1 1 8 K. KEILHA CK 



concerned in the geological exploration and mapping of the 

 north German plain, I am bound to say that the fourfold classi- 

 fication of the north German glacial formations, given by Geikie, 

 in no way corresponds to our observations, nor to the statements 

 published in the " Explanations to the geological special map of 

 Prussia and the Thuringian states," or in the annual report of 

 the Royal Prussian Geological Survey, and in other places. 

 After many years of careful work in the territory referred to, we 

 find no conclusive reason for ascribing the ground moraine, 

 designated by us as the upper bowlder clay, to more than one 

 ice epoch. On the contrary, all of my colleagues who are or 

 were occupied in the territory of the terminal moraine of the 

 Baltic range, are, like myself, firmly of the opinion that the 

 youngest ground moraine in front of and behind the terminal 

 moraine, was deposited at one and the same time, by one and 

 the same mer de glace distinct from and younger than that which 

 deposited the upper bowlder clay of the territory of middle 

 north Germany. 



I must next consider the reasons which guided Geikie in his 

 reference of the Upper Diluvium (drift) of north Germany to 

 two glacial periods. They are stated in the second edition of 

 the Great Ice Age, and seem to me to be essentially traceable to 

 the four following points of view : 



1. In different localities the ground moraine of the epoch of 

 most extensive glaciation (Saxonian stage) contains (on account 

 of the different directions of movement, radiating from the north 

 of Scandinavia) bowlders quite different from the ground 

 moraine of the younger inland ?ner de glace, which moved in the 

 direction of the Baltic. According to Zeise the lower ground 

 moraine of Schleswig-Holstein, is, so far as concerns its con- 

 stitution, in no way different from the lower ground moraine of 

 the moraine district, so the former cannot be the equivalent of 

 the lower bowlder clay of the Mark, Posen, etc. 



2. In Finland two systems of glacial striae are developed ; an 

 older one, which thus far has been observed only outside the 

 territory enclosed by the terminal moraine, and a younger one 



