192 POSITION OF THE WEALDEN BEDS. MINERAL CHARACTERS. 



be marine formations, but the beds of limestone, conglomerate, sand- 

 stone, and clay, that compose the Sussex beds, or Wealden, contain, 

 almost exclusively, the remains of fresh-water animals and terrestrial 

 plants, and that over a surface exposed to observation nearly sixty 

 miles in length, and from fifteen to twenty miles in breadth. The 

 marine beds on which the Wealden rest, must, at a remote period, 

 have been raised, a considerable height above the ocean, and become 

 dry land, having extensive rivers, lakes, or estuaries filled with fresh 

 water, in which the Wealden beds were deposited. Again, at a sub- 

 sequent period, the whole must have sunk deep beneath the surface 

 of the sea, and been covered by a deposition of chalk and other ma- 

 rine strata, a thousand feet or more in thickness. At a more recent 

 epoch, the chalk, with the subjacent beds of Wealden, were raised 

 to their present elevation above the neighbouring sea. However the 

 present quiescent state of the earth may seem opposed to the admis- 

 sion of such great geological changes, we are irresistibly compelled 

 to resort to these changes for a satisfactory solution of existing phe- 

 nomena. 



The relative position of the Wealden beds will be understood from 

 the annexed map. 



The chalk hills of the North and South Downs will be seen sur- 

 rounding the Weald country. Below the chalk is the green sand, 

 marked with waving lines, containing, like the chalk, marine fossils 

 exclusively. The fresh-water formations of Weald clay and Hast- 

 ings' sand and sandstone, rise from under the lower green sand. 

 The Weald clay and Hastings' sand have generally been represented 

 as distinct formations, but in reality the whole of the Wealden is 

 composed of beds of clay, limestone, and sandstone, though in the 

 outer part, marked with dots, the clay predominates. The sand and 

 sandstone predominate in the central parts marked by diagonal lines, 

 extending east and west from beyond Horsham to Hastings. In this 



