314 GEOLOGY OF THE BLACK HILLS. 



tracts being most valuable for grazing purposes, will not be used for cul- 

 tivation. 



Even a casual examination shows that the soil of the valleys, the broad 

 swales of the parks, and the bottom lands along the creeks is exceedingly 

 rich and deep, being a dark-colored loam, resulting from the decomposition 

 of the granite, limestone, and schistose rocks occupying the central area of 

 the Hills. Often in sinking prospecting pits along the valleys in search of 

 gold, the soil would be found to be a black peaty loam, from 2 to 3 feet in 

 thickness, and frequently in the bottom-lands the soil was 4 feet in depth, 

 resting on a gravelly subsoil. 



In the parks and along the elevated limestone divide near Crook's 

 Tower are numerous swales of rich grass-land between the low hills and 

 ridges. The soil is deep and fertile, supporting a rank growth of herba- 

 ceous plants, but owing to the elevation above the sea and the short grow- 

 ing season of not more than three months the value of these tracts for cul- 

 tivation has yet to be proved by experiment. In the valleys of Spring and 

 Rapid Creeks are extensive bottom-lands, which would be excellent for 

 farming purposes did not the underlying gravel contain gold in quantities 

 sufficient to cause it to be mined out in the next few years, to the ruin or 

 serious detriment of the land. 



The whole valley of Rapid Creek, a mile and a half wide, from the 

 foot-hills to the Cheyenne, a distance of 45 miles, is susceptible of irriga- 

 tion from the stream, which carries at least ^,000 miner's inches of water in 

 midsummer. The soil of this valley is deep and fertile, except near the 

 Cheyenne, among the clay-shales of the Cretaceous, where the presence of 

 alkali makes the grass thin and poor. 



There are extensive tracts of good farming lands on the Redwater and 

 Spearfish where they unite to form the Deep Water, a branch of the Belle 

 Fourche. Colonel Dodge, the commander of the escort, regarded this 

 locality as admirably suited for a military post. 



The soil of the upper valley of the Belle Fourche, from Bear Lodge 

 Butte to the point where it suddenly bends to the southeast, is reported by 

 the topographical party to be excellent, and that broad flats of grass-land 

 skirt its banks for miles. The valley of this stream below where it is joined 



