G/. .1(7.1/. GF.OLOGY OF XORTII GREENL.IND 



799 



The juxtriposition of the highly inclined and approximately 

 horizontal layers, as shown in the figure, is explained as follows: 

 In recent years the snow fall has exceeded the melting. Of this 

 there was abundant evidence. Just before this condition of 



¥]G. 28. Diagram showing longitudinal section of ice, as shown in the wall of 

 the canyon of a superficial stream where the latter crossed a surface moraine. 



things came about, meltintr had exceeded accumulation. The 

 surface of the ice had been lowered, but the drift had protected 

 the ice immediately beneath it, so as to give origin to a low ice 

 ridge beneath the drift along the line of debris. It is believed 

 that, at this stage, all the layers of ice near the edge of the ice- 

 sheet were upturned, as they are now believed to be a little 

 below the surface. The theoretical condition of things before 

 the heavy snows of recent years is illustrated by Fig. 29. 

 Later, when the snow fall exceeded the melting, the falling and 

 accumulating snow was transformed into horizontal, or nearly 

 horizontal, layers of ice (or neve), where it rested on ice. The 

 drift, because of its heat absorbing qualities, helped to melt the 

 snow which fell upon it, and its surface being elevated above that 

 on either hand, allowed the snow to be blown off more than 

 from the surroundinsf surface. 



P"iG. 29. Hypothetical profile of surface of Fig. 28 before the development of 

 the overlving horizontal layers. 



The drift phenomena shown on the edge of the ice-cap in 

 association with the upturned layers, was repeated in many cases 

 on glaciers, on the surfaces of which the upturning layers of ice 

 had given origin to irregular and discontinuous ridges of drift. 



