EBUROPEAN GEACIAL DEPOSITS. 255 
interior of the continent a climate even more genial than that 
which now obtains. Further, the long duration of the Hel- 
-vetian epoch is shown by the extensive valley-erosion then 
accomplished. We may conclude that, at the climax of this 
particular interglacial stage, the snow-fields and glaciers of 
Europe were of no more importance than they are in our own 
day. 
If this conclusion be well sustained it is obvious that the ice- 
sheet of the Polandian stage was separate and independent, and 
not a mere phase of the greater Saxonian mer de glace. The 
latter had for a long time disappeared before the minor ice-sheet 
came into existence —and the independence of the latter is still 
further shown by the fact that its path differed in some impor- 
tant respects from that followed by the earlier ice-flow. In 
Saxonian times the Baltic basin had little influence upon the 
general direction of the mer de glace, while the course of the 
succeeding Polandian ice-sheet was obviously to a large extent 
controlled by that great depression. And similar remarkable 
differences in the directions followed by the two ice-sheets have 
been detected in Britain. 
From the Scanian to the Polandian the succession is easily 
read, but from this stage onwards the evidence is rather harder 
to follow. My own investigations in Britain led me long ago to 
conclude that climatic oscillations had continued to take place 
after the formation of our upper bowlder-clay. I found, for 
example, that subsequent to the retreat of the minor mer de glace, 
underneath which that upper till had accumulated, there super- 
vened an epoch of district ice-sheets and valley-glaciers. The 
evidence showed clearly enough that the upper till had been 
partly ploughed out and large terminal moraines piled upon its 
surface by a still later series of ice-flows. But as no interglacial 
beds have hitherto been detected between the moraines in 
question and the underlying bowlder-clay I could not be sure that 
the epoch of large local glaciers had been separated from that 
of the Polandian stage by any long interval. It seemed possible 
that the valley-glaciers were merely the degenerate successors of 
