112 KANSAS ACADEMY OF SCIENCE. 



Lying near their center, in southern Missouri, eastern Arkansas, and 

 the Indian Territory, is an area which has a mountainous structure. 

 As a result of continuous erosion by streams since the establishment 

 of the drainage system of the Mississippi valley, the Prairie plains 

 encroach upon its flanks. Another factor in the development of the 

 Prairie plains was the advance and retreat of the ice sheet which cov- 

 ered their northern portions in glacial times, sculptured the surface, 

 and left behind upon its retreat vast accumulations of rock material. 

 This portion of the Prairie plains is known as the glaciated, in con- 

 trast to the southern, or non-glaciated, division of the region. 



To the west of the small area of the Springfield plain in the south- 

 eastern corner of the state there is a belt of low-ljang country known 

 as the Cherokee lowland. This area continues in Missouri, and has 

 there been called the Nevada lowland ; it also extends into Indian 

 Territory along the valley of the Neosho or Grrand river, where it merges 

 with the lowland plain of the Arkansas Valley region. The lowland 

 is developed on the soft shales and sandstones which form the base of 

 the Coal Measures in Kansas. The shales have a thickness of about 

 450 feet, and are exposed over a belt of country approximately twenty- 

 five miles wide, within which are situated Cherokee county and por- 

 tions of Crawford and Labette. In Missouri the area tapers to a point, 

 as a result of the overlapping of the higher beds which form its west- 

 ern border onto the rocks of the Springfield plain. 



The surface ie gently undulating, the monotony of lowland topography being 

 occasionly broken by ridges and mounds which occur on the divides and owe their 

 existence to heavy sandstones. Such a mound is the one west of Baxter Springs, 

 near the territorial line. The country around Columbus exhibits a number of 

 sandstone ridges, the city being located upon the divide between Spring river and 

 the Neosho. . . . The western border of the Cherokee uplands is the O-swego 

 escarpment, which is produced by the first important limestones in the Kansas 

 section of the Coal Measures. This formation is known as the Fort Scott lime- 

 stone, and at Oswego caps a bed of shales, producing an escarpment which along 

 the river bluff is 120 feet high. (Adams, Physiography of Southeastern Kansas, 

 Kan. Acad. Sci., vol. XVI, p. 57.) 



The surface of the lowland is gently undulating, with watercourses flowing in 

 wide, flat-bottomed valleys bordered by low, gentle slopes. Toward the western 

 side of the valley outliers of the escarpment bordering the northwestern side re- 

 lieve the general monotony of the landscape. The whole area is practically down 

 to grade. It is already a lowland of denudation. It has long since passed through 

 its stage of most pronounced relief and is now gradually wiping out the varieties 

 of its surface. On the softer rocks, in the vicinity of Clinton, the general level 

 is in many places less that fifty feet above the level of the flood plains of the 

 streams. . . . The area of the soft beds has been exposed to degradation no 

 longer than that of the hard limestones comprising the Springfield structural 

 plain, yet the soft ones have reached old age in the cycle, while the harder ones 

 are in a vigorous youth. (Marbut, Mo. Geol. Surv., vol. X, p. 67.) 



