124 Prof. Hughes, On some Chipped Flints from [Mar. 9, 



Mutatis mutandis we may offer the same explanation of the 

 origin of the superficial deposits along the North Downs of Kent 

 and of the mode of occurrence of gravels largely derived from 

 surface flints and from the destruction of the top of the chalk 

 which occur in that area, not only over the surface of the chalk 

 itself but over beds which crop out from below the chalk in front 

 of the great escarpment that overlooks the weald and over the 

 Tertiary beds which cling to the dip slope of the chalk on the 

 north as described in the works quoted above. 



The reason why it is of the greatest importance to clear up 

 this question is that, if the views now put forward are correct, 

 these deposits may be of any age and that they are even being 

 formed still. Some of the gravels on ledges and terraces, and the 

 outlying knolls which represent old ledges and terraces, may be 

 patches of trail or be due to rain-wash and soil-creep which have 

 used up remnants of older river gravels, while some of them may 

 be ancient river gravels which have largely if not wholly derived 

 their material from the surface. 



Sometimes it may be possible to refer a given bed to one 

 or other of these two gravels so different in mode of transport, if 

 not in the origin of the material. 



If many, perhaps most, of the patches in question have been 

 formed by the local rainwash and soil-creep, the height of the 

 deposit above the sea or above the existing rivers goes for nothing, 

 but, if we must suppose that an escarpment has receded far since 

 it fed the now outlying hills with its debris, we must admit that as 

 an argument in favour of an enormous lapse of time since the 

 objects found in the gravel were deposited where now found, or 

 we must believe in a much more rapid destruction of the chalk 

 than has been until recently advocated 1 . 



To consider now the character of the flints found on such 

 surfaces and in such deposits as those just described. 



A blow or crush takes off pieces of flint with a bulb of per- 

 cussion and a conchoidal fracture. Changes of temperature make 

 it crack and often remove large lenticular flakes which show no 

 bulb. This is what so commonly spoils flint implements which 

 have been lying long exposed on the surface of the ground. 



None of these operations necessitate the presence of man. 



Any movement which would force one flint against the other 

 would be likely to produce fractures. The stampede of a herd 

 of oxen or deer must make many a flake and chip the edge of 

 many a flint. 



The whole of the surface from Balsham to Six Mile Bottom 

 is covered with flints showing every variety of fracture. Most 



1 See Howorth, Geol. Mag. Feb. 1896, pp. 58 et seq. 



