J 
Hill—Outlying Areas.of the Comanche Series, etc. 205 
Art. XXI.—On Outlying Areas of the Comanche S-ries in 
Kansas, Oklahoma and New Mexico; by BR. T. H1u.* 
THE Tertiary Plains formations of western Kansas, Texas and 
eastern New Mexico constitute the summits of extensive levels 
or plateaus. The eastern border has an average altitude of 
2000 feet in Kansas and 2500 feet in Texas. 
The Medicine Lodge, Cimarron, Canadian, Red, Brazos, aud 
Colorado rivers originate along the eastern escarpment of the 
Great Plains and are rapidly destroying them by head-water 
erosion. These streams are types of the valleys of the rivers 
of the central denuded region which rise in the eastern margin 
of the plains, as distinguished from the rivers of the plains 
such as the Republican and Smoky Hill, which rise and flow 
upon the plains formations, and from the rivers of the moun- 
tains which transect the plains. 
The sources of these marginal rivers consist of many digi- 
tate branches along the eastern border of the plains. These 
streams soon cut through the Tertiary formations composing 
the surface of the plains, down into the underlying red beds 
of undetermined age, which are the chief components of the 
underlying floor. These valleys are bordered by mural escarp- 
ments of red beds, capped by remnantal patches of the Plains 
formation between which are preserved occasional patches of 
the Cretaceous formations. 
In proceeding southward the first region of the breaks of the 
plains with their escarpments of picturesque Red Bed scenery, 
is the valley of the Medicine Lodge River of Kansas—the 
so-called “ Gypsum Hills” country of many writers. 
This region, which lies along the south central border of 
Kansas in the counties of Harper, Barber, Comanche and 
Meade, abounds in data throwing light upon the problems of 
the Pleistocene, Tertiary, Cretaceous and Permo-Trias history. 
Its geology has been mentioned by earlier writers, especially 
Professors O. P. St. Johnt and Robert Hay.t The latter has 
given an interesting and graphic description of the structure 
and scenery and pointed out the great denudation which pre- 
ceded the Tertiary sedimentation. 
Near the head-waters of this river a thin group of Creta- 
ceous formations lies between the Tertiary and the Red Beds. 
To the east the Plains formations rest directly upon the Red 
* Published by permission of the Director of the United States Geological 
Survey. 
+ Notes on the Geology of Southwest Kansas, by O. P. St. John, Fifth Biennial 
Report, Kansas State Board of Agriculture, Topeka, 1887, Part II, pp. 132, 152. 
t A Geological Reconnoissance in Southwestern Kansas, by Robt. Hay, Bull. 
.57, U. 8. Geological Survey, 1890. . 
Am. Jour. So1.—Ts1IRD SERIES, VOL. L, No. 297.—SEPTEMBER, 1895. 
