206 ENGLISH CHALK DOWNS. 



and gnidiially, a step at a time, the biealcers and 

 the hiiidspriiigs, acting in concert, wore away tlio 

 bridge of intervening land, and hft (he twin clills 

 of Dover and Cap Bhmcnez as the witnesses of 

 tlie great isthmus that once obviated the necessity 

 for the construction of a Cljannel Tunnel. To 

 this day the geological strata answer to one 

 another exactly on either side the Straits ; and at 

 the luirrow point where the Gernuxn Ocean, ad- 

 vancing south westward, at last shook hands with 

 the English Channel, advancing northeastward, 

 the correspondence between the two sets of cliffs 

 on each side of the sea suggests at once the idea 

 of a forcible disruption — a breach effected in a 

 solid continent by the continual assaults of winds 

 and waters. 



Meanwhile the inland mass of chalk, the last 

 relics of which now form the English downs, had 

 been undergoing no less remarkable and interest- 

 ing changes. When the southeast coast was 

 first raised above the level of the sea, the entire 

 layer of white chalk — a solid tliickness of several 

 hundred feet — must have been covered from end 

 to end by the deep deposits of the tertiary ages. 

 In many places — as, for example, in London and 

 in the eastern counties — these later sediments, 

 the muddy or sandy bottom of some forgotten 

 estuary and ocean, still cover the whole surface 

 of the chalk with a thick layer of superimposed 



