544 PREHISTORIC EUROPE. 



action of severe frost, and pertain for the most part to the close 

 of the Pleistocene. 



We come, then, to the conclusion that the alluvial and cave- 

 deposits of the Pleistocene were accumulated during a prolonged 

 period, when the climate of Europe experienced several great 

 changes, and when the fauna and the flora were compelled to 

 perform secular migrations. Now, a close analysis of the glacial 

 deposits of the mountainous regions and northern latitudes of 

 Europe demonstrates that the Ice Age was not one long con- 

 tinuous period of arctic conditions. It was interrupted several 

 times — how often we cannot yet say — by Interglacial epochs of 

 mild and genial conditions, during which the central and north- 

 western areas were occupied by the same fauna and flora which 

 we meet with in the river- and cave-accumulations. And the 

 conclusion is forced upon us that the so-called Glacial Period, 

 with its alternations of severe arctic climate and mild and 

 genial conditions, is one and the same with the Pleistocene 

 Period. "We cannot escape from this result — it follows as a 

 logical induction from indisputable and demonstrable facts. 

 Let us take, for example, the relation of the valley-loss to the 

 Pleistocene river-gravels on the one hand, and the later glacial 

 deposits on the other. We have seen that everywhere this loss 

 overlies, and is therefore of more recent date than the younger 

 valley-gravels. It is characterised by the presence of molluscs 

 which imply cold and wet conditions, and of mammals of high- 

 alpine and northern habitats. In it and underneath it we 

 obtain relics and remains of Palaeolithic man, while not a trace 

 of these, or of any of the southern mammals with which the 

 men of the Old Stone Age were contemporaneous, occurs upon 

 its surface or in the later accumulations of peat and alluvium 

 which rest upon it. The valley-loss, then, is the youngest allu- 

 vial deposit of Pleistocene age. But nothing can be more certain 

 than this, that it is also the latest fluvio-glacial accumulation of 

 the Glacial period. It is the loam carried down by the enor- 

 mously flooded rivers of the last cold epoch of the Ice Age. 

 The remarkable distribution of the ossiferous and Palaeolithic 



