South Dakota School of Mines 29 



Section Near Florman's on West Side of Slim Buttes. 



Soil and soft white sandstone 20 feet 



Hard layers of sandstone forming a cornice and a 

 layer six inches thick at the top, very hard 



like flint 5 " 



Sandy white clay, cracking polygon-ally above, shad- 

 ing into thin white sandstone below 12 " 



Massive white, fine sandstone with small globular 

 concretions, translucent within, the rock show- 

 ing efflorescence where not exposed to the 

 weather. There are eiome layers of reddish color 



and some even shaly 60 " 



Reddish flat concretions 1 " 



Stratified, white sandstone 6 



Soft sandstone, <full of vertical, stalactite-like con- 

 cretions, redder below 6 



Massive argillaceous sandstone, weathering into glob- 

 ular masses and containing email globular 



concretions 15 



Slope mostly soft white sandstone 27 



Gray clay with porous sandstone fragments and with 

 several thin interrupted layers of sandstone ob- 

 liquely laminated, usually dipping to the north. 18 " 

 Rusty clays and sand, eiome white places and occas- 

 ional thin layers of limonite 10 " 



Total 180 feet 



Section in the Southeastern part of Slim Buttes. 



Clay, top of it flat with fragments of limestone. . . 9 feet 



Coarse sandstone 2 " 



Whitish clay 3 8 " 



Light gray sandstone 4 



Fine argillaceous sand rock 50 



Coarse sandstone 9 



White' argillaceous limestone, lower six inches full 

 of fossils of .fresh water shells, very hard and 



sonorous 2 to 3 



White clay , 18 " 



Sandy w r hite clay • 8 " 



Fragments of buhrstone or yellow flint with plant 



stems 1 



Total 142 feet 



Farther south, according to Darton, "Castle Rock is capped 

 by no feet of Tertiary deposits lying on dark-gray clays. At 

 the base are thirty feet of mostly fine white sandy massive clay, 

 merging downward into five feet of grayish-green sandy clay. 

 The upper 75 feet is of sandstone, mostly soft, but partly quart- 

 zitic, as a rule massive, but in places thin bedded and with a 

 few pebbly layers. In some respects it resembles portions of the 

 White River formation (Oligocene) of the Big Badlands, but 

 the entire deposit or at least its upper member may be an out- 



