54 ALASKA GLACIERS 



visible glacier snout and were extended along the floor of 

 the valley beneath the gravel plain, seemed to be shown 

 by other phenomena. First, the water of ablation, though 

 flowing out from the surface of the glacier near each side, 

 did not visibly escape from the ice in the central part, but 

 oozed up through the contiguous gravels, gathering in a 

 number of streams, which attained their full size about a 

 quarter of a mile from the ice front. Second, the gravel 

 plain in the vicinity of the ice front was dotted by numer- 

 ous pits, the larger of which contained lakelets. The 

 sides of these pits were steep and exhibited the stratifi- 

 cation of the gravel in section, the pits having evidently 

 been formed after the gravel was deposited; and there 

 can be no doubt that they originated from the melting of 

 buried ice and the consequent sapping of the gravel bed. 

 The ice whose melting was thus demonstrated may have 

 been part of a continuous sheet or may have constituted 

 a series of isolated masses, but in either case each local 

 mass must have reached its position as part of the glacier. 

 The history seems to be, that the waning glacier was so 

 reduced by the wasting of its surface near its end that the 

 debris of its moraines, worked over by glacial streams, 

 overspread the ice and buried a wide belt. At the time 

 of my visit this was gradually and irregularly melting, 

 under the influence of underground waters, and by its 

 melting was sapping the gravel plain. 



This process is of interest to students of Pleistocene 

 glaciology, because it is evident that with a slight change 

 of conditions it might lead to the formation of familiar 

 features of the < modified drift.' If the locality lay some- 

 what higher above tide, and if the glacier were so situ- 

 ated that, with the progress of its melting, the water of 

 ablation would be drawn off in some other direction, the 

 gravel plain would be left intact except for such changes 

 as resulted from the melting of the ice beneath it. Where 



