FLINT FRACTURE AND FLINT IMPLEMENTS 45 



(b) The fact that the former had cut deeper into the flint, 



causing a step or ledge to appear at the point of their 

 final separation from the parent block (fig. 6) ; and 



(c) The occurrence of numerous prominent ripple-marks 



upon nearly all of the flakes produced by fortuitous 

 blows, as compared with their comparative scarcity 

 upon the " human " flakes (fig. 6). 



The explanation of these differences may be explained as 

 follows : 



In intentional human-flaking, a flat striking platform is 

 produced, and blows are delivered on one or other side of this 

 platform, and in such a manner that the flakes removed are 

 generally the reverse of squat, being of greater length than 



P6R.CUSSION . 



Fig. 6. 



OlMRCTEMVtic 



Fig. 7. 



Fig. 8. 



width, and thinnest at the point of their final separation from 

 the parent block (fig. 7). Such flakes are also generally free 

 from prominent ripple-marks, due, in the author's opinion, 

 to the fact that the blows which detached them were delivered 

 almost vertically to the striking platform. In flaking pro- 

 duced by fortuitous percussion the great majority of the blows 

 fall, not upon the side of the edge of the flint, but almost directly 

 upon the edge itself, and it is known that blows so delivered 

 remove flakes squat in form and productive of a step or 

 ledge at the point of their final separation from the parent 

 block. 



It has been ascertained that consistently to remove flakes 

 exhibiting prominent ripple-marks upon their surfaces, it is 

 necessary to strike the flint an oblique blow. As has already 

 t>een mentioned, a blow delivered vertically to a flint surface 



