ALASKA GLACIERS 
188 
or varied by traveling dunes of lapilli. To my eye they 
conveyed no impression of ice sculpture; I saw neither 
the long parallel grooves and ridges which glaciers some¬ 
times carve from homogeneous rocks, nor the groups of 
moutonnee bosses which they usually develop where rocks 
are of varied texture. On the main part of the island are 
younger cones with well-preserved craters, and photo¬ 
graphs show that with these are associated crags such as 
an overriding glacier would not spare (fig. 89). Neither 
is it to be supposed that the craters themselves would 
survive the erosive action of a great ice-sheet. It may 
be affirmed with confidence that if the island was ever 
traversed by a glacier the crater-bearing cones are of 
later origin. 
St. Matthew and Hall islands are also volcanic, but 
without constructional forms. The period of eruption was 
so remote as to give time for the complete subsequent re¬ 
modeling of the surface by weathering and erosion. The 
coast shows a succession of cliffs, with rare bays and 
spits, and is evidently retreating rapidly before the attack 
of the waves. The higher slopes, though sometimes 
steep, are in general mature, and well adjusted to the con¬ 
ditions of erosion in a climate which obstructs the flow 
of water by clothing all surfaces with a sponge-like mantle 
of mossy and herbaceous vegetation. I saw nothing of 
the peculiar forms characteristic of glacial sculpture, but 
noted, on the contrary, a few blunt pinnacles projecting 
from the general surface and exhibiting such ragged de¬ 
tails as one does not find in glaciated regions. Figure 90 
represents one of these which happened to come within 
the field of a photograph. 
The ordinary landing at Port Clarence is upon a long 
spit, but we visited the mainland also, going ashore at a 
point where a gently undulating surface rises within a 
few miles to hills several hundred feet high. The rock is 
