540 HISTORY OF GEOLOGY AND PAL/EONTOLOGY. 



local moraines and the foldings and disturbances in the strata 

 at the base of the glacial deposits are looked upon as having 

 been produced by the pressure of the advancing masses of ice. 



The effects of the erosive activity displayed by the glacial 

 water are apparent in the giant-cauldrons, in the frequent 

 pools, peat-bogs and circular lake-depressions, and in the 

 long, narrow channels which extend almost parallel with one 

 another in directions perpendicular to the southern margin of 

 the former ice-sheet. 



" While the researches between the North German plain had 

 in view, on the one hand, to establish the chronological sub- 

 division of the glacial deposits with the help of the fossiliferous 

 strata, they have also been directed to explore the glacial and 

 interglacial accumulations which bestrew the plain, and to 

 determine the glacial system of hydrography. One of the 

 most important results has been the proof that ridges of end- 

 moraine extend throughout North Germany from the northern 

 borders of Schleswig-Holstein to West and East Prussia, as 

 well as the southern provinces of Posen and Silesia. The 

 observation that the ground-moraine of the last era of glacia- 

 tion presents the same features in front of and behind the 

 band of end-moraines, indicates that these accumulations 

 mark progressive stages in the retreat of the last ice-sheet, and 

 originated during the pauses in the general movement of with- 

 drawal. The detailed study of these hillocks and ridges of 

 end-moraine, and the phenomena associated with them, first 

 supplied the clue to the elucidation of the landscape features 

 which owe their origin partly to glacial erosion, partly to 

 glacial and fluvio-glacial deposition. By this means, also, it 

 became possible to distinguish the different types of lakes 

 characteristic of this extensive area of ancient glaciation. 



"The glacial hydrography of the North German plain has 

 recently had new light thrown upon it, in so far as the leading 

 lines of ancient valleys have been brought into connection 

 with the end-moraines of the inland ice. This has afforded an 

 explanation of the successive origin of the great east-west 

 valleys, each more northerly valley being younger than the next 

 valley on the south. The ice in the last period of melting 

 withdrew to a more northerly position, and at each pause in 

 the withdrawal, the waters which had previously been stemmed 

 back by the end of the ice-sheet found a new way of escape." 

 (Wahnschaffe, Zeitschr. d. d. geol. Ges., 1898.) 



