GLACIATION IN THE TELLURIDE QUADRANGLE 609 
in their bottoms, and both have steep descents to the valley below. 
There is much talus at the bases of the surrounding slopes. 
VALLEY OF LAKE FORK 
The term Lake Fork is sometimes used to designate that part of 
the tributary of the San Miguel River from the south which lies 
above the point of junction with Howard Fork; while that part 
from the mouth of Howard Fork to the San Miguel River is called 
South Fork. In this paper, however, the terms lower valley of 
Lake Fork, and upper valley of Lake Fork, are used to designate, 
respectively, the portion below and the portion above the mouth of 
Howard Fork. 
LOWER VALLEY OF LAKE FORK 
Glacial ice coming down Lake Fork to the valley of the San 
Miguel not only filled the lower valley of Lake Fork, but spread 
eastward over the edge of the mesa to a distance of a mile or more 
from the stream, and together with the glacier in the valley of Bilk 
Creek entirely covered the mesa between Lake Fork and Bilk Creek 
for a distance of more than three and one-half miles from the San 
Miguel River. 
The surface of the glacial drift on this mesa is highest toward 
the northern end, being at a maximum more than 200 feet higher 
than the outcropping bed rock at the mesa’s edge; the surface is 
lowest just west of the mouth of Turkey Creek, where the drift 
forms but a thin covering. The ice from Lake Fork passed over the 
mesa at this point into the valley of Bilk Creek, as is shown by 
glacial striae on bed rock at the west edge of the mesa, bearing N. 
17, W. to N. 24° W. Striae on bed rock at the east edge of the 
mesa, opposite the mouth of Turkey Creek, vary in direction from 
N. 3° W. to N. 16° E., the direction of a considerable number being, 
therefore, approximately parallel to the course of Lake Fork. 
The drift on the mesa between Lake Fork and Bilk Creek is 
arranged in the form of ridges. The highest part of the deposit 
consists of a ridge about half a mile in length, extending in an 
approximately north-south direction with a very steep western 
slope. Southward from this, the ridges have a general northeast- 
southwest trend, changing at the northeast end to a more northerly 
