1822.] Geology of the hie of Wight, S^c. 361 



(1.) Bluish clay containing innumerable fossils of the 

 genus potamides, &c . Whole thickness not exposed. 



(2.) Yellowish sand with the lymn&ay paludiiia, and 



planoi'bis 3 feet. 



(3.) Carbonaceous bed 1 



(4.) Yellowish sand with many specimens of pot amides , 



melanopsis, and cydas , 2\ 



(5.) A thin coaly bed. 



(6.) Sandy beds without shells 2 or 3 



Immediately over these was the upper freshwater calcareous 

 rock forming a bold escarpment. 



In the Hampstead Cliff, the argillaceous marl beds of this 

 formation are considerably more than 100 feet thick. They 

 contain a great many fossils in a beautiful state of preservation, 

 among which are five or six species we did not find in any other 

 part of the island. In the upper part of the cliff, not far from the 

 capping of diluvian gravel, there are some thin beds entirely 

 composed of four or five species of shells, which have been dri- 

 ven pell-mell together, and now adhere to each other like masses 

 of Suffolk crag. Even at this great elevation, we found a thia 

 bed filled with a small shell of the genus corhula, resembling that 

 which is figured by Sowerby, t. 209, f. 4. 



From all that has been stated, we conclude, that the whole 

 formation originated in an interruption to the deposition of the 

 beds of calcareous marl occasioned by a marine inundation ; that 

 the lower part of the formation may be considered of decidedly 

 marine origin ; that some of the intermediate beds may have 

 been formed during a partial or interrupted communication with 

 the sea ; and, lastly, that some of the upper beds were deposited 

 in a part of the basin from which the sea was entirely excluded. 

 In a single instance, we found a fragment of a small bone, and a 

 beautiful vertebral joint of a fish in one of the marine beds of 

 Totland Bay. This fact is worth recording, as it had not been 

 remarked before ; but it throws no fight upon the present ques- 

 tion. On the whole, the name of upper marine formation may, 

 perhaps, be conveniently apphed to the whole system of beds 

 between the upper and lower freshivater formations ; though the 

 extended labours of naturalists have proved, since the publication 

 of Mr. Webster's paper, that several of its fossil inhabitants 

 belong to genera which are now only known to exist in fresh^ 

 water. 



There are two other observations in the Annals of Philosophy^ 

 p. 220, which we shall briefly notice ; first, " That the Woolwich 

 beds may be contemporaneous with this upper marine formation, 

 for many of the shells contained in it are species of freshwater 

 genera;" and, secondly, "That the crag on the coasts of Suffolk 

 and Essex bears evident marks of identity with alluvium." In 

 regard to the first of these observations, without stopping to 



