The Sea and Its Work 



fantastic forms which sea-cliffs assume may often 

 be explained on this principle: the harder beds, 

 or dykes, of rocks standing out in bold relief when 

 the neighbouring softer rocks have been eaten 

 away. The oldest, and, as a rule, the hardest 

 rocks of Britain are developed in the western and 

 northern parts of the island, and hence the sea 

 acts with less effect upon them than upon the 

 softer rocks in the east and south of England. 

 Even cursory inspection of a map of England and 

 Wales serves to show how the flowing outlines of 

 the chalk coasts of Norfolk, Lincolnshire, and 

 Yorkshire, contrast with the sharp outlines and 

 bold headlands formed by the old rocks of western 

 Cornwall, Pembrokeshire, and Carnarvonshire. 



In the estuary of the Thames, the rocks are 

 comparatively soft, consisting for the most part 

 of sands, clays and chalk. Within the Thames 

 Basin, then, there should be no difficulty in ob- 

 taining evidence of marine waste. Thus Sir C. 

 Lyell has pointed out that the Isle of Sheppey 

 has suffered considerably by the inroads of the 

 sea, fifty acres of land having been lost within 

 the short space of twenty years, though the cliffs 

 there are from sixty to eighty feet in height. 

 Herne Bay, on the Kentish coast, has lost land 

 to such an extent that it no longer retains its 

 shape as a bay. Going yet further out into the 

 estuary of the Thames, we find a notable illustra- 

 tion of marine destruction at Reculver. This 

 was the old Roman station of Regulbium. Not 

 only has the sea entirely destroyed the military 

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