298 The American Geologist. - May, 1892 
references cited in support of the position that subglacial material 
may become superglacial, are based on observations on existing 
Alpine glaciers. Here the supposed transfer of stony material 
from the bottom of the glacier to its upper surface is accompanied 
by conditions which would not exist, or which would not exist to 
the same extent in plane regions. I believe it is true that the 
transference of subglacial material to a superglacial position is 
facilitated by these conditions, if not entirely dependent on them. 
The ice-sheet which invaded Germany had descended from a 
mountainous region. The ice-sheet which invaded the United States, 
while it descended from high lands, did not start from, or pass over, 
a region nearly so mountainous as that of Scandinavia, from which 
the German ice-sheet took its source. It would be expected there- 
fore that Germany would be more favorable territory than the 
United States for the development of superglacial till, whatever the 
process by which it became superglacial. Under these cireum- 
stances it would seem that if any difference exist between the quan- 
tity of superglacial till in the two countries,Germany should have 
the more. Dr. Wahnschaffe’s opinion as to the paucity of super- 
glacial till in Germany is therefore significant, and is in harmony 
with the writer's opinion concerning the same sort of till in the 
United States. 
The Ground Moraine. Dr. Wabnschatte discusses the method 
of transportation and deposition of the ground moraine. The 
views of the various German Geologists who have expressed opin- 
ions upon the subject are cited and discussed. Heim is cited as 
holding the opinion that material can be carried forward beneath 
the ice only where and when it is frozen to the ice itself. Haas 
introduces variety, if not value, into the series of opinions con- 
cerning the method of deposition of the ground moraine, by sup- 
posing that wherever the thickness of the ice was considerable, its 
weight must have converted its lower portion into water, so that 
between the ice and the land surface beneath it there was a layer of 
water in which the deposition of the till took place,and that the ice 
really rested upon the land surface only near its margin where its 
thickness was not great. From this view Dr. Wahnschatfe dissents. 
He adyocates the view—so far as the writer is aware the only one 
ever held by glacialists in America—that the ground moraine was 
accumulated gradually beneath the ice. The lower portions of 
any considerable body of till in any given loéality, are therefore 
