LATERAL MORAINES 257 



moraine of the Animas glacier itself. The lateral moraines occur as 

 elongate mounds parallel to the main direction of the valley and rest on 

 the hillsides at elevations from 1,000 to nearly 2,000 feet above the valley 

 near Kockwood, but with gradually lower elevations southward. They 

 seldom rise as much as 50 feet above the surface of the slopes on which 

 they rest. The glacier seems nowhere to have carved benches in the sides 

 of the valley. Two lakes or depressions have been formed, one on each 

 side of the valley, by the damming of gulches by lateral moraines. The 

 rims of these basins are 1,600 or 1,900 feet above the present bed of the 

 river, the highest being on the west side some 2 miles below Eockwood. 



Corresponding lateral moraines occur on the sides of Uncompahgre 

 valley, but they are smaller and less perfect in form than those of the 

 Animas. One, however, is noteworthy, especially from the close associa- 

 tion of its gravels with those of the terminal moraine. It lies on the 

 slopes of Baldy peak, one of a group of hills between the high mountains 

 and the lowlands, and east of the Uncompahgre river. The long ridge 

 extending northwest from its summit is thickly covered with gravels and 

 huge boulders, the greater part of which was derived from the Uncom- 

 pahgre glacier; but numerous boulders of massive latite belonging to the 

 later eruptive rocks of the* region have come from Cow creek, an eastern 

 tributary of the Uncompahgre. It is believed that the drift covering the 

 ridge, as well as that extending northeast nearly to Cow creek, represents 

 a lateral moraine of the Uncompahgre glacier blending with a similar 

 moraine of Cow creek. The small lateral moraines of the Uncompahgre 

 are more common on the west side, that at the mouth of Coal creek being 

 characteristic of a number that occur between Ouray and the terminal 

 moraine. After running parallel to the valley as a low ridge some 1,000 

 feet above the river, the moraine turns just before reaching the south side 

 of Coal creek and descends to the level of the present alluvium of the 

 Uncompahgre. North of Coal creek another moraine occurs at the same 

 high level as the first, and after a short distance it also descends. In ad- 

 dition to the more perfectly preserved lateral moraines, drift is found on 

 all the spurs or valley sides that are not too steep to retain such material. 

 In Dexter creek, a tributary of the Uncompahgre from the east, which 

 does not rise in the high mountains and which did not contain a glacier, 

 stratified gravels and coarse sands occur in patches on the valley sides 

 near the present stream, but at elevations well above those at which they 

 could now be deposited by the stream, even at times of flood. The starti- 

 fied character of the gravels is well shown in cuts along the wagon road. 

 They are believed to have been deposited during the last glacial stage by 



