i 824.] below the Chalk, fa. 371 



Mya mandibula.— (Min. Conch. Plate 43.) 

 Corbula pisum?— (Ibid. Plate 209, fig. 4.) 

 A thin shelled bivalve : perhaps a pecten. 

 A very thin shelled ammonite. 

 Scales and bones of a fish. 



The Gault has, in the Isle of Wight, been sometimes con- 

 founded with the weald clay; from which, however, it is distin- 

 guished by several internal characters, and is every where sepa- 

 rated by the stratum next to be described* 



Green Sand. — This term, although objectionable as being- 

 derived from a character, which is not only variable, but in 

 reality does not belong to the greater part of this stratum, — has 

 been adopted so very generally by the geologists of England, 

 that it seems almost necessary to retain it ; — keeping always in 

 view the great occasional variance between the name, and the 

 true character of what it is intended to signify. 



Mr. Webster's description of what he has named ferruginous 

 sands, relates almost exclusively to this stratum; for he has but 

 slightly noticed the inferior (Hastings) sands, and considers the 

 intervening clay as of subordinate importance : with these ex- 

 ceptions, his descriptions are very instructive. 



The upper part of the series is principally distinguished by 

 an abundance of ferruginous matter; some of the beds ap- 

 pearing to consist, in a great measure, of particles of brown 

 hematitic iron ore, the surfaces of which are highly polished, 

 mixed .with a somewhat coarse quartzy sand. These 

 are especially remarkable in the red cliff near Culver, and 

 in the corresponding elevated beds at Compton Chine. Near 

 the top of the formation also, some of the sandy beds are of a 

 very dark colour ; probably from an intimate admixture of car- 

 bonaceous matter, for the specimens become whitish on being 

 heated, without any bituminous smell. 



In the lower portion, calcareous matter occurs in greater 

 quantity ; and though traces of organic bodies, especially of 

 those allied to Alcyonia, occur throughout the formation, it is 



Erincipally from the lower beds that the shells described as 

 elonging to it have been procured ; and these beds also parti- 

 cularly abound in green particles. The characters of the whole 

 series are fully displayed on the shore of Saudown Bay; the fer- 

 ruginous portion appearing in the most striking form at Redcliff, 

 and the lower beds on the shore immediately to the east of 

 Shanklin, between the Chine and the Village of Sandown ; — 

 where among the debris fallen from the vertical cliff specimens 

 may be found of almost every variety of green sand, from a cal- 

 careous rock resembling the Kentish rag, to a stone composed 

 almost exclusively of green particles. The upper and more 

 ferruginous beds correspond, 1 believe, with what is called Car- 

 stone, at Hunstanton, in Norfolk ; and the contrast between the 

 <1 ifferent parts of the formation is conspicuous in various parts of 



2b 2 



