194 REMARKS ON SANDSTONE AND 



ridges of coarse friable sandstone occur. These hills, though 

 irregular in direction, appear to range from north to so ith. 

 They may perhaps be a continuation from the Cotes N'oires, 

 or Black Hills, which are situated farther to the north, and 

 are said to contain the sources of the Shian, the Little Mis- 

 souri, and some branches of the Yellowstone. Lewis and 

 Clark's Hist. Vol. I. p. 183. The strata which compose 

 these hills are not inclined, and their appearance indicates 

 recent marine origin. The only rock wliich I have met 

 with here is sandstone, of a kind not unlike that wliich usu- 

 ally accompanies coal. This inconsiderable tract being 

 passed, the surface again sul)sides to a plain ; but is more 

 barren and gravelly than before. Instead of tlie tine and 

 somewhat fertile sand which prevails to the east of the above 

 mentioned ridge, the surface is here almost entirely made 

 up of small pebbles and gravel. The soil is of course bar- 

 ren. 



From this plain the Rocky Mountains are first seen at a 

 distance, in some states of the atmosphere, exceeding one 

 hundred miles. They first discover themselves, not by 

 emerging from below the sensible horizon, but become dis- 

 tinguishable from the clouds and the sky above it. Their 

 snowy and shining summits, when first seen, were mistaken 

 for clouds by almost every individual of our party. On ap- 

 proaching such considerable elevations, it is not uncommon 

 to look for great changes in the structure and materials of 

 the surface. But here none such are seen until you arrive 

 at the very foot of the mountain. Where the Platte first en- 

 ters the plains, the horizontal strata of sandstone exten;! to 

 within five miles of the commencement of the high granitic 

 ridge which forms the first barrier of the Rocky Mountains. 

 On the Cannon-ball River, eight miles above its confluence 

 with the Platte, and less than one-thir d of that distance from 

 the granitic ridge just mentioned, are several ranges of small 

 hills ruiuiing parallel to the general direction of the moun- 

 tain, and extending to the northward for a considerable dis- 



