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Eskers. — In regard to the much-vexed question of the origin of 

 those extraordinary chains and strings of sand-and-gravel mounds 

 called Eskers, I am still, as I was in 1874, inclined to regard these 

 also as only another form of sedimentary deposit left by the melting 

 ice. I believe that their position in the first instance was deter- 

 mined by the mounds they stand upon having been high enough 

 above the stronger currents of the subglacial streams to allow of 

 the accumulation of sand and gravel resulting from the washing of 

 the Till higher up the valley. This was occasionally added to, 

 perhaps, by material washed down through moulins and crevasses. 

 When once such a mound was started, the action I have above 

 described would tend to perpetuate its form as it increased in size. 

 It would be precisely at the spots where such subglacial mounds 

 occurred that, as the ice became weaker and thinner under atmos- 

 pheric and other waste, crevasses and their accompanying moulins 

 would be more readily developed, and, consequently, where the 

 water of the superglacial streams would sweep down in greatest 

 quantities the boulders, gravel, and sand that were being liberated 

 at the surface. And as this process would, by my theory, go on 

 until the continuity of the ice sheet was destroyed by melting, 

 there would certainly be formed, as the last traces of the ice sheet 

 vanished, long chains of steep-sided hummocky mounds enclosing 

 land-locked hollows, just as we find them in esker regions. 



Relations of Eskers and Moraines. — I am inclined to regard 

 some of the esker-like mounds occurring in places as having origin- 

 ated in much the same way as a moraine. But as a rule, they are 

 not terminal moraines. I for one do not believe that such a thing 

 as the terminal moraine of the great ice-sheet can anywhere be 

 seen. Here and there, where the ice-sheet was melting over a 

 great ridge, or along a great hill side, quantities of materials liber- 

 ated by the melting of the upper parts of the ice, and set free on 

 its surface, were washed off that surface on to the land exposed by 

 the withdrawal of the ice. And in this way esker-like, or moraine- 

 like, mounds would be produced. But in no sense can they be 

 regarded as terminal moraines. Such mounds occur here and 



