260 GEOLOGY OF THE BLACK HILLS. 



birch, hazel, and hornbeam. The greater portion of this area of slates is 

 drained by the numerous branches of Whiskey Creek, a small stream with 

 from 30 to 50 miner's inches of water (July 20) flowing' east from the 

 Harney Peak range, about six to eight miles south of Spring Creek, and 

 sinking before it reaches the plains. Near the head of this stream, at the 

 junction of the granite with the slate formation, a huge mass of slates, 

 standing on edge, 30 feet in height, was observed projecting from a crag of 

 feldspar granite. The fragment of slates was only partly inclosed in the 

 granite, so that the north side of the lenticular peak was composed of slates, 

 while the south was wholly granite. It was probably a "horse" in the 

 granite dike. In the southeastern part of this area, near the foothills, is 

 quite an expanse of Potsdam sandstone and Carboniferous limestone, but 

 near where the water sinks in Whiskey Creek the limestone belt encircling 

 the Hills is not more than a mile in width. With the exception of the pres- 

 ence of granite peaks among the slates, the general character of the rocks 

 is similar to that of the Spring Creek Valley, and fine crystals of stanrotide, 

 mostly twins in lamellar schists, resembling the specimens of that mineral 

 from Lancaster, Mass., were found near the granite ridges. In the lower 

 part of the valley of Whiskey Creek small gravel benches occur along its 

 banks, but gold was not discovered in paying quantities except below 

 where the water sinks in the bed of the stream among the limestone Red 

 Bed formations of the foothills. 



From the fact that the area drained by this stream is almost identical 

 in the character of the rocks with that of the Spring Creek district, although 

 less extensive, I consider that there are good reasons to expect that, at least 

 in some localities, gold may be found in paying quantities in the gravel 

 deposits of Whiskey Creek and its tributaries. 



The gold deposits discovered in the dry ravines and arroyos among 

 the Red Beds where the dry bed of this stream winds through the low hills 

 at the edge of the plains will be described in the section on The Deposits 

 of Auriferous Gravel in the Foothills. 



