1824.] below the Chalk, &,t. 367 



lished in The Annals of Philosophy* it would also appear that 

 he is of the same opinion with Mr. Conybeare as to the want 

 of continuity and correspondence of those formations in dif- 

 ferent quarters ; for he states that the siliceous limestone of 

 Hastings had not been noticed in any other place, and describes 

 it as not being coextensive with the rest of the ferruginous 

 sand. 



It is unnecessary to enter further into the history of this sub- 

 ject, as the subjoined list enumerates the principal authors who 

 have published any thing relating to it, and will show the con- 

 nexion of their several arrangements. But I should hardly have 

 ventured to differ from such authorities, if the structure of those 

 tracts in Kent and Sussex which are composed of the beds 

 under consideration were not obscure ; and if, also, it did not 

 appear from Mr. Webster's own account, that the portion of the 

 Isle of Wight to which my observations relate, had compara- 

 tively escaped his notice ;f since it is not possible to examine 

 the country which he has more particularly described, without 

 admiring the fidelity of his observations, and admitting the 

 general soundness of the inferences he has deduced from them. 



. II. The fact is, that there exist, in the Isle of Wight, as in the 

 wealds of Kent and Sussex, — besides the beds of greenish sand- 

 stone immediately beneath the chaik, — two distinct series of 

 sands which differ from each other considerably in composition; 

 and that the features of the surface also correspond with the geo- 

 logical division of the strata, although local circumstances have 

 rendered this connexion less conspicuous in the Isle of Wight 

 than in the wealds of Kent and Sussex. Both of these sands 

 are separated from the beds above them to which Mr. Webster 

 has confined the denomination of green sand, by a stratum of 

 blue clay ; and the two sands themselves are again distinctly- 

 separated by a second stratum of clay, precisely corresponding, 

 both in situation, and in the fossils which it contains, with the 

 weald clay of Kent and Sussex. It is the inferior of these sands 

 alone which is the equivalent of the Hastings beds ; and these 

 constitute the lowest formation visible in the Isle of Wight : 

 the true Purbeck beds not appearing at all upon the coast, nor, 

 I have reason to believe, any where in the interior of the 

 island. 



* July, 1824, seep. 6T of the present volume. 



■j- See Letter, pp. 143, 154. &c. The sources of misconception upon this subject 

 have not improbably been, the confused state of the lower beds at Sandown Bay, where 

 -Mr. Webster began his observations in the Isle of Wight, and the strong resemblance of 

 some of the beds which there occur in the weald clay to the Purbeck limestone ; by these 

 circumstances, Mr. Webster, and, perhaps, subsequent observers, have been misled 

 as to the true relations of the lowest strata of the island, and prevented from examining 

 other parts of the coast where they are better displayed. 



