STUDIES FOR STUDENTS. 83 
sides of overhanging cliffs, in horizontal grooves in vertical or 
sloping faces. 
Except where icebergs grounded, any deposits they might make 
would be made through water. They should be largely stratified, 
although the type of stratification developed by the dropping of 
coarse and fine material through still water might be recogniz- 
ably different from that developed in deposits made along shores 
or by running water. The type of stratification which affects the 
larger part of the stratified drift, is the stratification developed 
by rapidly moving streams. It is not the type of stratification 
which would be developed in material dropped through still 
water. Further, the relations which subsist between the stratified 
and the unstratified drift are not such as would exist if the drift 
were the work of icebergs. Were there no other insuperable 
difficulties in the way of supposing that icebergs were responsible 
for the drift, we should find it in the constitution of the drift. 
It will be remembered that the agents which deposited the drift 
at any given point, were generally agents which had gathered 
material all along a somewhat extended course, and that in general 
the larger part of the material which they left at any given point 
had been derived from sources close at hand. This is just the 
work which icebergs cannot do. They can carry such material 
as they possessed when they set sail, but they can gather noth- 
ing along the course of their journey. 
Furthermore, if the whole of the drift-covered country were 
submerged, as must needs be if icebergs alone are to explain the 
drift, where was the land which nourished the glaciers whence 
the icebergs came? 
' From these considerations it seems certain that icebergs were 
not the sole or the principal agents of the drift. Were all the 
characteristics of the drift and all the phenomena accompanying 
it examined in detail, the result of their combined testimony 
would confirm the conclusions to which this partial examination 
has led. This would still remain true, even though certain feat- 
ures of the drift might seem to find adequate explanation in the 
icebergs. Since icebergs were not the sole or the principal agents 
