GLACIAL GEOLOGY OF XORTH GREEXLAXD 805 



qucntl\-, the leaves and twigs of the little shrubs which grow on 

 the land in the vicinit}'. 



The general absence of superglacial material on the ice-caps 

 and glaciers of Greenland, except in situations in which debris 

 has always been known to occur on glaciers, would seem to put 

 an end to the doctrine which has been given currency in certain 

 quarters that glacial debris in large c^uantities rises through the 

 ice and gets upon its surface ; for if the ice-cap of Greenland 

 is free from superficial debris — except at its very margin — it 

 would seem that the same should be still more conspicuously 

 true of an ice-sheet on a plainer country, like our own. It is 

 believed, however, that the phenomenon of the upturning of the 

 layers of the ice at the edge of an ice-sheet would hold in a flat 

 region, as well as in a mountainous one, especially where the ice 

 was well charged with debris in its lower parts, and that this 

 upturning would give rise to superficial drift for a few yards, or 

 possibly a few hundred yards, back from the edge of the ice. 



The disappearance of the doctrine of superglacial drift, as a 

 general phenomenon, carries with it, of necessit}-, the doctrine 

 that kames and eskers are the product of superglacial waters. 

 On this point it should be further said that hundreds of super- 

 glacial streams, long and short, were seen on the ice-cap and on 

 the glaciers of North Greenland, and with a single exception 

 there was no material whatsoever accumulating in their chan- 

 nels. Except within the limits noted there was no drift upon 

 the ice which the surface streams could not get hold of, nor, except 

 at its very margins, was there drift in the ice dowm to the level 

 to which the streams cut. Furthermore, the streams are almost 

 uniformly so swift that no drift could accumulate in their chan- 

 nels unless it w^ere extremely abundant on the surface. Every 

 considerable stream seen on the ice had so high a velocity, and 

 so smooth a bed, that e\'en bowlders of considerable size would 

 have been hurried along it precipitately, had they once entered 

 the channel. 



In the single case in which debris was seen in a superglacial 

 stream channel, the amount was small and the conditions pecul- 



