- 
termittently in post Cretaceous times. These increase gradu- 
ally in altitude towards the interior, varying in bight from 
sea level to more than three thousand feet. Beginning at the 
coast these may be temporarily classified as follows : (1) 
