Dr. FiTTON on the Strata below the Chalk. 185 



The affinity in mineralogical composition, — indeed in most of the cha- 

 racters except the species of the fossils which they contain, between the 

 strata in this portion of the series in the Isle of Wight, and those above the 

 chalk on the north of the island, is exceedingly striking; though the groups 

 are separated by the entire mass of the green-sands and the chalk. In 

 both we find reddish and variegated sandy marls, of various and similar 

 shades of tea-green, purplish, and grey ; in both, also, beds of sand and of 

 grit*; and in both series, too, is an alternation of beds containing marine 

 fossils, especially Oysters, with strata which abound in Paludina, Cypris, and~ 

 other productions of fresh water. The inferences from these facts are now 

 so obvious, that nothing, it would seem, but the strongest prepossessions 

 in geological theory could so long have kept them out of sight f ; and the 

 proof they furnish of the repeated submersion and re-elevation of the land, is 

 irresistible. 



(95.) On the other hand, there is a very obvious resemblance, in mineralo- 

 gical character, between a great proportion of the deposits, both above and 

 below the chalk in the Isle of Wight, and the reddish and variegated marly 

 sands of the new red sandstone (red marl), of England. Nothing can better 

 prove the insufficiency of mineralogical characters, as a ground of identi- 

 fication in geology, than this close resemblance in the productions of periods 

 60 distant ; while it demonstrates also the permanence and uniformit}^, both 

 of the substances out of which thte strata have been composed, and of the 

 operations which produced their aggregation |. 



Weald Clay. — This stratum is visible on the coast, in one of the sections at Sandovvn Bay, and 

 in both of those on the west of Rocken-End, forming a narrow band of comparatively low and 

 flat ground, — encircling, and, as it were, insulating the Hastings sands, which rise from beneath 

 it into heights of small elevation. In Sandown Bay, the most eastern portion of the clay, which 



* Grit, not in itself distinguishable from that of Hastings, and containing Paludinae, occurs on 

 the north-east coast of the Isle of Wight, near Cowes. See Mr. Webster's " Letters," &c. p. 321 ; 

 — and " Annals of Philosophy," 1824, vol. viii. p. 379. 



•{■ Soon after my examination of this part of the Isle of Wight, I had the pleasure of a visit there 

 from M. Constant Prevost ; and the following passage in one of his letters, written on his return 

 from an excursion to the west of the island, coincides precisely with what is mentioned in the 

 text : — " La succession des couches rappelle tout-a-fait celle de meme nature, que sur une echelle 

 *' moins grande recouvre la craie, ou mieux est posterieure a la craie, a Alum Bay : c'est la meme 

 " disposition generale, le meme assemblage de couleurs, les alternatives de sable et d'argile avec 

 " lignite, les memes septaires, &c. ; tout est analogue dans les deux series, a I'exception des 

 *' fossiles. On pent retrouver une analogic aussi forte entre les argilo-sables (Hastings sands) 

 " inferieurs a la craie, et la grande formation du nouveau gres rouge; les argiles verte, jaune, et 

 " rouge, les gres blancs et bigarres, les conglomerats," &c. 



+ The abundance of the variegated reddish and greenish sandy clays in the upper members of 

 the Wealden group, both here and in Sussex, is such, — and their proportion to the whole so 

 great, that the name of the deposit might very well have been taken from them ; and if the terra 

 Red-marl be retained as a' general denomination, these and the new red sandstone might with 

 some advantage be called the Upper and Lower (or first and second) red marl; which would in- 

 dicate both their mineralogical resemblance, and their relative position in the series. * 



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