ROCK GLACIERS IN ALASKA 



371 



fact in mind. McConnell and Brock/ on the other hand, in their 

 report on the Frank landslide, fail to report any systematic ridgings like 

 those at Elm, or in the rock streams of the San Juan Mountains.^ 



Perhaps the most indicative facts which lead us to conclude that 

 the rock glaciers of the Nizina region are now in motion, moving in 

 some such way as a glacier, are : 



EiaailJcSHEs 



Fig. 7. — The upper end of a rock glacier, showing the cirque-like character of the 

 valley head, and the origin of the longitudinal ridges in the talus slopes of the head 

 walls. 



1. The remarkable resemblance in position and form to present 

 live glaciers in the immediate vicinity. 



2. The direct connection and perfect gradation between present 

 glaciers above and long rock glaciers below. 



3. The presence of interstitial ice at no great depth below the sur- 

 face in all of the rock glaciers which were dug into. 



1 R. G. McConnell and R. W. Brock, "Report on the Great Landslide at Frank, 

 Alta., 1903," Ann. Rept., Dept. Interior, Canada, 1903, pt. 8. 



2 Ernest Howe, op. cit. 



