12 COLORADO COLLEGE STUDIES. 



springs and salt-marshes at and north of Geuda Springs in 

 Sumner county, and southwest of Arkansas Cit}- in Cowley 

 county, are also within this belt. Various geographic 

 names in this belt have been taken from its geological 

 peculiarities. Thus there are several streams called Gyp- 

 sum creek, a Gypsum township, and even a Gypsum City; 

 the two Slate creeks of Sumner county take their name 

 from slate-colored shales which belong, in the case of the 

 larger stream partly and in the case of the smaller one 

 wholly, to the Geuda measures; Bitter creek, in adjoining 

 parts of Sumner county, Kansas, and K county, Oklahoma, 

 and mtermediately the Bitter Creek postoffice, Geuda 

 Springs, and its now abandoned neighbor. Salt City, are all 

 named or, in the case of Geuda Springs, best known from 

 peculiarities of these measures. At Geuda Springs, are 

 several mineral springs differing in the analyses of their 

 several waters, but all belonging to the saline class. These 

 and the salt-marsh of the same locality and the beds of 

 gypsum and limestone not far away, present a fair epitome 

 of the characteristics of the Geuda outcrop. 



The shales of the Geuda outcrop are blue, gray, slate- 

 colored, drab, buff, red and various shades of bluish and 

 brownish red. In the deepest known parts of the Geuda 

 the three first-named colors prevail. 



The limestones of the Geuda are in part unfossilferous, 

 but those in the lower and sometimes those in the upper 

 part of the formation contain a fauna from which 

 brachiopods and essentially Carboniferous fossils are 

 all but wholly excluded, and which, indeed, consists 

 almost entirely of Lamellibranchia of recognized Per- 

 mian affinities. The writer has personally identified 

 only a few of the fossils of these limestones, and some 

 of the determinations recorded by the earlier writers on 

 this part of the Kansas section have need of verification or 

 require revision of synonymy. We therefore present here 

 the list of fossils recently recorded from these limestones by 



