426 ELIOT BLACKWELDER 
Evidently the lake was formerly covered by a glacial lobe which has 
since collapsed. The extreme recency of the occurrence is indicated 
by the fact that many blocks of ice lie stranded upon the rocky sides 
of the valley 50-100 feet above the water, thus marking the original 
level of the glacier. As such detached fragments usually melt quickly 
in the mild summer months, it can hardly be doubted that the collapse 
took place in 1906. The lowest of these lakes discharges its waters 
into the terminal lake through a cascading brook. ‘The higher lakes, 
however, must have subglacial outlets; much water is poured into 
them by streams from the adjacent slopes, yet there is no exit for this 
upon the surface. It seems probable that the subsidence of the ice in 
the uppermost lake was caused by an unusually rapid removal of 
water through such a subglacial channel. 
The Yakutat Glacier receives no considerable tributaries from the 
mountains on either hand. A few snow-fields and a few diminutive 
glaciers occupy the heads of the gulches on both sides, particularly in 
the valley which contains the shattered ice above mentioned, but these 
do not reach the bottoms of the valleys. 
Of the glaciers between the Yakutat and the delta of the Alsek, 
as well as on the west side of the Yakutat Glacier itself, I can give only 
brief mention. Our route lay too far from the mountains to permit 
us to see them in detail. The Chamberlin, Rodman, and Fassett 
are all large alpine glaciers, and all extend out upon the edge of the 
foreland. On previous maps they are represented as being lobes of 
the inner ice-plateau, but the view from the foreland gave no con- 
firmation of this. Although the upper reaches of the glaciers are 
hidden by the turnings of their canyons, and thus it is not possible to 
see directly whether they come through the rock divide, it is significant 
that they have steep descents, which are much more characteristic of 
the isolated valley glaciers than of the large “‘through”’ lobes. 
Two smaller glaciers lie east of the Fassett. One, the Martin? 
Glacier, is a rather narrow tongue like the Miller and descends 
nearly to the level of the plain. Its companion on the east is of 
similar size, but does not descend as low. '. It derives its name from the 
fact that it is sunk deep in a canyon, the walls of which are remarkably 
« After Mr. E. R. Martin, who was in immediate charge of the U. S. Boundary 
Survey Party which surveyed this portion of the range in 1906. 
