GEAGALE SERODIES IN GREENEAND. 207 
conditions, a typical bowlder clay, or, if not, at least a distinctive 
bowldery silt or bowldery sand which clearly stands in its stead. 
But of much more consequence is the fact that the clastic 
series forms only a narrow belt along the coast, and that the 
limits of this, in chosen cases, can be closely determined, so that 
the extent to which drift has been transported can be approxi- 
mately learned. From this the intensity of the glacial action 
may be estimated by a comparison of the amount of abrasion with 
the distance of transport. Of more consequence than this, even, 
is the opportunity afforded for observing the position of material 
of known source in the ice, and hence of judging of the con- 
ditions under which the material is introduced into the ice, the 
method of its introduction, and the course it pursues in the ice. 
It has been the growing conviction of students of the Pleisto- 
cene drift that a large percentage of the material was derived 
from points not very distant from the places of final deposition. 
The opportunity to determine how far such local action is the 
habit of the Greenland glaciers is, therefore, one of the felicitous 
features of the Inglefield Gulf region. 
Glaciers of Northumberland Island —At the mouth of Ingle- 
field Gulf lie two very considerable islands, Northumberland and 
Herbert. These present interesting phases of local glaciation 
that are worthy of a passing word, though it can only be a very 
general one, as they were merely observed from a distance while 
the vessel was detained in the vicinity by the ice. On Northum- 
berland Island a considerable ice field accumulates, although 
its elevation is apparently much short of 3000 feet, and several 
small glaciers creep down to the vicinity of the sea level. While 
the plateau surface contributes measurably to the formation of 
the glaciers, their gathering ground seems to be chiefly in amphi- 
theatres at the heads of valleys, which have developed notable 
dimensions and taken on the form of circs. Their peculiarity is 
a circ-like development in the margin of the plateau, combined 
with an inflow from the plateau surface above. The accumula- 
tion of snow is perhaps more due to the lodgment of the wind 
drift in the amphitheatres than to direct precipitation. In sur- 
