eskers in the vicinity of rochester, new york. 203 



Testimony of Existing Glaciers. 



Existing glaciers do not throw a great deal of light on the 

 problem of esker origin. The remoteness of continental ice masses 

 and the paucity of observations on them have been unfavorable 

 factors in this connection. The continent of Antarctica is covered 

 by a continental glacier that approaches most nearly the great con- 

 tinental ice sheets of past time. Unfortunately it is not well known, 

 and furthermore it does not furnish the requisite conditions neces- 

 sary for the study of esker formation, its edge being nearly every- 

 where buried beneath sea waters. 



Chamberlin has made a study of the Greenland glacier (9). He 

 states that the drainage was largely confined to streams running 

 along the sides of the glacial lobes, sometimes tunneling under the 

 ice, or buried beneath snow drifts. On the disappearance of the 

 snow and ice, deposits in such streams will resemble the terraces and 

 eskers of our drift, but nothing typical in the way of esker forma- 

 tion was noted. However, it was observed, and this has repeatedly 

 been confirmed, that the debris of the ice was confined to its lowest 

 portion, with few exceptions at heights not greater than the heights 

 of kames and eskers, a fact directly antagonistic to the superglacial 

 method of esker origin, as already pointed out. 



Hoist found on the ice in south Greenland a stream 5 feet wide 

 and 5 feet deep flowing on the surface for some distance, separating 

 into two branches in one place enclosing an island of ice, before 

 plunging into a moulin (66). 



A. Kornerup in the published report of his travels, 1879. pub- 

 lished 1881, states that he found in the Ausalik valley of Holstein- 

 borg, "a. typical gravel-ose about 4 miles long, parallel to the present 

 direction of the motion of the inland ice, and having a roof-shaped 

 top, and even sides, inclined 20° to 25° to the plane of the valley 

 over which it extended in a meandering course." Further he states 

 that the valley is "an unusually large plain, bounded by even, gently- 

 sloping foot hills." 



Alpine glaciers afi^ord evidence of little significance in this con- 

 nection. Their high gradients and paucity of materials are not favor- 

 able for the development of eskers. Materials are insufficient in 

 amount to clog the subglacial channels at their lower ends thus lead- 



