78 



Tongue, and Powder rivers,) above their mouths, have ever been visited 

 by any exploring expedition, except those of trappers and hunters. 



The Big Horn river is by far the most important of those streams, 

 and has been navigated by the traders in skin boats, carrying their 

 peltries, from the point where it debouches from the Big Horn moun- 

 tains to the Yellowstone, a distance of perhaps 150 miles. Above 

 where the stream escapes the mountains it is not navigable for any- 

 thing but the smallest boats, and the gorges by which tlie stream 

 passes the mountain range is impracticable for any kind of land 

 transportation ; a considerable detour being required even for pack 

 animals. The portion navigable will, perhaps, according to the 

 opinion of Colonel Robert Campbell, of St. Louis, furnish a depth of 

 water for Mackinac boats, in high stages, of about ]8 inches, but he 

 thinks the navigation of this stream for ascending boats could not be 

 used to any advantage. An undue importance has been given to the 

 navigability of this stream from the erroneous position of the Yellow- 

 stone, as laid down on nearly all recent maps, except those from this 

 office, as they make its position nearly 100 miles too far south. The 

 manner in which I have been able to correct this is given in my 

 report on the compilation of the general Pacific railroad map. 



Poiuder river. — This stream rises near the southern point of the Big 

 Horn mountains, and flows a little east of north. The route from the 

 Platte to the Yellowstone along the stream is practicable, but as a 

 route \'ov wagons it is difficult, requiring the stream to be frequently 

 crossed, and the banks are very muddy, and the bed is occupied in 

 places by quick sand. 



The Little 31issouri river rises near the North Fork of the Shyenne 

 in longitude 105°. I have seen the country near its source, where it 

 forms the northern part of the upheaved stratified rocks of the Black 

 Hills, and at the mouth where the lignite tertiary exists. Its general 

 direction is northeast, and its course through the main portion must 

 be in this lignite tertiary formation. From the statements of mem- 

 bers of Sir George Gore's party, which travelled up the stream in 

 1856, I infer that the route along or near its valley is practicable for 

 wagons, though difficult. The valley is one of the great buffalo 

 regions. 



The Knife river, Heart river, CMinon Ball river, Grand river, and 

 Moreau river, all rise in the prairie ridge east of the Little Missouri, 

 and they contain but little water in the winter and latter part of sum- 

 mer. I have never seen any of them, except at their mouths, and their 

 lengths on my map indicate their comparative size. 



The Big Shyenne is a most important river, and has its extreme 

 sources west of the Black Plills, which its two main branches enclose. 

 These forks are supplied by numerous streams from the mountains, 

 and they unite in about longitude 102° 20', the river flowing into the 

 Missouri in latitude 44° 48'. In its lower course I am informed there 

 is fertile land on its banks, and there are considerable areas in and 

 around the Black Hills. The Shyenne river can probably be rafted, 

 and the streams that come from the hills could be used to drive the 

 logs down to the river. It must be borne in mind that the pine grow- 

 ing on the Black Hills is difficult of access, and the expense of getting 



