GLACIATION IN THE TELLURIDE QUADRANGLE 629 
Eastward from these moraines for about two miles the ice 
spread in a broad sheet, leaving a hummocky, irregular topography. 
The line of farthest advance of the ice is sinuous, and not marked 
by any prominent ridges transverse to the valleys; kettles are more 
abundant, however, near the margin of the moraine than farther 
back to the south. At different points within the glaciated tract, 
short ridges of glacial débris with steep slopes occur; but the whole 
area is covered with a thick growth of spruce and aspen which not 
only obscures the topography, but often conceals the drift. How- 
ever, the occasional exposures made by wash of streams, or in the 
construction of irrigation ditches, furnish abundant evidence of the 
character of the surface deposits. 
An outwash plain of gravel and bowlders extends for about a 
_ mile below the edge of the glaciated tract on the east side of the 
west branch of the stream, having a thickness of from 20 to 30 feet. 
The cirque lying north of Wilson Peak resembles closely the one 
lying next to the east, already described (p. 619). It is broad, 
shallow, and with unusually high, precipitous walls. As in the 
cirques just to the east, the underlying rock weathers readily, and 
roches moutonnées and exposed striated rock in place do not occur. 
The maximum thickness of the ice was undoubtedly greater in 
the cirque west of Wilson Peak than in the one to the north, and 
may have reached 700 or 800 feet. 
NAVAJO BASIN AND THE TWO VALLEYS NEXT SOUTH 
These three valleys were occupied by glaciers which extended to 
an undetermined distance beyond the limits of the Telluride quad- 
rangle. That part of Navajo basin included in the Telluride 
quadrangle is, with the exception of long slopes of talus, almost 
perfectly cleaned out. Roches moutonnées are abundant in the 
bottom, giving a smooth, regular appearance to the slopes as viewed 
from the upstream side. As in other cirques, when viewed from 
the downstream side, a succession of steep slopes appears with some 
low, rough, precipitous walls. 
The cirque next south of Navajo basin is in all essentials like 
others at equal altitude. The valley is, however, much narrower 
than Navajo basin, and the talus slopes lying at the foot of the high 
