6 The A)ncricaii Geologist. "^"'^"^ •^^*^-- 
of things exists about the head of the isubglacial stream on the 
east side, also near the junction of the first branch glacier on 
the east with the main stream, as also about the mouth of the 
independent glacier shown on the map lower down on the west 
side of the inlet." 
We have clearly indicated here a type of eskers in the form- 
ation of which running water is not an immediately active 
agent ; and, moreover, at the time of their filling by supergla- 
cial detritus, the subglacial tunnels have become gorges open 
to the sky and the deposits are not in any proper sense sub- 
glacial. Undoubtedly this is a true explanation of some kame- 
like and hummocky forms of modified drift: and it appears 
that, in general, deposits formed under these conditions would 
be more properly classed as kames than as eskers ; and no one, 
perhaps, supposes that the more typical eskers of New Eng- 
land and other districts covered by the Pleistocene ice-sheet 
have had this origin. 
The search for eskers along the borders of the Greenland 
ice-cap and its dependent lobes or glaciers has been even more 
fruitless ; and Chamberlin,* among recent competent observers 
in that field, has expressly noted the practical absence of this 
class of phenomena, attributing it chiefly to the inadequate 
drainage ; but in part, also, to the fact that glacial streams are 
mainly lateral, coursing along the margins of the ice lobes, while 
medial tininels of Alaskan and Alpine glaciers are wanting. 
According to Russell, the drainage of the glaciers of the Alt. 
St. Elias range, above their confluence with the Malaspina gla- 
cier, is, also, largely or chiefly by marginal streams, which, 
like the lateral moraines, unite at the lower ends of the moun- 
tain ridges and pass into or beneath the piedmont glacier. 
Nowhere, apparently, have esker-like deposits been formed 
by the subglacial streams of Alpine glaciers, owing in part to 
the high gradients of the valleys, and in part tO' the paucity 
of detritus and the consequent absence of deposits at the lower 
end of the tunnels of sufficient volume to efficiently clog the out- 
lets and lead to aggrading of the floors of the tvmnels. 
That observations on the existing ice of the northern hemi- 
sphere have made no important positive contributions to the 
theory of oskers, is, perhaps, not an overstatement. We may 
• BulL Geol. Soc. Am., 6. 215. 
