GEOLOGY OF THE BLACK HILLS. 



By Henry Newton. 



CHAPTER I. 

 INTRODUCTION. 



Situation and relations of the Black Hills. — Historical Sketch of Explorations in the Up- 

 per Missouri Region. — Discoveries of Gold in the Black Hills. — Origin and organization 

 of the Expedition to the Black Hills. 



The Black Hills were explored during the summer of 187ft, in accord- 

 ance Avith the instructions of the Secretary of the Interior. Some little 

 confusion has arisen in regard to their identity, for the reason that the 

 mountains adjoining Laramie Peak, in the southeastern part of the Terri- 

 tory of "Wyoming, have been called by the same name. The latter, however, 

 in the recent surveys of that region, have been more properly designated the 

 Laramie Mountains; and as a further guard against confusion, the mount- 

 ains which form the subject of this report are usually called the Black 

 Hills of Dakota. 



The name Black' Hills is said to have been applied to these, the only 

 mountains of Dakota, from the fact that, as they are approached from the 

 barren, desert wastes of the Plains, they loom up in the distance as a dark 

 range, black from the heavy growth of timber they support, They lie 

 between the 43d and 45th parallels of north latitude, and between the 103d 

 and 105th meridians of longitude west from Greenwich, occupying an 

 irregularly shaped area, about 120 miles in length, from north-northwest to 

 south-southeast, and having a width of from 40 to 50 miles. 



The meridian of 27° west from "Washington (approximately 104° west 

 from Greenwich) forms the boundary line between the Territories of Dakota 

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