GEOLOGICAL SURVEY OF THE TERRITORIES. 69 



as it were, by the north and south branches of the Big Cheyenne River, 

 the most important stream in this region. The north branch passes 

 along the i>orthern side of the range, receiving very many of its tribu- 

 taries and most of its waters from it, but takes its rise far to the west- 

 ward of the range, near the sources of Powder Eiver, in the " divide," 

 between the waters of the Yellowstone and those of the Missouri, 



The south fork also rises in the same divide, flowing along the southern 

 base of the range, and also receives numerous tributaries which have 

 their sources in it. These two main branches unite al^out 30 miles east 

 of the Black Hills, forming the Big Cheyenne, which flows into the Mis- 

 souri, about 60 miles above Fort Pierre. The Moreau, Grand, Cannon 

 Ball, and other rivers flowing into the Missouri, north of the Cheyenne 

 and south of the Yellowstone, rise in a high Tertiary divide north of the 

 Black Hills, and are, for the greater part of the season, quite shallow 

 and sometimes nearly dry; but the Little Missouri derives a portion of 

 its waters from the Black Hills through a number of small branches 

 which flow from the northwestern slope. 



We thus see that the Black Hills do not give rise directly to any im- 

 portant stream, if we except the Little Missouri, a few branches of which 

 flow from springs near the base of the hills, but afford a comparatively 

 small supply of water from that source. 



We will now allude for a moment to what we believe to be the econom- 

 ical value of the timber in the Black Hills to the jieople now rapidly 

 settling Dakota Territory. As we have previously remarked in this 

 chapter, these hills occupy an area about 100 miles in length, and about 

 60 in breadth, or about 6,000 square miles. I think it is safe to say that 

 at least one-third of this area, or about 2,000 square miles, is covered 

 with excellent pine timber, or 1,280,000 acres. How is this timber to be 

 made available ? As I have before remarked^ the two forks of the Chey- 

 enne River, as it were, clasp the Black Hills, the two branches ijassing 

 along close to the northern and southern borders of the hills. From 

 four to six months of the year these streams are quite high. The logs 

 could be cut and transported to the sides of these streams during the 

 dry season, and when the streams are high in the spring of the year, 

 they could be taken down into the Missouri River with a good degree 

 of safety and ease ; at least that is my impression. In a report made 

 to Lieutenant G. K. Warren, March 15, 1856, I made use of the follow- 

 ing language in reference to this matter : 



The Black Hills, which appear In the distauce, and derive their name from their dark 

 aud gloomy appearance, contain an inexhaustible quantity of the finest timber, mostly 

 pine, which will doubtless remain undisturbed for many years to come. I will, how- 

 ever, propose a plan for obtaining this timber, and rendering it useful to future set- 

 tlers ; though I do it with some hesitation lest it may seem visionary. The left fork 

 of the Cheyenne passes through the northern portion of the Black Hills, and even 

 there is a considerable stream from 30 to 50 yards wide. In the spring the river is 

 much swollen and the current exceedingly rapid, and the timber, if cut and hauled to 

 the banks of the river, might be floated down into the Missouri with considerable 

 safety and ease. 



At the time the above was written 1 had seen but little of the Black 

 Hills, and nothing was known of the geography of the forks of the 

 Cheyenne. 



The geological structure of the Black Hills may be mentioned briefly 

 in this connection. The nucleus or central portion is composed of red 

 feldspathic granite, with a series of metamorphic slates and schists 

 superimposed, and thence upou each side of the axis of elevation the 

 various fossiliferous formations of this region follow in their order to 

 the summits of the Cretaceous, the whole inclining against the graui- 



