382 ON THE NATUEE AND ORIGIN OF 



by tributary eskers. The branch eskers of Nova Scotia 

 with one exception, are parallel, re-uniting at a short distance. 

 This exception divides going down a slope. The usually 

 stratified condition of these eskers show the action of running 

 water, but to what extent their formation is due to this 

 remains to be investigated, but we know that the presence 

 in the eskers of Nova Scotia of fine sand and sometimes 

 clay shows usual deposition by a moderate current. 



Course of Transportation. — Tranverse eskers do not 

 always contain the same constituents as the surrounding till 

 or modified drift. This is an important point, as it gives us 

 valuable information as to the source of the material of the 

 eskers. However, like many other points, it needs investi- 

 gation to decide whether this material came along the course 

 of the so-called esker stream, down the drainage system, or 

 directly along the course of ice movement. 



Eskers, as a rule, contain little clay, indicating a leakage 

 of the fine material, even on the lowlands. 



Chamberlain and Salisbury say that esker stratification 

 is often much distorted, probably on account of ice pressure. 

 Ice pressure could not possibly exist in a subglacial stream 

 which was continually eroding its channel with an extremely 

 rapid current heavily loaded with coarse sediment. These 

 varied opinions show the need of further investigation. 



Fatal Objections. — Another and more fatal objection to 

 the subglacial origin of eskers is the following: We have 

 been considering the subglacial stream as fully formed, and 

 in continual operations as a huge siphon, but there was a 

 time when there was no subglacial channel and the whole 

 eastern part of the continent to the latitude of New York 

 was wrapped in a mantle of ice. When we think of the first 

 few drops of water trickling through the first tiny crack, 

 or leaking beneath the ice, by what vagary of natural law 

 can we conceive it defying the force of gravity and forcing 

 a passage up hills 400 feet high and down across well-marked 



