162 
ALASKA GLACIERS 
several extensive banks of waterlaid material constitute 
terraces, both on the mainland and on the shore of Van¬ 
couver Island. These banks are flat-topped, and esti¬ 
mated to rise from ioo to 200 feet above the water. One 
of them was seen to overlap hills with distinctly glacial 
sculpture, and as they are from 50 to 100 miles within 
the limit of the glaciated district they must have been 
accumulated after the last ice maximum. 
The glacial deposits we encountered are of trivial mag¬ 
nitude collectively, in comparison with the glacial erosion 
of which we saw evidence, and it was therefore inferred 
that the principal regions of glacial deposition lay outside 
the field of our observation. This inference agrees with 
the conclusion of Dawson that the ice-sheet embraced the 
entire Alexander Archipelago, together with all other is¬ 
lands of the coast except the Queen Charlotte, and that its 
outer margin was beyond the present line of coasts. 
Associated Sea-Levels . — The question of the relations 
of sea and land at the time of the great Pleistocene glacia¬ 
tion is of much interest, and some considerations bearing on 
the question will be mentioned, although the evidence at 
present available is either indirect or negative. As gla¬ 
ciers are chiefly phenomena of the land, and as glacial 
erosion in this district has been carried far below the 
present sea-level, it is natural to assume that the sea- 
level associated with that erosion was much lower. A 
little consideration, however, will show that such a con¬ 
clusion does not necessarily follow. The deepest known 
hollow ascribable to ice work is in Chatham Strait, and 
lies 2,900 feet below sea-level. At that point the total 
depth of the great glacier was probably 6,000 feet. It is 
commonly assumed that where a glacier enters a sea not 
deep enough to float it, a part of the ice, equal in weight to 
the displaced water, is upheld by the water, and the pres¬ 
sure of the glacier on its bed is correspondingly dimin- 
