* 
Drift of the North German Lowland.—NSalishury. 301. 
cited as evidence of the greater youth of the surface of this re- 
gion. Nor does Dr. Wahnschatfe refer (4) to the more extensive 
disintegration of the bowlders of the drift in the southern part of 
Germany,as compared with that of the bowlders in the northern. 
Ditferences in the direction of the movement of the ice at differ- 
ent times, as indicated by differences in the direction of striae, and 
especially as indicated by the different regions from which material 
was successively transported to a given region, also constitute 2 
valuable criterion when taken in connection with the points above 
stated. In his chapter on striz Dr. Wahnschatfe refers to the 
phenomena which indicate different directions of ice movement. 
But in discussing the question of two glacial epochs, these diver- 
gent movements are not made to support the theory of two ice 
epochs. 
The foregoing are among the criteria which are especially relied 
upon in America as proving a recurrence of glaciation at widely 
separated intervals. We believe they are much safer and more 
widely applicable criteria than those given in the volume before 
us. My own study of the drift formations of (rermany in 1887 
and 1888 convinced me that the third and. fourth points stated 
above are as well illustrated in Germany as in America. In my 
judgment they are of more significance as indicating a long in- 
terval between the deposition of the earliest and latest glacial 
formations in Germany, than all the fossil remains of whatever 
sort, which have yet been described. 
EBetent of Second Glaciation. As in America, the extension 
of the ice in Germany, in the second epoch, according to our 
author, was much less than in the first. The limits of the last 
ice advance however are still in doubt. It extended at least so 
far as to cover the eastern part of Schleswig-Holstein, Mecklen- 
burg, a large part of Brandenburg, Pommern and Kast and West 
Preussen. While some of the German geologists would limit the 
second ice invasion in the western part of Germany to the lower 
course of the Elbe, Dr. Wahnschatfe believes that there is sufli- 
cient evidence that it extended further south. Tle finds traces of 
the work of the ice sheet of the second epoch in the vicinity of 
Magdeburg. He also believes that the bowlder-bearing sand which 
covers the ‘“Luneburger Heide” southwest of the Elbe, is last 
glacial. The basis for this conclusion concerning the sand of the 
“Luneburger Heide” is not fully given. A single crossing of the 
