238 GEOLOGY OF THE BLACK HILLS. 



The water-supply at the head of French Creek was very small and 

 uncertain, totally inadequate for extensive working of the gulch, while the 

 flatness of the valley is also a serious obstacle to the successful working 

 of the gravel bars if water should be brought from Castle Creek for that 

 purpose ; which cannot be done until the richer deposits on that creek are 

 exhausted. 



Above the stockade there are localities where the gravel will pay fair 

 wages for sluicing, using the limited water-supply of the creek and work- 

 ing only the richest places in the beds I regard the poverty of the French 

 Creek deposits, compared with those afterward discovered on the streams 

 farther north, to be due to a deficiency in the source of supply, owing to 

 the small area drained by the stream, the small amount of denudation to 

 which the ledges in this area have been subjected, and to a want of suffi- 

 cient grade in the valley to cause a concentration of the gold into a pay 

 channel. 



Had all the gold diffused through the valley of French Creek been 

 concentrated into a narrow lead or pay channel, it would have made claims 

 as rich as the most enthusiastic miner would have desired. 



SECTION III. 



SPRING CREEK DISTRICT. 



Spring Creek rises among the parks in the central portion of the Hills 

 to the west and northwest of Harney Peak, and is formed by the union 

 of a number of small brooks, some heading in the limestone at the western 

 edge of the Beaver Creek Plateau, others in the granite of the Harney Peak 

 range, or with numerous ramifying branches drain the schistose rocks of 

 the parks. 



Just below where the main branch, flowing from the south, rising 

 among the granite and metamorphic schists of the parks, unites with New- 

 ton's Fork, coming from the talcose and quartz schists in the direction of 

 Castle Creek, a remarkable change is seen in the topography of the region 

 and the character of the rocks ; and Spring Creek, becoming a fine and 

 rapid stream, heads eastward into a new geological formation — the second 



