1897] THE AUTHENTICITY OF PLATEAU MAN :'»29 



certain amount of polishing by the action of blown sands. Some- 

 times the whole surface of the flint has been thus polished, but 

 specimens often occur in which the action has been limited to one 

 side. Many of the flints of the Thames gravels, as, for example, at 

 Clapham, show the same feature. In the cases of these low level 

 gravels, the polishing was probably effected at a time of drought, 

 when the pebbles were exposed and the river sand was dry and loose. 



We therefore see that these plateau flints have been subjected 

 to six different processes, all of which are undoubtedly natural, and 

 each of which has left clearly recognisable traces. Taken in order 

 of date, the processes are : — 1st, splitting of the original flints into 

 slabs, probably by frost ; 2nd, a deposition of a siliceous encrusta- 

 tion ; 3rd, iron staining ; 4th, scratching by some glacial agent ; 

 5th, deposition of a second siliceous encrustation ; 6th, polishing by 

 blown sand. 



This series forms a chronological table by which we can 

 determine the relative dates of the various chippings of the flints 

 which are affirmed to be the work of man. I think it is quite clear 

 from the evidence of the flints that natural agencies are sufficient to 

 account for every splinter and scratch that they exhibit. 



The first fact that tells against the artificial chipping of the 

 flints is that the chipping is of very different dates. The process 

 must have been continued for a considerable length of time. It is 

 not difficult to distinguish between the chippings of different periods. 

 The earliest fractures are the largest, as might be expected, since the 

 conditions were the most rigorous. As the climate became milder 

 the forces that acted on the flints became feebler, and the chips 

 removed were therefore smaller. On some specimens it is possible 

 to detect chippings of three different periods. The first set were 

 struck off before the flints were coloured red ; the second set broke 

 acrpss the margins of the first, and sometimes exposed part of the 

 uncoloured flint below. Then came an interval during which the 

 glacial scratches were made. These scratches cut across the surfaces 

 formed by the first two sets of chippings. The fractures of the third 

 set, on the other hand, are never scratched, but have themselves cut 

 across the striae. These latest chips were small, and usually more 

 distinctly conchoidal than the others, and in many instances they 

 present the appearance of small frost-flakes. 



As definite illustrations of the different dates of the chippings, 

 let us examine in detail four flints which were given to me by Mr 

 Harrison as fairly good implements (Plate IX.). 



The first is shewn in Fig. 1 of the Plate. 1 It was found by Mr 

 Harrison at South Ash, and is numbered 4997. Its size is 6 cm. 



1 For the photographs I must express my indebtedness to Mr T. H. Powell of 

 Denmark Hill. 



