318 The American Geologist. May, 1992: 
esting as the history of opinion on this point is, we shall content 
ourselves at this time with mentioning only Dr. Wahnschatfe’s 
views. Be it remarked, however, that it has always seemed to- 
the writer that much of the discussion concerning the origin of 
the German lakes, masked a broader question, which embraced 
the narrower one discussed. Enclosed depressions are one of the 
conspicuous features of the ‘‘ground moraine landscape.” Many 
of these depressions do not become lakes because of pervious bot- 
toms. But the dry ‘‘kettles” are just as significant as those filled 
with water. The depressions are associated with hills and ridges 
which constitute the second conspicuous feature of our terminal 
morainic topography. ‘The association of these two features is 
such as to make it necessary to suppose that the explanation of 
the one must take account of the other ; that the processes which 
called forth the one, were responsible also for the other. The ques- 
tion at issue, therefore, is not the origin of the lake basins, but 
the origin of the ills and basins (whether occupied by water or 
not), that is, the origin of the ‘‘ground moraine landscape” (our 
terminal moraine ) topography. This is not so much a criticism 
of Dr. Wahnschatfe’s discussion as a comment upon some of the 
discussions which have preceded this volume, and which are cited 
in it. 
Dr. Wahnschatfe recognizes several classes of lakes. One class 
is designated the ‘‘ground moraine lakes ” (Grundmordnensecen). 
Itis to this class of lakes to which the foregoing comment is rele- 
vant, and Dr. Wahnschatfe does not regard their origin as a ques- 
tion distinct from the origin of the topography of the Baltic. He 
would therefore make the origin of these basins contemporaneous. 
with the origin of the topography with which they are associated. 
A second class of lakes are associated with the HLudmordne, and 
occupy depressions, of which this ridge constitutes one of the 
bounding walls. They are basins formed by morainic dams. A 
third class of lake basins are attributed to the eroding action of 
the waters arising from the melting of the ice, either as they 
plunged through crevasses, excavating small circular hollows. 
below, or as they flowed through their sub-glacial or extra-glacial 
courses. Many of the lakes which are connected with each 
other as beads on a string, are referred to such an origin. Still 
other lakes, few in number and small in size, may be the result 
of underground solution. 
