194 ROCHESTER ACADEMY OF SCIENCE. 



(3) Glacial debris is almost entirely confined to the base of 

 the ice. Little of it is englacial or superglacial. By far the greater 

 amount of material is located within 50 feet of the base of the ice 

 (9). This would leave little accessible to superglacial streams. 



(4) Existing glaciers show that the drainage of ice sheets is 

 almost entirely subglacial, streams flow but a short distance on the 

 surface before they plunge into a crevasse or moulin. The presence 

 of pot holes in glaciated regions shows that moulins were as char- 

 acteristic of former ice sheets as present ones. 



(5) The rapidity of currents of superglacial streams and the 

 smoothness of their channels are directly opposed to the lodgment of 

 materials in them. 



(6) The materials of eskers are essentially local in character. 

 Davis has shown that the materials of the Newtonville and Auburn- 

 dale eskers have only come from two to four miles to the north- 

 ward (27). To oppose this fact it has been suggested that the 

 upturning of the layers of ice as noted in Greenland would bring up 

 basal materials within a short distance of their source, however, 

 this upturning of ice layers is merely a terminal phenomena and 

 cannot find application here. Further this material would have to 

 rise to a height of 50 to 100 feet in the case of high eskers. too great 

 a rise especially on level ground. If the ice moved over a sedentary 

 ice cap some of the surface debris at the time of esker formation 

 must have been far traveled material, yet even the large boulders of 

 eskers are local in origin for the most part. 



(7) If eskers are let down from a superglacial position across 

 divides they should show evidences of stretching — relation of chord 

 to the arc — however they do not exhibit evidences of stretching in 

 these situations but exhibit uniform preservation throughout the 

 length of the segment (122). 



(8) Ice is so easily eroded that deposits would not be re- 

 strained to definite narrow channels, especially after the stream had 

 become graded, hence narrow ridges could not be formed with char- 

 acteristic uniform cross-sections. 



(9) Ponds and swamps bordering esker courses point to ice 

 block inclusion and show that the ice lingered there longest. If the 

 esker ridges were superglacial they would tend to slide oft" the sur- 

 faces of these blocks to either side. 



