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PBOCEEDINGS OP THE GEOLOGICAL SOCIETY. 



[Mar. 6, 



quainted with many details concerning that formation, I wish to 

 bring before the Society an account of its lithological character and 

 of the order of succession that prevails in it. 



As regards this part of England, the Wealden formation has long 

 been divided into three members, namely — 



The " Weald Clay," the " Hastings Sand," and the " Ashburnham 

 Beds." 



The first, the " "Weald Clay," is much the same through all its 

 thickness ; where there is variety in it, it has been well described by 

 Dr. Pitton, Mr. Martin, and Dr. Mantell. The lowest member, the 

 " Ashburnham Beds," which may, perhaps, be classed with the Pur- 

 beck formation, does not appear in that district in which I have more 

 particularly been engaged. I shall therefore say little of these two, 

 and almost confine myself to the " Hastings Sand," and to the north- 

 ern part of the Hastings Sand country, a district, 50 miles long and 

 varying from 3 to 12 or more in width, lying between and in the 

 neighbourhood of the towns of Tenterden, Cranbrook, Tunbridge 

 "Wells, East Grinstead, and Horsham. 



This " Hastings Sand," it is well known, has much clay and a 

 little of other substances interstratified with it ; and something has 

 been done towards finding out the order and character of its divi- 

 sions, especially in certain districts ; but these are small in extent 

 and are separated from one another, no good comparison of the beds 

 in each has been made, and some of the accounts given seem to be con- 

 tradicted by the facts which I have lately observed. I therefore think 

 it well to lay these before you, with my notions as to their bearing 

 on what was before known ; and I believe they will do a good deal 

 towards connecting together the various information you are already 

 in possession of, and clearing up some points on which doubt or con- 

 fusion has been felt. 



It will be best first to repeat as shortly as possible the conclu- 

 sions arrived at by those who have written about these strata. 



Dr. Mantell, who had paid more attention than any one else to the 

 Wealden formation, and who was particularly successful in the dis- 

 covery and the study of its organic remains, gives the following as 

 the succession of beds : — 



Weald Clay, stiff brown and blue clay ; then the Hastings Sand, 

 divided into — 



1. Horsted Sand : light-coloured sand and sandstone. 



2. Tilgate Beds : sand and sandstone, gritstone (calcareous sand- 



stone), and clay or shale. 



3. Worth Sands : white and yellow sand and sandstone. 



The name of No. 1 is taken from a place, which I have not visited, 

 not far from Lewes ; No. 2 is called " Tilgate Beds " from Tilgate 

 Porest, some miles east of Horsham ; No. 3 is named from its occur- 

 rence, according to Mantell, at Worth, near Crawley. In the neigh- 

 bourhood of Hastings, where the best sections are to be seen, Dr. 

 Mantell recognizes the same series of strata as he observed in the 

 more western parts whence he took their names ; and he describes 



