GLACIATION IN THE TELLURIDE QUADRANGLE 725 
part of the last, feeble, intermittent struggles of the glacial forces 
which earlier in the epoch acted with such vigor in the same region. 
SUMMARY AND CONCLUSIONS 
TOPOGRAPHIC EFFECTS OF GLACIATION 
1. Cirques.—Almost all valleys in the quadrangle which have as 
much as half a mile of their course above 11,000 feet in elevation 
were occupied by glaciers in the more recent epoch; at the heads of 
many of these valleys cirques were developed. A typical cirque 
may be considered as having (1) a nearly perpendicular bounding 
wall, semicircular in plan, and (2) a comparatively level bottom. 
In a few places this typical plan is closely approximated; in most 
cases, however, there is variation in many ways. The bounding 
wall may be only a small arc of a circle, making the resulting cirque 
a broadly open one; or the nearly perpendicular faces of rock may 
be prolonged on each side of the valley for a mile or more in the 
downstream direction, producing a deeply recessed valley head 
which approximates the linear form characteristic of valleys. The 
slope of the bounding wall as a rule approaches perpendicularity 
only at some distance above its base—usually not more than the 
upper one-half of the vertical height of the wall shows the steep 
faces left by falling blocks or fragments (Fig. 9); at the base in 
almost all cases are slopes of waste, generally in the form of bare 
rock fragments, but occasionally so far weathered as to furnish a 
soil where an Alpine flora can gain sufficient foothold to cover the 
surface in the summer months with a carpet of green. The bottoms 
of the cirques also present variations. In some cases much of the 
floor‘is rock in place, frequently grooved and striated, and contain- 
ing depressions in its surface in which are shallow lakes varying in 
size up to one-fourth of a mile or more in diameter. In other cases 
the floor is covered in whole or in great part with rock fragments 
and soil; the bottoms of such cirques are as a rule more irregular 
and less nearly horizontal than in the case of the cirques which 
contain lakes. Rock streams, already described, are found only in 
cirques or in the upper parts of valleys at a corresponding elevation. 
2. Hanging valleys—Numerous hanging valleys occur in the 
quadrangle; in most cases they were themselves occupied by 
