68 



tains, and soon disappear under the cretaceous, forming a compara- 

 tively narrow belt. The east base of the mountains is from 2,000 to 

 3,000 feet below the western. 



The rocks seem also to dip much more suddenly down on the south 

 than on the north side. The strike of these upheaved strata is in 

 almost every direction corresponding on the exterior nearly with 

 that of the tangent to the outline of the mass, and on the interior 

 being more nearly coincident with the direction of the major axis. 



A result of this formation is that the upturned rocks break ofif 

 abruptly on the side towards the interior of the mass, and leave an 

 open valley in many places between this steep slope and the gentle 

 one which succeeds it as we approach the interior. In these valleys 

 the best roads are found, and one, which nearly encircles the Black 

 Hills, is known among the Indians and traders as the Eace Course or 

 Running road. 



The Inyan Kara Peak is basaltic, and the appearance through a 

 powerful spy-glass of those to the north, known as the "Bear's Lodge" 

 and "Little Missouri Buttes," indicates that they are also of this forma- 

 tion. More recent volcanic action is visible at Bears' Peak, and two 

 circular spaces to the west of this peak, now occupied by muddy lakes, 

 indicate the existence here in former times of volcanic forces. 



The highest mountain masses, such a?; Harney's Peak, on the east 

 side, are all granite, the rocks, as seen at a distance, appearing in the 

 same unmistakable form as those on the Raw Hide and Laramie Peaks, 

 namely, coarse granite or gneiss, standing in layers and slabs, indi- 

 cating a vertical stratification. A full description of these mountains 

 must be left for the final report. They derive their name from being 

 covered with pine, whose dark green gives them a black appearance. 

 In reference to the carboniferous rocks in these mountains, Dr. 

 Hayden says : ' ' The exact positions in the carboniferous system to 

 which the limestones around Fort Laramie and in the Black Hills 

 belong, is not sufficiently clear from the evidence yet obtained. They 

 do not seem to be the equivalents of the beds above described along 

 the Missouri, though they may be. The texture of the rock is quite 

 •ualike any of the limestones of the coal measure with which we are 

 atcxjuainted, and there seems to be an absence of the fossils character- 

 istic of the coal measure limestones on the Missouri, and in north- 

 eastern Kansas. The latest opinion, however, of my associate, Mr. 

 Meek, is that they belong to the true coal measures." 



In these mountain formations, which border the great plains on 

 the west, are to be found beautiful flowing streams, and small rich 

 valleys covered over with fine grass for hay, and susceptible of culti- 

 vation by means of irrigation. Fine timber for fuel and lumber, lime- 

 stone and good stone for building purposes are here abundant. Gold 

 has been found in places in valuable quantities, and without doubt 

 the more common and useful minerals will be discovered when more 

 minute examinations arc made. 



I think it exceedingly desirable that something should be done to 

 encourage settlements in the neighborhood of Fort Laramie. The 

 wealth of that country is not properly valued, and the Indian title not 

 being extinguished there is no opportunity to settle it. Those who 



