XII. — Notices and Extracts from the Minute-Book of the Geologicat 



Society. 



1. — On the Iron-Sand Formation of Sussex. By Gideon Mantell, Esq. 

 F.R., L., and G. S.S. In a Letter to Dr. Fitton, Secretary of the Geo- 

 logical Society. [Read June 14th^ 1822.] 



Sir., 



A SHORT time since I had the honour of presenting to the Society a series 

 of specimens, illustrative of the physical characters and organic remains of the 

 strata of Tilgate Forest. I now submit to its notice some additional exam- 

 ples of the fossils of those deposits, and beg to offer some further observations 

 on their geological position and relations. 



In my work on the Geology of Sussex, I have mentioned the difficulties 

 which attended the determination of their geognostic position, and the reasons 

 which led me to consider them as related to the Purbeck limestone ; but a 

 more accurate survey of the district in which they occur, made in company 

 with my friend Charles Lyell, Esq., Sec. G.S., &c. has enabled me to ascertain 

 that such an opinion is not tenable, and that these strata may with greater 

 propriety be associated with the subordinate beds of limestone, sandstone, and 

 clay, which, in certain parts of Sussex, alternate in the iron-sand formation. 



In the present state of our knowledge, it may be convenient to separate the 

 strata under consideration into two divisions ; comprising in the first the Ash- 

 burnham limestone, and in the second, the strata of Tilgate Forest, as in the 

 following tabular arrangement. 



, 



fl 





^ 





• 



< 



c 



x: 



. 



n 



^ 





.a 





V 













c« 







tt 







P 







«H 



■ji 





o 



£ 





rt 



o 





CS 



\^ 





Subdivisions. 



1 Beds of argillaceous lime- 

 i stone and shale. . . 



} 



Organic Remains, 



Localities. 



Immense 

 shells 



, . , ") Ashburnham, near Bat. 

 quantities of bivalve f , „ „ 



> tie ; Luson's Green, 



94 



Beds of sandstone and 

 clay f 



Bones of birds, turtles, saurian' 

 animals, fishes ; teeth of cro- 

 codiles, and unknown ani- 

 mals of the lizard tribe ; 

 ferns, fruits, and vegetables, 

 allied to the Cycas and Eu- 

 phorbium ; univalve and bi- 

 valve shells 



s2 



near the Black-boys. 



Hastings, Chailey, Lind- 

 field, Cuckfield, Til- 

 gate and St. Leo- 

 nards Forests; Hor- 

 sham, &c. 



