374 WEALD, HOW DENUDED. [Oh. XIX 



rubble and flints, rudely stratified, as are often conspicuous in parts of 

 the Norfolk coast, where they are associated with glacial drift, and 

 were probably of contemporaneous origin. Similar flints and chalk- 

 rubble have been recently traced by Sir Roderick Murchison to Folke- 

 stone and along the face of the cliffs at Dover, where the teeth of the 

 fossil elephant have been detected. 



Mr. Prestwich also has shown that at Sangatte, near Calais, on the 

 coast exactly opposite Dover, a similar water-worn beach, with an 

 incumbent mass of angular flint-breccia, is visible. I have myself 

 visited this spot, and found the deposit strictly analogous to that of 

 Brighton. The fundamental ancient beach has been uplifted more 

 than ten feet above its original level. The flint-pebbles in it have 

 evidently been rounded at the base of an ancient chalk-cliff, the course 

 of which can still be traced inland, nearly parallel with the present 

 shore, but with a space intervening between them of about one-third 

 of a mile in its greatest breadth. 



Of a somewhat older date than the Brighton beach are some large 

 erratic blocks, the greatest number of which are seen at Pagham and 

 Selsea, fifteen miles south of Chichester, consisting of granite and many 

 other rocks which are not of northern origin, but which seem to have 

 been drifted into their present site by coast-ice from Normandy and 

 Brittany. They overlie a Post-pliocene deposit of marine origin. 

 Like the Brighton beach, they help to prove that during the Glacial 

 period a sea-coast bounded the elevated district of the Weald to the 

 south of the present South Downs. 



Professor Ramsay,* and some other able geologists, who fully 

 admit that the denudation of the Wealden area and that of the 

 North and South Downs was mainly effected by the agency of the 

 sea, incline, nevertheless, to the opinion that the great escarpments 

 of the chalk may have been due to pluvial and fluviatile erosion, 

 the sea, when it last retired, having left the secondary strata planed 

 off at one and the same level. But this hypothesis seems to me un- 

 tenable, because, assuming that the last of the submarine areas due 

 to denudation had an even and level surface before it emerged, I 

 cannot imagine that great superficial inequalities would not have 

 been produced by the waves and tides of the sea during the time 

 when the chalk, gault, greensand, and other formations, some com- 

 posed of harder and som'e of softer materials, were raised gradually 

 above the waters^ The scooping out of the great longitudinal valleys 

 must have commenced during such upheaval ; and as to the transverse 

 valleys, if it be true, as Mr. Jukes has suggested, that they originated 

 at a very remote era by fluviatile erosion, when the chalk extended 

 farther towards the central axis of the Wealden than now, still the 

 subsequent deepening of these valleys must have been due in part to 



* See Professor Ramsay's Physical Geology and Geography of Great Britain, 2d 

 ed. : London, 1864. 



