220 PREHISTORIC EUROPE. 



At present the winter temperature (January) of Gibraltar is 

 54°'7 F., while that of Malta is 54°'5 F., so that it is not un- 

 reasonable to suppose that during the Glacial Period heavy snow 

 in winter may have covered the more elevated parts of Malta, 

 and hard frost may have ruptured the rocks in the same manner 

 as at Gibraltar. Much angular dShris and masses of broken 

 limestone and sandstone would thus tend to gather and be 

 swept down into hollows and over the faces of cliffs, so as to 

 form long, sloping taluses. 



In the same way I would account for much of that loose 

 earthy rubbish with angular blocks which one may observe 

 in the lower valleys of the Apennines and the Apuan Alps, and 

 indeed in nearly every part of Europe. The quantities of more 

 or less loose angular debris which one encounters almost uni- 

 versally in districts where no such d6bris is now accumulating 

 or travelling forward, speak to conditions of transport which 

 now obtain only in more elevated and northern regions. " Such 

 drifts deserve," as the Eev. W. S. Symonds has remarked, 1 

 "especial attention;" and I quite agree with him that "they 

 appear to owe their origin to a period when there was greater 

 transportation of angular and sub-angular debris by rain-wash 

 and melting snow, or n&o6, than there is at present." It is 

 highly probable, for example, that much (I do not say all) of 

 that coarse loamy clay with angular flints which M. de Mercey 

 has described as being so widely spread in Picardy may be due 

 to the action of frost and the movement of heavy sheets of 

 ndv4, which in some places, perhaps, may have passed into ice, 

 and exerted considerable erosive action upon the rocks over which 

 it crept. Of the Pleistocene age of this particular deposit there 

 can be no doubt. But in other areas of Northern France we find 

 similar wide-spread sheets of clay and sand which have been 

 assigned by French geologists sometimes to the Pleistocene, and 

 sometimes to Tertiary periods. Among the most remarkable 

 examples of such superficial accumulations are those which 

 overlie the Cretaceous strata of the Paris Basin. They have 



1 Nature, vol. xiv. p. 179. 



