28 COLORADO COLLEGE STUDIES. 



of red clay, the Jenkins day (named after the former Jenkins 

 postoffice, near Cave creek), 7 to 10 feet. 



The Medicine Loikje Gypsum. — While the Shimer 

 gypsum and the Jenkins clay re([uire merely brief notice 

 here, the former resembling the Medicine Lodge gypsum 

 and the latter the commoner gypsiferous red clay-shales of 

 the Salt Fork division, the Medicine Lodge gypsum calls 

 for a special description, on account of its stratigraphic im- 

 portance and its more than ordinarily interesting general 

 character. 



If, on the road from Harper to Medicine Lodge, the 

 traveller linds himself looking westward across the valley 

 of the Medicine Lodge river on one of those enchanting 

 days for which southern Kansas yields the palm to no 

 other locality, the autumn air being tinged with just enough 

 of haze to purple the remoter vistas of the ruddy landscape, 

 " The splendor falls on castle walls " 



which rear themselves seemingly as low mountains or 

 buttressed escarpments of a table-land crowning the further 

 incline of the valley and bounding a considerable part of 

 the western horizon. 



These are the Gypsum hills. They are a northern 

 extension of those on the Red and Canadian rivers, observed 

 by Marc}' in his Red river expedition of 1852 and earlier 

 reconnaissance, and illustrated in the report of that expedi- 

 tion in 1854. 



The earhest geological study of the Gypsum hills of 

 Kansas was made in 1884 by the writer, who gave an 

 informal description of them before the '84 meeting of the 

 Kansas Academy of Science at Lawrence, publishing a 

 sketch of their physical geology a few months later in the 

 Bulletin of the Washburn College Laboratory of Natural 

 History.* 



*No. 3; published about May 1, 1885. 



