ARTICLES 93 



mate so far as it is an expression of the fact that most of our 

 knowledge of the one series is derived from caves, and of the 

 other from the drift ; but the view is steadily gaining ground 

 that, while implements of the latter series may be found in 

 caves, most, if not all, of the principal cave industries are repre- 

 sented in deposits which we cannot logically separate from the 

 drift ; and so, if we adopt these terms, we reach the rather 

 absurd position that drift continued to be formed and to 

 enclose palseoliths long after the Drift Period had come to an 

 end. The terms Upper and Lower Palaeolithic are therefore 

 decidedly preferable, though whether the line between them is 

 rightly drawn at the close of the Acheulean industry is another 

 question altogether. 



Mousterian. — Implements of this period are found by 

 M. Commont in the Somme valley at all levels from the plateau 

 almost down to the river, but it is only on the lowest terrace 

 that they are buried in true river deposits. Elsewhere they 

 occur in the subaerial dernier loss, and are thus stratigraphically 

 distinct from the Acheulean industry of the loss ancien. M. 

 Commont, however, attributes to the Mousterian period a cer- 

 tain number of hand-axes which are not clearly distinguish- 

 able in his figures from those of Acheulean age ; and one 

 gets the impression, which an examination of the actual 

 specimens might perhaps dispel, that the two industries are 

 not so sharply separable geologically as he represents them. 



In England also these implements are found at various 

 levels, but in many cases they are buried in " brick-earth " — 

 an ill-defined term which probably covers a number of deposits 

 of different age and origin, some being certainly fluviatile, 

 while others are probably subaerial ; and this makes it very 

 difficult to arrive at a definite decision as to the range of varia- 

 tion of the river-level during this period. 



Several flakes attributed by Messrs. Leach and Chandler 

 to this industry were found at Wansunt, in a clay which is 

 certainly fluviatile, and which, as we have seen, is regarded 

 by some writers as the last deposit of the ioo ft. terrace. If 

 this diagnosis is correct, then the Mousterian and Acheulean 

 industries were here co-existent ; but great caution is required 

 where only small numbers of specimens are present, since flakes 

 were used also in Acheulean (and earlier) times, and no exact 

 criteria for distinguishing them from those of Mousterian age 



