336 JAMES GEIKIE 



arate ice-sheet, and the moraines of retreat that occur behind 

 them. 



The southern limits of the Polandian ice-sheet in Britain and 

 Germany alike is bordered by more or less thick banks and 

 sheets of morainic gravels. These are the only terminal 

 moraines connected with the ground-moraine of that ice-sheet. 

 Although the surface of that ground-moraine is often abun- 

 dantly strewn with fluvio- glacial detritus it shows no lines of ter- 

 minal moraines comparable to those of the Baltic Ridge in 

 Germany and of the valley -glaciers and local ice-sheets in 

 Britain. The latter bear witness to vigorous glacial action — 

 they have not merely been dumped upon the ground, for the 

 local ice-flow has in many places ploughed into and pushed up 

 preexisting bowlder clay and ground out hollows in the solid 

 rocks. The terminal moraines of the Baltic Ridge no doubt con- 

 sist largely of water-worn materials, just as is the case with the 

 moraines of all sheet-like or Piedmont glaciers, and much of the 

 material has been dumped. But they also yield evidence of 

 glacial push, for ground-moraine, confusedly commingled with 

 gravel and sand, not infrequently enters into their composition. 

 The lines of moraines and the irregular mounds, banks, and 

 sheets of water-worn materials which are distributed over the 

 ground between the Baltic Ridge and the shores of the Baltic 

 Sea are simply moraines of retreat and fluvio-glacial deposits, 

 and I hope no "fanatical" giacialist will "terrify" either him- 

 self or Dr. Keilhack by suggesting that they indicate "four if 

 not five" separate glacial epochs. 



(5) Dr. Keilhack further objects to my conclusion that the 

 terminal moraines of the Baltic Ridge mark the limits of an inde- 

 pendent glaciation, because he thinks these moraines cannot be 

 correlated, as I have supposed, with the Alpine valley-moraines 

 belonging to Professor Penck's "first postglacial stage." The 

 Baltic Glacier of my fourth glacial epoch .(Mecklenburgian) , 

 according to him was of such immense size and so little inferior 

 to the ice-sheets of earlier stages that such correlation as I have 

 attempted is almost impossible. And he gives a graphic repre- 



