634 ALLEN DAVID HOLE 
rare, shale exposures abundant, and topography due to landsliding 
often clearly evident. 
The maximum thickness of ice in this valley was probably not 
more than 200 to 300 feet. 
VALLEY OF THE EAST DOLORES RIVER 
Glacial ice descended the valley of East Dolores River to an 
elevation of 9,550 feet. Ice was continuous from this point up the 
north branch over Lizard Head Pass, up the main valley to the 
cirques south of Sheep Mountain, and to the top of Flat Top 
Mountain. Southwestward from Lizard Head Pass, two lacustrine 
flats mark the position of silted-up lakes. Over most of the 
remaining surface up to 100 or 200 feet above the stream, glacial 
drift is abundant. At no point in the Telluride quadrangle was 
drift found containing a larger proportion of striated bowlders than 
along the north side of this valley below Lizard Head Pass. The 
topography on the south side of the stream is more uneven than on 
the north, but a forest growth has made the determination of the 
composition of the surface deposits more difficult. The 10,200-foot 
hill lying in the valley a mile and a half below the pass has a core 
of igneous rock overlaid by drift. At the point where the stream 
changes its course to nearly due south, rock in place is exposed on 
the west side of the stream and drift is not abundant. On the east 
side, however, morainal hills continue to the junction of the two 
branches of the stream. 
The upper boundary of the glaciated area on Flat Top Mountain 
is a 25° to 30 slope of bare shale 40 to 50 feet high, extending in an 
east-west direction for about half a mile. This steep, northward- 
facing slope lies a little south of the southern boundary of the 
Telluride quadrangle. From 11,800 to 10,500 feet in elevation 
roches moutonnées are abundant, and in many places show striae 
bearing northeast of north, in general parallel to the course of the 
stream. To the northeast, the northwest, and the west, lobes of 
ice extended to the edge of the steep, precipitous slopes of igneous 
rock. Along the valley to the northwest, down to about 11,000 
feet in elevation, roches moutonnées and striae are abundant. The 
valley leading northward to the Dolores River is a broad ravine in 
