126 PREHISTORIC EUROPE. 



alike. These, Professor Prestwich was the first to show, all 

 belong to one series, and the wide-spread " loss " or loam and 

 brick-earth, he likewise included as part of the same pheno- 

 mena. 



An exhaustive examination of the gravels and loams in a 

 number of the valleys in the north of France and the south of 

 England enabled this geologist to demonstrate that they had 

 been formed by river-action. This was shown by the pebbles 

 themselves, all of which had been derived from the strata in 

 which the valleys are excavated. Not only so, but they had 

 also travelled in the same direction as the present streams. 

 The fluviatile origin of the gravels in question was still farther 

 proved by the notable fact that land- and freshwater-shells were 

 often met with in high- and low-level deposits alike, while 

 marine remains, save in the immediate neighbourhood of the 

 sea, were entirely wanting. 



From these old " river-drifts " flint implements of undeniable 

 human workmanship have been obtained in large numbers, and 

 associated with them, in the same undisturbed strata of sand 

 and gravel, numerous remains of the Pleistocene mammalia have 

 been found. The observations of Boucher de Perthes have thus 

 been verified by Professor Prestwich, as also by many French 

 and English geologists. There can be no doubt, therefore, that 

 man and his congeners, the extinct and no longer indigenous 

 mammalia, were in joint occupation of France and Southern 

 England during the deposition of the ancient valley- deposits 

 whose origin we are now considering. 



One of the most remarkable characteristics of these gravel- 

 and loam-beds is the height they frequently attain above the 

 present levels reached by the streams and rivers. They are 

 traced in patches and often in more or less continuous sheets 

 up to a height in some cases of as much as 150 feet above the 

 bottoms of the valleys. It is evident, therefore, that the rivers 

 at one time flowed' at elevations which they do not now attain 

 even during the heaviest floods. Professor Prestwich has shown 

 very clearly how impossible it is that the formation of the higher 



