342 
SUBMERGENCE OF THE WEALDEN. 
we attempt, from these remains, to restore the fomis 
of the extinct monsters of the ancient world. 
The next great change is the subsidence of the 
Wealden into the abyss of that extensive and pro- 
found ocean which deposited the chalk formation. 
Whether this mutation were effected suddenly, or 
by slow degrees ; whether the Wealden subsided 
entire, or were broken up previously to its sub- 
mergence ; or whether, like the Isle of Portland, it 
constituted dry land at some remote period, ante- 
cedently to its being buried beneath the sea, we have 
no data to enable us to decide. The principal lines 
of elevation of the Wealden are clearly referable 
to those movements which up-heaved the chalk and 
incumbent strata : but we may observe, that the 
deeper beds exhibit traces of extensive faults and 
dislocations, which seem to belong to previous 
disruptions, for the fissures and chasms are filled 
up with broken shale, and clay, and sand, the de- 
bris of the Wealden, and contain no intermixture 
whatever of the marine deposits which may be 
supposed to have once covered them. 
The ocean of the chalk appears to have been of 
vast extent ; it buried beneath its waters a con- 
siderable part of Europe ; and, probably, like the 
Atlantic, its waves reached the western world, and 
covered a portion of the continent of North Ame- 
rica.* The nature of the strata, and the organic 
• The occurrence of the remains of the Mososaurm, that extra- 
ordinary reptile of the Macstriclit beds, in the strata of the United 
States, previously mentioned, is a remarkable fact in corroboration of 
such an inference. See Dr. Morton on tlie Faruginmis Sand Formation 
of North America, Svo. 1 vol. with plates. Philadelphia. 1833. 
