716 ALLEN DAVID HOLE 
ALONG THE STREAM SOUTHWEST FROM BLACK FACE MOUNTAIN 
In the valley of the small stream heading at 10,600 feet elevation 
west of south of Black Face Mountain, glacial drift is exposed at 
intervals up to 10,700 feet. Clearly striated bowlders occur at 
10,400 feet; at 10,500 feet bowlders in variety include Potosi 
rhyolite, the largest about 20 feet in diameter. Above 10,700 feet 
no glacial drift or other signs of glaciation are found. 
This deposit is classed as earlier drift partly because of its 
composition, including large Potosi rhyolite bowlders, but chiefly 
because of the lack of evidence of glaciation in the upper part of 
the valley. 
NORTH SIDE OF EAST DOLORES RIVER 
North of the terminal portion of the glaciated tract in the valley 
of the East Dolores, rounded and subangular bowlders in variety 
occur at intervals up to elevation about 10,100 feet, that is, to a 
height of 400 feet above the upper limit of drift of the more recent 
epoch. The varieties most frequently found are diorite-monzonite 
and Telluride, with fragments of sandstone which is here the under- 
lying formation. No good exposures or sections occur in this area, 
and no striated bowlders were found. The deposit is classed as 
drift because of its composition and its abundance. It is classed 
as older drift because of its topographic position and considerably 
weathered surface. 
EAST SIDE OF EAST DOLORES RIVER 
On the east side of the East Dolores River, above the mouth of 
the branch heading at Lizard Head Pass, a belt about three-eighths 
of a mile wide above the upper limit of glaciation as mapped for the 
more recent epoch contains occasional deposits of bowlders in 
variety, and an irregular topography including at the southern end 
of the belt some undrained depressions. The irregularity of the 
topography is, in part, clearly due to landsliding, but striated 
bowlders found in some parts of the area are evidence that the 
surface deposits include glacial material. As has already been 
stated, this belt is classed as older drift because of its topographic 
position, high up on the slope, and because of the relative scarcity 
of the drift in this belt as compared with the deposits of the more 
recent epoch near the stream. a 
