IOO 



ALASKA GLACIERS 



are steeper than those toward the north. Close to the ice 

 front the plain was interrupted by a low ridge of gravel 

 (see fig. 54), a push-moraine associated with some small 



FIG. 54. SOUTH WALL OF VALLEY AT FRONT OF GREWINGK GLACIER. 



and recent advance of the glacier, and possibly a phenom- 

 enon of the annual oscillation of the front. Farther out 

 on the plain the course of a much larger moraine was 

 marked by a crescentic line of mounds and short ridges, 

 remnants of a once continuous morainic rampart that had 

 been breached at many points by streams from the gla- 

 ciers. I judged that this also was a pushed-up ridge, 

 resulting from a plowing of the gravel deposit during a 

 rapid advance of the glacier. It was not strictly parallel 

 to the ice front in 1899, nor to its outline as mapped in 

 1880, but was more convex downstream. Its middle 

 part was 2,600 feet from the glacier in 1899, and its most 

 southerly remnant 800 feet. In 1880 Dall observed a 

 considerable amount of ice under the sand and gravel of 

 these mounds, and I noted many kettle-holes resulting 

 from recent melting of ice remnants under the gravel 



