74 ALASKA GLACIERS 



that the water controlled the form of the ice front to only 

 a moderate extent. The principal island of the group, to 

 which we gave the name Heather, is nearly three miles 

 long and has an irregular surface, rising at one point to a 

 height of 500 feet. It consists chiefly of rock. Several 

 lower islands lie north of it, and the ice front rested 

 against one of these for a space of 3,000 feet. The number 

 of islands varies with the state of the tide, and it is pos- 

 sible that all are united at lowest tide. 



Opposite the great nunatak were two medial moraines, 

 one passing within a half mile of its base, the other lying 

 about one mile from the opposite edge of the glacier. A 

 central tract two miles broad was practically drift-free. 

 Toward the end of the glacier this central tract broadened, 

 the medials swinging toward the sides, until finally the 

 white belt was three miles wide. As the medials diverged 

 they also broadened, and they eventually merged with 

 flanking moraines, so that near the end, especially on the 

 east side, the areas of drift-covered ice were very wide. 

 The marginal belt on the west, instead of continuing north- 

 ward parallel to the medial with which it was associated, 

 was seen to curve about into the western embayment, as 

 indicated on the map, and a belt seen from a distance near 

 the north edge of the embayment was supposed to be its 

 continuation, a loop being made within the embayment. 

 As the ice in the embayment descended toward the west, 

 it is evident that the morainic loop could not at that time 

 represent a line of continuous flow, for we can not suppose 

 the ice to flow into the embayment on a descending course 

 and then return on a parallel ascending course. It is 

 therefore probable that the moraine was formed as a com- 

 paratively direct line of drift, following the course of 

 the main ice current at a time when no current entered 

 the embayment. The inference that a change has oc- 

 curred naturally leads to enquiry as to the precise nature 



