46 COLORADO COLLEGE STUDIES. 



several of his earlier geological reconnaissances of Clark 

 county and the formerly so-called Public Lands, it is pro- 

 posed to call this interesting lithologic occurrence, or rock- 

 variety, Faresite. 



THE HACKBERRY SHALES. 

 In Clark county, Kansas, the Day Creek dolomite is 

 overlaid by 15 to 20 feet of crumbling, chiefly maroon-col- 

 ored shales, including some moderately hard lamina' that in 

 weathering check into small cakes and dice-like chips. 

 They are well shown in the region of the junction of 

 Hackberry and Bluff creeks, from the former of which they 

 derive the name of Hackberry shales. They follow thence 

 the irregular westerly course of the Day Creek outcrop to 

 the western part of the county. The most westerly occur- 

 rence of the Hackberry formation that has been satisfactor- 

 ily identified by the writer is in the southeastern wall of Big 

 basin ; but the writer has observed what he is inclined to con- 

 sider as remnants of it on lower Crooked creek, at and above 

 Odee, while the dolomite of G^^psum Creek on the Clark- 

 Meade county border, if referable to the Day Creek terrane, 

 involves the not unlikely occurrence of the Hackberry 

 shales with it. 



THE BIG BASIN SANDSTONE. 

 The western, northern and northeastern parts of the 

 bluffy walls of Big basin are formed largely by the calcar- 

 eous sandstont- of the Loup Fork; but on the easterly to 

 southeasterly quarter the rim of the basin is chiefly of Kiger 

 sediments, in which the Hackberry shales appear with a 

 coping of rather massive, blocky, red and grayish-white 

 sandstone. The latter, from this locality of its typical oc- 

 currence, may appropriately be known as the Big Basin 

 sandstone. It is also seen on Kiger creek, at the Fares ranch 

 on West Bear creek, and elsewhere in Clark county. Its 

 maximum thickness probabl}' does not anywhere exceed 12 

 feet. While particolored, it has less of the "poikilitic" char- 



