EXDLICH.] DRIFT. ^ 89 



debris from the slopes could accumulate and form drift. In the cauon 

 above named, however, erosion and weathering has loosened many 

 bowlders and fragments on the fices of the walls, and they have fallen 

 downj forming a sort of talus at the bases of the cliffs. Continuing dis- 

 integration would soon reduce them to sand and silt, and their removal 

 would follow were it not for the fact that constantly reinforcements ar- 

 rive from the same source, which enable the talus to retain its character 

 of avalanchial dritt. A.long the bases of high Green River cliffs ii 

 similar drift may be observed, but its rapid weathering soon destroys it 

 altogether. 



River-drifts, consisting of the water-worn bowlders, and sand-bars, 

 we have both in the Grand and in the White. While the latter more fre- 

 quently contains smaller pebbles and much sand (so far as flowing in 

 the western portion of the district is concerned), the Grand carries large 

 bowlders. Of the White the same can be said for the vicinity of the 

 agency. When it reaches that point, it has just passed through meta- 

 morphic, palaeozoic, and partly mesozoic rocks, and carries with it the 

 proofs of its course. In some of the broader valleys bordering on the 

 White, we find that this drift has been more or less distributed. This is 

 due to the river's gradually shifting parallel to its own course. The drift 

 carried and deposited by the streams flowing both into White and 

 Grand partakes greatly of the character of alluvial soil. It is muiuly 

 "a fine-grained soil, containing more or less sand, either uniformly dis- 

 tributed or in single layers and banks. In the valleys of the White 

 River drainage the accumulation of this material is simply enormous. 

 It traverses the valleys from one side to the other, and is sometimes 40 

 to 60 feet in thickness. Deep gullies are cut into it by every stream 

 coming from either side, a fact which makes travelling very slow. Wher- 

 ever Indian trails are found they lead over more easily-crossed ravines. 

 The Indians have recognized the dif&culty of travelling over so broken 

 a country also, and their trails, therefore, are found on ridges c nd on the 

 on the divides between main streams. 



It is owing mainly to the lithological character of the surrounding 

 rocks that the drift is formed in such enormous masses. All of them 

 disintegrate quite readily, and because of their " tough " character do 

 not so soon lose the argillaceous portions, otherwise we would find but 

 accumulations of sand. Sandstones, shales, and marls, all of these are 

 rapidly eroded, rapidly yield to atmospheric influences, and are easily 

 transported. During the rainy season the creeks and streams, that later 

 are perfectly dry, carry large quantities of water, and carry with them 

 tons of the drift-material. This is deposited in part as soon as the rapid- 

 ity of the flowing stream is diminished, and in the course of time forms 

 the enormous banks that we observed along the streams. Even in the 

 dry season the White is constantly muddy, owing to the character of the 

 strata through which it and its tributaries find their way. Should water 

 ever be sufficiently plentiful in these localities, the drift just mentioned 

 will furnish excellent arable land. It will naturally be liable to encroach- 

 ments from the main stream, but arrangements could be made to avoid 

 any serious damage. The question of an adequate supply of water for 

 agricultural purposes along the main tributaries of the White is one, 

 however, that can probably, even now, be answered nagativ'ely. 



For the white settler, the region surveyed during 1876 offers but lim- 

 ited inducements. The quantity of water, above all things, is too small 

 to permit of any even approximately dense population, because most 

 likely the country could not sustain it. Good, large timber is rare in 

 the low lands, and the higher regions are too distant to admit of trans- 

 portation, even could it there be found in satisfactory quantities. 



