84 SCIENCE PROGRESS 



Chellean. At Chelles itself (on the Seine), and in Belgium, 

 implements of this type are found but little above the level 

 of the river ; but in the Somme vallej 7 they have a wider range, 

 occurring on the first, second, and third terraces at elevations 

 of 10, 30, and 40 metres respectively above the river, but 

 they are absent from the fourth terrace (50 metres). While 

 the implements of the second and third terraces are identical, 

 some of those on the first terrace are of an apparently more 

 advanced type, called by M. Commont Chelleen evolue. 1 



Both in level and in the character of its implements the 

 100 ft. terrace of the Thames at Swanscombe closely resembles 

 the second terrace of the Somme, and it is not quite clear 

 on what grounds Messrs. Smith and Dewey correlate it with 

 the third terrace. 2 It is true that the marne blanche below 

 the Chellean gravel at Abbeville (third terrace), which seems 

 to correspond to the white marl between the Chellean and pre- 

 Chellean gravels at Swanscombe, is absent on the second 

 terrace at St. Acheul ; but the same terrace at Menchecourt 

 has a closely similar marne sableuse legerement coloree, also con- 

 taining shells 3 : on the other hand, no human work at all 

 occurs at Abbeville either in or below the marne blanche, so 

 that in this respect the parallel drawn by Messrs. Smith and 

 Dewey is at present incomplete. 



Although the gravel of the 100 ft. terrace rises to over 130 

 ft. O.D. at Dartford (and therefore to the level of the third 

 terrace of the Somme), implements are extremely rare in that 

 locality ; but in the Hampshire basin (Bournemouth and the 

 Avon valley) they are often found up to and above this level, 

 though not on a separate terrace. Occasionally, too, the}?" 

 occur at a height of several hundred feet above the present 

 river level, not merely on the surface, but, it seems, actually 

 buried in gravel : but while it is doubtful whether these high- 

 level specimens (to which we shall return later) can be matched 

 in France, it is equally uncertain whether the Chellean and 

 Chelleen evolue of the lower terrace of the Somme have their 

 equivalents in England. Unabraded implements not infre- 

 quently occur at low levels (30-50 ft. above the rivers) both 

 in the Thames valley and in Hampshire, but they have not 



1 Ann. Soc. Ge'ol. du Nord, vol. xxxix. (1910), p. 284. 



2 Archirologia, vol. lxiv. p. 197. 



3 Ann. Soc. Ge'ol. da Nord, vol. xxxix. (1910), p. 276. 



