THE CHALK DOWNS. 209 



strata were subjected to those elevatory move- 

 ments which ultimately raised enormous moun- 

 tain-masses of chalk, together with the wealden 

 deposits on which they rest, above the level of the 

 sea, the last formed, uppermost, and of course 

 least coherent beds, would be the first exposed to 

 the action of the waves ; and if the elevation were 

 gradual,* successive layers would be subjected to 

 the same agency, until the fragments of the ancient 

 ocean-bed, now the Downs, were lifted above the 

 reach of further destruction. The drainings of 

 the elevated portions of the soft calcareous rock 

 would then commence, and give rise to streams 

 and rills, by which the surface would be worn 

 into furrows and channels. Funnel-like cavities, 

 and deep and narrow cylindrical and tubular 

 hollows, would be formed by the gyratory action 

 of eddies or whirlpools, induced by opposing 

 currents ; such effects may be observed on the 

 muddy dunes of an estuary during the reces- 

 sion of the tide. The beds of loose and but 

 slightly water-worn flints — the undulated and 

 unbroken contour of the gently swelling hills — 

 and the smooth basin-shaped coombes, and valleys 

 of chalk districts — characters which are strikingly 



* See Mr. Lyell on the elevation and denudation of the wealden districts ; 

 " Elements of Geology," vol. ii. 



