28 TJie America?i Geologist. January, 1900 
sandstone and sandy shale than is seen at Belvidere. The 
presence of gypsum is also more noticeable. In the lower part 
of the formation diamond shaped crystals of selenite predomi- 
nate. These vary from one-half inch to more than a foot in 
length. Toward the upper part of the formation the selenite 
is replaced by cone-in-cone gypsum which lies in ledges several 
inches thick. 
2. Fossils. 
The fossils of the Clark county locality do not differ ma- 
terially from those at Belvidere. For a list of the same the 
reader is referred to page 23. 
c. The Medici7ie Beds and Dakota Sandstone. 
I. Stratigraphy. 
The Kiowa in this locality, in its upper part, grades through 
the Medicine beds into the overlying Dakota. The divisions' 
of Spring Creek, Greenleaf and Kirby are not so well marked 
as on the Medicine river, nevertheless they are observed in 
many localities.* The Dakota lies in a line extending north- 
east and southwest across the heads of numerous ravines and 
creeks from ten to fifteen miles northwest of Ashland, the 
county seat of Clark county. Beginning near Messing's ranch, 
outcrops may be see on the slopes of Hackberry, East Bear, 
West Bear, Chatman, Sand and Kiger creeks. The most 
western exposures were found in the walls of the Little Basi-i 
eighteen miles northwest of Ashland at a point only a few 
hundred yards from the most western exposures of the Kiowa. 
Dicotyledenous leaves have been found in all the above men- 
tioned localities. 
The culmination of the Dakota of the locality is in the 
Cheyenne canyon near the head of West Bear creek, twelve 
miles northwest of Ashland and six miles northwest of the old 
Fare's ranch. The locality has been referred to by professor 
Cragin who assigned to the Dakota rocks a thickness of forty 
feetf, and by Prof. Prosser w^ho measured seventy-five feet J 
♦American Journal Science, vol. V, pp. 172-173. 1898, sections IV 
and V. 
ILoc. cit., p. "]"]. 
JLoc. cit., pp. 162-164. 
