278 A Geological Sketch of the Valley of the Eennet. 



Common, in which large blocks of greyweather-sandstone occur. 

 Thus then we may account for the beds of gravel and their heter- 

 ogeneous nature. 



But those beds, if we closely examine them, will reveal to us 



another feature in their history. 

 They bear undeniable evidence of 

 difference in age. Those which 

 occupy thehigh ground, asatWick- 

 ham Heath, and Greenham Com- 

 mon, are of much older date than 

 the beds which lie in the valley 

 of the Kennet. And the same 

 distinction holds good generally, 

 wherever such superficial deposits 

 are found. The high-level gravels 

 as they have been called, were laid 

 down before the existing valleys 

 were formed. Had not this been 

 so all the hollows would have been 

 filled up with detritus, whilst the 

 higher ground would have been 

 swept bare. But the reverse is 

 the case. We find a thicker layer 

 of gravel on the uplands than in 

 the valleys. Probably at the time 

 of the deposition of the high-level 

 beds, the whole of this neighbour- 

 hood with the exception perhaps, 

 of the highest chalk hills, was a 

 level ocean-bed ; whilst the top 

 of the Hampshire range was an 

 island overlooking a roaring and 

 turbid sea ; and across the valley 

 of the Kennet from Inkpen to 

 Wickham («), a continuous floor 

 of gravel was laid down. 



