20 The American Geologist. 'an. is'jo 
the whole area, however, is a level plateau, which could be 
considered a mesa were it not for the continuity beneath the 
Staked Plains of a small portion along the drainage divide of 
the Colorado and Pecos. The central portion of the northern 
area is prolonged westward up the drainage divide of the 
Brazos and Colorado, for nearly two hundred miles, approx- 
imately following the 32nd parallel, in a narrow irregular strip 
of flat topped buttes and mesas. 
The stratification of the Grand Prairie is almost horizontal, 
except along the southeastern border in the disturbed region 
of the Balcones, it approximately corresponds in inclination 
with the plateau. In color, composition, and scenic aspects 
these rocks and their stratification resemble no other region 
of North America, but I am informed by many reliable gen- 
tlemen of culture who have migrated into the region from 
western France and Switzerland that they are almost identi- 
cal in aspect to the Cretaceous and Jurassic rocks of their 
native lands, a coincidence which is here given for what it is 
worth. To this structure and its method of disintegration is 
due the individuality of the topography of the Grand Prairie, 
and their extent is coincident. 
The western border of the Grand Prairie is especially inter- 
esting and unique. Like that of the Black Prairie it is a 
scarp of stratification, but it would take the pen of a Dutton, 
or the brush of a Holmes to picture the superb carving and 
stratification of its beautiful topography. The edge of the 
surmounting plateau is from three to five hundred feet above 
its base, and everywhere overlooks the lower and different 
region upon which it borders. Owing to the innumerable 
alternations of hard and softer layers it presents a series of 
persistent benches and terraces of stratification which are 
uniform in contour and extent, and an imitation of Avater- 
made terraces.'^ 
The line of this escarpment is very irregular, forming innu- 
merable curves and points. Sometimes it follows the tran- 
secting rivers until almost the eastern margin of the region is 
^ This topography is fairly represented upon the topographic sheets 
of the U. S. Geological Survey, especially the Gatesville and Burnet 
sheets. The principles of its 'formation are descrihed in cliapter iii of 
that admirable treatise "Les Formes du Terrain," by De la Niie and 
De Margerie, while the illustration of the valley of the Bienne, in 
Jura, on plate vi, is a perfect picture of the feature under discussion. 
