204 ROCHESTER ACADEMY OF SCIENCE. 



ing to aggradation. Furthermore the high gradient of the valleys 

 cause such rapid flow that only small deposition occurs, the outwasli 

 being carried on down the valley. 



A deposit of the nature of an esker is described as occurring on 

 a small glacier on Mt. St. Helena, Washington. "It was perfectly 

 straight and regular in form, about 300 feet long, 20 feet wide at the 

 base, 5 feet high and with a slightly convex crown of about 4 feet." 

 Its materials were like those of the moraines associated with the 

 glacier, "but worn, rounded and all of much smaller and more uni- 

 form size." At the foot of the side slopes the demarcation was clear 

 and well defined, at its upper end it terminated against a lateral 

 moraine into which it appeared to grade. Its lower end was abrupt, 

 with no gradation and no dump. Russell suggests that it appears 

 to have been formed in a tunnel by an englacial stream and after- 

 wards brought to the surface by the melting of the ice OT). Tarr 

 and Martin as a result of their Alaskan studies in the Yakutat Bay 

 region state that eskers are subglacial deposits mainly, if not entirely, 

 associated with stagnant ice conditions. However, in the bases of 

 stagnant moraine-covered glaciers of this region, no eskers were 

 observed in the process of formation on account of the dearth of 

 streams. Some eskers buried by outwash were observed (106). 

 Tarr has noted small eskers in Alaska on ground from which the 

 glaciers have receded within a century (105). 



Russell's study of the Malaspina glacier constitutes a classic in 

 geology (80, 81. 82, 83). He states that the drainage of the Malas- 

 pina glacier is almost entirely interglacial or subglacial. There is no 

 surface drainage except very locally, here the streams are short and 

 soon plunge into a crevasse or moulin. On the Alpine glaciers trib- 

 utary to the Alalaspina there are a few short streams confined to 

 their lower portions, but they soon disappear from view. 



He further states that the lakes on the moraine-covered portion 

 of the glacier "last from year to year," but are finally drained, 

 usually through a crevasse or opening of some sort at the bottom, 

 and the basins are left with a deep filling of l)oulders and stones. 

 They protect the ice beneath from melting and eventually come to 

 stand out on pedestals as a result of the ablation of the surrounding 

 surface (83). 



