Zl^ 



STEPHEN R. CAPPS, JR. 



4. The longitudinal ridges seen at the upper ends of many of the 

 rock glaciers can often be followed directly to an active talus slope 

 (Figs. 3 and 7). 



5. Nowhere have the talus slopes at the heads of the cirques been 

 able to form any considerable accumulations on the surface of the 

 rock glaciers. This seems to be very strong evidence that the talus 



Fig. 8. — A small rock glacier north of Sourdough Peak, 

 lower face of these features is well shown. 



The characteristic steep 



has moved on down the valley as fast as it has been supplied (Figs, 3 

 and 7). 



6. In all of the best examples of rock glaciers there is a steep slope 

 at the lower end where the gently sloping surface of the upper portion 

 breaks down at the edge at an angle as steep as the talus will lie. Over 

 this steep face the rock fragments are fresh, while the talus on the 

 surface above this slope is usually lichen covered. This seems to 

 show that the material is moving forward fast enough to prevent ero- 

 sion of the lower end from reducing it to a low, graded slope (Fig. 8). 



