72 



SOCIAL EVOLUTION 



tiiic't, or no longer the same as those in the surrounding 

 waters.^*^ But while the position in or under the drift 

 which some glacier or glacial river has transported and 

 finally deposited in over accumulating layers, constitutes 



From Birkuer, " Der Diluviale Mensch ia Euiopa." 



Figure 2G. Diagram of Cro-Magnon Grotto, where Remains of Pre- 

 historic !Men were foiuul. 



quite conclusive evidence, the position under stalagmite 

 beds and kitchen-middens does not furnish as reliable 

 proof of antiquity. The growth of stalagmite beds is 

 irregular and depends upon conditions which are sub- 

 ject to some variation. In the case of the kitchen-mid- 

 den, some shells are accumulated with great rapidity 

 so that in a comparatively short time a considerable pile 



30 Keane, ojj. cit., pp. 70-77, 96. 



