116 KANSAS ACADEMY OF SCIENCE. 



but few rolling areas anywhere within the Carboniferous. The tributaries of the 

 different streams have cut the whole country into valleys, apd the residual por- 

 tions, which have not been carried away by erosion, constitute the hills, so that 

 usually there is such a succession of hills and valleys that the whole country is 

 not only well drained, but moderately rugged. While one may travel for miles 

 in the direction of the ridges almost on a level, in a transverse direction deep 

 valleys will be found. (Haworth, Univ. Geol. Surv. Kan., vol. I, pp. 213-215.) 



The sandstone beds, which give rise to heavy escarpments in the 

 Osage prairies in the Indian Territory, are succeeded in eastern Okla- 

 homa by softer beds and a succession of formations, which, being 

 generally homogeneous in character, do not give rise to escarpment 

 features. The portion of the Prairie plains lying in eastern Okla- 

 homa may be characterized as the rolling plains, in contrast with the 

 terraced surface of the Osage prairies. To them the name Oklahoma 

 prairies is here given. The area is traversed by streams which flow in a 

 general eastward direction, but whicli are deflected toward the south. 

 The divides are gentle, and no very decided differences of elevation 

 exist throughout the area. The country rock and soil of this area are 

 generally red, and are a portion of what has been called the Red Beds, 

 which are a color phase of the Carboniferous and Permian formations. 

 The western limit of these prairies is marked by a conspicuous es- 

 carpment, known as the Gypsum Hills escarpment, which passes 

 from the Glass mountains, on the Cimarron river, in Oklahoma, to 

 the west of Alva, and thence into Barber county, Kansas. Only a 

 small portion of the Oklahoma prairies lies in the state of Kansas. It 

 is triangular in form, and includes the western part of Sumner and 

 Sedgwick counties, and a portion of Harper and Kingman. The line 

 of division between the Oklahoma prairies and the Great Bend low- 

 land is naturally not well marked by topographic features, but is 

 drawn relative to the area over which the streams have migrated as a 

 result of the local base-leveling of the Arkansas river. 



The Arkansas river along its course in Kansas, where it makes 

 what is known as the great bend, flows in a shallow channel. Its 

 valley comprises a broad stretch of generally diversified lowlands, 

 which represents a local base-level of the stream. In this portion of 

 its course the river lies on the easily eroded Paleozoic shales and the 

 shaly beds of the Dakota formations, and, together with its tributary 

 streams, has, in the course of its meanderings, reduced the country to 

 a generally level plain. The western limit is found along the course 

 of the stream from Larned to Great Bend, where it impinges against 

 the Dakota sandstones. Its southern limit lies in Oklahoma, where 

 the river, in passing around the southern end of the Flint hills and 

 eroding its channel across resistant beds, has been confined to a 

 narrow valley. The area of the Great Bend lowland is largely covered 



