278 GEOLOGY OF THE BLACK HILLS. 



slowly climb the opposite side, at last reaching the top of the divide 

 exhausted and out of breath, only to find that you are on the crest of 

 another similar ridge ending in a few hundred yards ; to continue this 

 wearisome march for hours and only travel four or five miles in a straight 

 line; such was one day the experience of the party on Bear Butte Creek. 



The more mountainous character of the country and the greater prev- 

 alence of limestone in the area drained by Spearfish Creek make the canons 

 on that stream the deepest and longest found in any part of the Hills. One 

 of the parties exploring Spearfish entered the main canon near its source to 

 the north of Crook Tower, and, being unable to extricate themselves and 

 horses, were obliged to force their way through its whole length to where it 

 opens out into Redwater Valley, some thirty miles from its head. Most of 

 the distance they waded their horses down the bed of the stream, which in 

 a swift current flowed over smooth limestone rock. In places the vertical 

 cliffs of the canon rose from the water's edge, and nowhere did they find a 

 place where the cliffs could be scaled without abandoning the horses. The 

 party reported that the rocks seen were mostly limestone A narrow belt 

 of slates for some distance forms the base of the cliffs, the tops being Pots- 

 dam sandstone or the limestone of the Carboniferous. This is also true 

 for those branches of Spearfish rising near Terry Peak, where the Pots- 

 dam covers quite an extensive area, while the narrow canons are cut 

 through it into the slates. 



Near Black Butte, at the mouth of Spearfish Canon, the limestone 

 forms the west wall of the main gorge, while the eastern branches drain a 

 very mountainous track, consisting mainly of igneous rocks. Spearfish 

 emerges from the cafion with a swift current, equaling, if not exceeding, 

 Rapid Creek in volume of water, and, emptying into the Redwater, forms 

 by the union a fine river, a branch of the Belle Fourche, known to the In- 

 dians as Deepwater. 



Just above the mouth of the canon several small streams enter Spear- 

 fish from the southwest, heading in the ridge between Spearfish and Floral 

 Valley. On these branches a party of miners discovered rich placer de- 

 posits the past summer which have since been more fully prospected and 

 developed. Wishing information in regard to the location of the new dis- 



