368 



ISLANDS IN THE EOCENE SEA. 

 Fig. 364. 



[On.. XIX 



Z-r-'X 



Section showing that the Weald had been denuded of chalk before the Lower Eocene strata were 



deposited. 



S. Eelative position of Saffron "Walden. 



G. Chalk-escarpment above Godstone, surmounted by a patch of the Lower Tertiary beds, &'. 

 a. London Clay. &, &'. Lower Tertiaries. " c. Chalk. 



d. Upper Greensand. e. Gault. / Lower Greensand and Wealden. 



x. Point at which the present upper and under surfaces of the chalk, if they were prolonged 

 would converge. 



It is therefore inferred, that, if we prolong southwards the upper and 

 under surfaces of the chalk, along the dotted line in the above section, 

 they would converge at the point x ; therefore, beyond that point, no 

 white chalk existed at the time when the Eocene beds, 6, &', were formed. 

 In other words, the central parts of the Wealden, south of a?, were already 

 bared of their original covering of chalk, or had only some slight patches 

 of that rock scattered over them. 



The island, or islands, in the Eocene sea may be represented in the 

 annexed diagram (fig. 365) ; but doubtless the denudation extended 



Fig. 3G5. 



Sea. 



Sou. 



Island in the Eocene Sea. 

 a. Chalk, Upper Greensand, and Gault. b. Lower Greensand. 



c. Wealden. 



farther in width and depth before the close of the Eocene period, and the 

 waves may have cut into the Lower Greensand, and perhaps in some 

 places into the Wealden strata. 



According to this view the mass of cretaceous and subcretaceous rocks, 

 planed off by the waves and currents in the area between the North and 

 South Downs before the origin of the oldest Eocene beds, may have been 

 as voluminous as the mass removed by denudation since the commence- 

 ment of the Eocene era. 



But the reader may ask, why is it necessary to assume that so much 

 white chalk first extended continuously over the Wealden beds in this 

 part of England, and was then removed ? May we not suppose that land 

 began to exist between the North, and South Downs at a much earlier 

 epoch ; and that the upper Wealden beds rose in the midst of the Creta- 

 ceous Ocean, so as to check the accumulation of white chalk, and limit it 

 to the deeper water of adjoining areas ? This hypothesis has often been 

 advanced, and as often rejected ; for, had there been shoals or dry land 



