300 The American Geologist. May, 1892 
in which they were deposited by the sea, must mean a recession 
of the ice sufficient to allow the sea to occupy the area where they 
occur. But the question might be legitimately raised whether a re 
cessionof the ice no greater than these shell beds would necessitate, 
must necessarily be interpreted as proof of two glacial~ epochs, 
Such recession, particularly if of short duration, might be looked 
upon as no more than a great oscillation of the edge of the ice. 
The vertebrate remains in the sand and gravel layers between beds 
of till in the vicinity of Berlin, would seem to us to have thesame 
significance as the shell beds. So far as these fossils indicate a 
temperate climate, their significance as indicating a genial inter- 
glacial interval, is increased. Dr. Wahnschatfe does not give the 
species represented in these fossil beds, nor does he indicate the 
climatic conditions to which they testify. But if we are rightly 
informed, they are fossils of species which do not indicate a climate 
of great severity. The abundance of terrestrial mammalian re- 
mains in the gravel and sand separating beds of till in certain re- 
gions, is perhaps more significant than the abundance of marine 
shells in corresponding situations, since the mammalian remains 
accumulate more slowly. 
The evidences of more than one ice epoch which are most strongly 
relied upon by glacialists in America, are not brought out in the 
treatise before us. It would seem either that the evidences do 
not'exist inGrermany, or that they have not been made use of. The 
author does not indicate that there are in Germany (1) soils rest- 
ing upon till or any form of older drift, buried by later glacial 
formations. He does not indicate that there are (2) beds of drift 
whose surfaces are much weathered and deeply oxidized, now buried 
by later drift deposits, whose surfaces are much less weathered 
and oxidized; nor does he, in this connection, emphasize (3) the 
difference between the amount of sub-aerial erosion suffered by 
the surface overspread with the drift which is regarded as first 
elacial, as compared with that suffered by the surface overspread 
with drift which is regarded as second glacial. In another con- 
nection, the fact is referred to that the lakes of (rermany lie for 
the most part in and north of the Baltic ridge which crosses (rer- 
many in a course roughly concentric with the north German coast. 
This lake area lies wholly within the limits of the second glacia- 
tion, according to Dr. Wahnschatfe’s interpretation, but the 
abundance of lakes in the Baltic ridge and north of it, is not 
