86 TOWN GEOLOGY. [in. 



gradual. Not by spasmodic leaps and starts, but 

 slowly and stately, as befits a God of order, of patience, 

 and of strength, have these great deeds been done. 



But we have not yet done with new worlds or new 

 prodigies on our way to London, as any Londoner may 

 ascertain for himself, if he will run out a few miles by 

 rail, and look in any cutting or pit, where the sur- 

 face of the chalk, and the beds which lie on it, are 

 exposed. 



On the chalk lie especially in the Blackheath and 

 Woolwich district sands and clays. And what do 

 they tell us ? 



Of another new world, in which the chalk has been 

 lifted up again, to form gradually, doubtless, and at 

 different points in succession, the shore of a sea. 



But what proof is there of this ? 



The surface of the chalk is not flat and smooth, as 

 it must have been when at the bottom of the sea. It 

 is eaten out into holes and furrows, plainly by the 

 gnawing of the waves ; and on it lie, in many places, 

 large rolled flints out of chalk which has been de- 

 stroyed, beds of shore-shingle, beds of oysters lying 

 as they grew, fresh or brackish water-shells standing 

 as they lived, bits of lignite (fossil wood half turned 

 to coal), and (as in Katesgrove pits at Heading) leaves 

 of trees. Proof enough, one would say, that the chalk 

 had been raised till part of it at least became dry land, 

 and carried vegetation. 



And yet we have not done. There is another world 

 to tell of yet. 



For these beds (known as the Woolwich and 

 Reading beds) dip under that vast bed of London 

 clay, four hundred and more feet thick, which (as I 



