6 COLORADO colle(;e studies. 



ferous, together with several hundred feet of the un- 

 mixed Permian, having its base a few feet above the Cot- 

 tonwood hmestone of Prosser (Fusulina Hmestone of Swal- 

 low) and its upper Hmit at the summit of the Wellington 

 shales. It may be called the Bi;/ Blue series, from the l)ig 

 Blue river, which in northern Kansas crosses the some- 

 what narrowed northern extension of its area of outcrop, 

 cutting both of its divisions*. Its rocks include variously 

 colored, in part gypseous and saline shales, hmestones 

 many of which are either siliceous or marly, rock-salt, 

 gypsum, and occasional beds of conglomerate. The shales 

 are drab, yellow, greenish, chocolate, maroon, red, white, 

 gray, blue, and dark slate-colored; but other than red in 

 the greater part. The series contains the extensive rock- 

 salt deposits of central and southern Kansas that have be- 

 come of so great commercial importance within the past 

 few years, and whose products have been manufactured at 

 Hutchinson, Kingman, Kanopolis, Lyons, Anthony, and 

 other towns of that region. 



In its lower portion, the Big Blue series is charac- 

 terized by both Carboniferous and Permian fossils; in 

 higher horizons, by Permian fossils only; and in its upper 

 portion, is devoid of organic remains, so far as at present 

 known. 



It embraces two divisions; the lower, or Flint Hills; 

 and the upper, or Sumner. 



THE FLINT HILLS DIVISION. 



This division of the Big Blue series takes its name 

 from the great monoclinal ridge, called the Fhnt hills, 

 that extends from the northern part of the Osage Nation 

 northward along the eastern border of Cowley and But- 

 ler counties, Kansas, its rocks forming an important part 

 of the ridge and the highlands that constitute in Chase, 

 Morris, Riley and other counties, its dissected northern 

 and northeastern extension. Of these "Permian mount- 



