224 PLINT FLAKES. 



Mr. Wliitley to extend his scale of flint flakes to those of smaller 

 size — such as would require a microscope for their examination, 

 and then contrast the results with the quartz sand from Exmouth, 

 which cuts and polishes granite better than the flint sand from 

 Eastbourne or Eamsgate. From what I have seen, I am of opinion 

 the microscope will shew that the difi'erence between the fracture 

 of flints and that of quartz will be appreciable in particles of the 

 smallest size into which they can be broken or crushed. 



Where, when, and how subsoils were formed, is a question in 

 which the farmer is more interested than the miner; subsoils 

 being the connecting link between the soil on which wheat and 

 turnips are grown, and the bare geological rock in depth. Perhaps 

 it will be scarcely admitted that the subsoil of Mylor Downs, con- 

 taining a bed of quartz, is closely connected with the half-rolled 

 quartz found in the lower ground, from amongst the detrital of 

 which I have seen traces of tin produced by vanning in a shovel. 

 The adjoining, and larger, valley of Carnon has produced a large 

 quantity of tin stuff", and the tin ground extends into Eestronguet 

 Creek. 



This question seems intimately mixed up with what has been 

 called "false bedding" — meaning, by that term, true dejiosits from 

 water in motion, which, on meeting with resistance or mterference 

 with its rate of motion, drops the materials which it carries into 

 irregular beds, in a mode diff'erent from sedimentary deposit in 

 still water, whether of the sea or of lakes. The deposit on a sea 

 beach diff'ers from that resulting from currents of the ocean or of 

 rivers. 



Under these circumstances, we may expect to find the flattened 

 tops or crests of chalk hills to be covered with patches of tertiary 

 rocks containing broken and angular flints, in a mode like that by 

 which, in Cornwall, Mylor and Crousa Downs have been covered 

 with a detrital of crushed quartz. In both cases the steeper sides 

 of the hills would be bare, and in Cornwall they are found crushed 

 downwards ; while the bottoms of the valleys would be filled with 

 flints in the chalk districts, and -with half-worn quartz in Cornwall, 

 under somewhat similar and analogous conditions. There is but 

 one layer of tin-ground on the bare rock, while the valley is filled 

 up with a series of diff'erent strata of common atmosj)heric deposit 

 of detrital, thrown down by water action at different times. In 



