378 RELATION OF THE LOESS TO THE GRAVEL. 



floods were perhaps more destructive to animals even than 

 man himself ; while, however rude they may have been, our 

 predecessors can hardly be supposed to have been incapable 

 of foreseeing and consequently escaping the danger. 



While the water had sufficient force to deposit coarse gravel 

 at any given level, at a still higher one it would part with 

 finer particles, and would thus form the loess, which at the 

 same time would here and there receive angular flints and 

 shells brought down from the hills in a more or less transverse 

 direction by the rivulets after heavy rains. 



Mr. Prestwich regards the difference of level between the 

 upper gravels and the loess as " a measure of the floods of that 

 period." If the gravel-beds were complete, this would no 

 doubt be the case ; but it seems to me that the upper-level 

 gravels are mere fragments of an originally almost continuous 

 deposit, and under such circumstances the present cannot be 

 taken as evidence of the original difference. 



As the valley became deeper and deeper, the gravel would 



FIG. 204. 



CHALK 



Diagram to show the Relations of the Loess and the Gravels. 



be deposited at lower and lower levels, the loess always fol- 

 lowing it ;* thus we must not consider the loess as a distinct 

 bed, but as one which was being formed during the same time, 

 though never at the same place, as the beds of gravel. In 

 fig. 204 I have given a diagram, the better to illustrate my 

 meaning ; the loess is indicated by letters with a dash and is 



* See Mr. Prestwich's paper read before the Royal Society, June 19, 

 1862. 



