2Q(j PROCEEDINGS OP THE GEOLOGICAL SOCIETY. [May 8. 



rates, they have little in eommoii with the far more even coast that 

 is formed where there is but one kind of rock. 



It was then pointed out that along the present coast the sea is 

 not the only force engaged in the work of destruction, but that it is 

 largely helped by atmospheric agents (the latter acting from above 

 downwards, to detach and hurl down masses of rock, which the 

 former, acting horizontally below, pounds down and sweeps away) ; 

 and it was inferred that the joint action of the two kinds of force 

 had a far greater effect than either alone. 



In conclusion it was argued that as deposits of great thickness 

 (such as the Wealden beds) had been made by rivers, it must be 

 granted that (allowing for waste) still greater masses of rock had 

 been destroyed by streams and by subaerial actions generally. The 

 denuding power of the sea, however, was by no means denied; but 

 it was allowed that as marine deposits much exceed in quantity 

 those of freshwater origin, so the great denudations, the planings- 

 down of vast tracts of which examples are given by unconformities, 

 have been worked out by the action of the sea, but that, on the 

 other hand, the far smaller denudations and comparatively trifling 

 irregularities of the surface (our hills and valleys) have been worn 

 out by the long- continued action of rain, rivers, and ice. 



