Geological Papers. 95 



the ice and to what extent they were deposited at the distance 

 of one, two or three miles from the precise edge of the glacier. 

 These ridges are from one to a few miles wide, are composed 

 essentially of till, and possess, in the main, a gently flowing 

 contour which distinguishes them from the rougher ridgings 

 and sharper contours of frontal moraines. 



Lodge Moraines. — These moraines are found just under 

 the thin border of the ice-sheet ; and constitute a submarginal 

 accumulation. 



ENGLACIAL DRIFT. 



This drift was borne within the ice-sheet itself, but at the 

 melting of the ice it was so mixed with the superglacial ma- 

 terial that it is difficult to separate the two. 



ENGLACIAL STREAMS. 



An englacial stream is a stream which flows within the 

 glacier itself, a stream inclosed within the ice. The work that 

 they may have performed in glacial times is as follows : (a) 

 They may have amassed glacial sediment directly from the ice 

 by melting the ice around the debris and transporting it. (b) 

 They were often conduits for streams, otherwise subglacial, 

 their mission being simply to protect the ground-moraine from 

 erosion. Moreover, in them glacial gravels may have been de- 

 posited, in which case the stratification of the sediments was 

 generally obliterated by the melting of the subadjacent ice. 



SUPERGLACIAL DRIFT. 



This drift was borne on the ice or at its margin. It was 

 collected from the cliffs and towering peaks in the vicinity 

 of the ice-sheet or was carried into it by superglacial streams. 

 It may be classified as follows : 



Dump-Moraines. — These are a variety of terminal mo- 

 raines. They are formed from material borne on the ice-sheet 

 (or within it) which is dropped at the terminus of the ice. 

 This, when the ice remains stationary for a sufficient period, 

 grows into a bordering ridge. 



Push-Moraines. — These are formed by the mechanical 

 thrust of the ice when it advances against any incoherent ma- 

 terial that lies in its path. 



Upper Till. — This till is formed both by englacial and 

 superglacial action. It is material let down over the whole 

 territory of the ice-field, either during its successive stages 

 of retreat or by being let down directly through the melting 



