MT. 83.] PLATEAU IMPLEMENTS. 385 



effected a considerable amount of excavation. But in our hard 

 and crystalline rocks whole valleys cannot have been thus 

 formed, and all evidence is against it. 



The Chalk and Wealden and Greensand beds of the south of 

 England would no doubt yield much more rapidly to the scour 

 of surging waters. But if the high levels were so scoured, how 

 comes it that the very old weapons were not all washed down 

 into the new valleys? 



Excuse my scepticism. But I want to know exactly the 

 data on which time is calculated as necessary to account for 

 the facts. 



To me the main interest lies in the conclusion that a great 

 marine submergence, comparatively rapid and transient, has 

 taken place since man appeared. I don't care about the 

 number of years ago. But any immense antiquity does not 

 seem to me to be at all proved. Yours very truly, 



AEGYLL. 



J. Prestwich to the Duke of Argyll. 



DARBNT-HULME, SHOREHAM, 14th April 1895. 



DEAR DUKE OF ARGYLL, Pray excuse the delay in my answer 

 to your letter of the 1st instant. On referring to my article in 

 the 'Nineteenth Century,' I fear that I was not sufficiently 

 explicit in limiting my observations to the Kentish area. 



I entirely accept your interpretation of the valleys in Scot- 

 land. They must be of far higher antiquity. My observations 

 were intended to apply to such valleys as those of the Medway, 

 Holmesdale, and in part to that of the Thames. 



The reason why the old implements on the plateau were not 

 all washed down during the re -elevation of the land arose, I 

 think, from the fact that the re - elevation was slow, so that 

 the scour on the high flat table - land was slight ; but when 

 the effluent currents became centred in the narrow intersecting 

 valleys, the rapidity of the current and its scouring became 

 largely increased. 



Nevertheless, portions of the Drift a which contains the 

 plateau implements were denuded and worn; and derived 

 plateau implements are found in the reconstructed Drift I. In 

 this district we have no beds older than a, and no valleys 



2 B 



