iv PEOCEEDINGS OF THE GEOLOGICAL SOCIETY. [April 1914, 



natural causes, but from the point of view of investigating the 

 properties of flint. What he was endeavouring to elucidate by 

 experiment was the manner in which flint chipped when subjected 

 to forces of measured strength applied in different directions. 

 Many methods were being used, one of which was that of move- 

 ment under pressure of a sled, which could be loaded at will with 

 different weights. This process resulted in the reproduction of the 

 Kentish form of 'Eolith,' a load of 250 lbs. being sufficient 

 for the production of most of even the larger forms. It was, 

 however, insufficient for the reproduction of the big chipping 

 often present upon the sub- Crag flints. 



In considering subsoil pressures, in a soil of medium weight 

 (a clay-with-flints) a stone having a superficial area equal to a 

 rectangle of 8 by 6i inches was under a pressure of 250 lbs. at 

 slightly less than 6 feet below the surface ; at a depth of 50 feet 

 the same stone would be under about 9 times that pressure, while 

 beneath 500 feet of ice it would be under 40 times that pressure. 

 It was important to remember that striated surfaces were associated 

 with both the Kentish ' Eoliths ' and the sub-Crag flints, and these 

 pointed to the conclusion that strong movements under pressure 

 had actually operated upon the flints in question. 



Although the speaker did not wish to postulate too close an 

 analogy between experimental and natural conditions, yet, if, 

 broadly speaking, the chipping properties of flint discovered by 

 experimental investigation could be relied upon as also applying- 

 under natural conditions, then such chipping as was seen on the 

 flints in dispute might theoretically be expected to occur. 



A small series of chipped flints obtained from the base of the 

 Tertiary beds at Harefield was also exhibited. In this section the 

 bulbous chips could be found in the facets of the parent blocks, 

 from which the} 7 " had been forced away by the operation of subsoil 

 pressure. 



Mr. A. S. Kennabd exhibited, on behalf of Mr. B. Haeeisox, 

 a series of Eoliths from the Chalk Plateau of West Kent. This 

 type of worked flint was first described by the late Sir Joseph 

 Prestwich, and had formed the subject of a considerable literature. 

 It is obvious that the Palseoliths cannot be the earliest efforts of 

 man, and, although some of the stratigraphical evidence of the 

 Plateau is conflicting, yet, on the whole, it would appear that the 

 ' Eoliths ' are older than the Palaeolithic gravels. This is clearly 

 seen at Swanscombe, where the ' Eoliths ' are certainly derivatives. 

 In South Africa a similar sequence can be shown, and this is of 

 the utmost importance. It was quite impossible to say definitely 

 where the Avork of Nature ended, and that of Man began. It 

 was purely a personal matter, but the speaker was confident that 

 many of these rudely-chipped flints were human artefacts. As a 

 group, thev differed from the sub-Crag flints and many other 

 so-called ' Eoliths.' 



