406 GEOLOGY OF THE ISLE OF WIGHT. 



III. The Cretaceous Epoch. — The commence- 

 ment of this era was marked by the subsidence of 

 the entire area now occupied by the greensand 

 formation, to a depth sufficient to admit of the 

 accumulation of the deep sea deposits, of which 

 the greater part of the cretaceous beds of England, 

 and of the adjacent portion of the European Con- 

 tinent, consists. The Wealden sediments were 

 submerged to a great depth, and upon them were 

 deposited sands, and argillaceous mud, and calca- 

 reous detritus, teeming with marine exuviae.* 

 But the ocean of the chalk extended far beyond 

 the limits of the Wealden ; it buried beneath its 

 waters a considerable portion of modern Europe, 

 and its waves reached the New World, and covered 

 part of the continent of North America. This 

 ocean swarmed with numerous forms of marine 

 organisms, belonging in a great measure to species 

 and genera unknown in the earlier, and in the 

 later, geological epochs. The interspersions of 

 freshwater deposits containing terrestrial exuviae, 

 though inconsiderable, prove that although the delta 

 of the country of the Iguanodon was submerged 

 in the abyss of the ocean, a group of islands, or a 

 continent, inhabited by that colossal reptile and 

 its contemporaries, and covered with pine-forests, 



• Evidence : Greensand strata at Atherfield, &c. see p. L'23. 



