1853,] SHARPE — SANDS AND GRAVELS OF FARRINGDON. 1/7 



Lower green sand. Another cause has contributed to the difficulty 

 of fixing correctly the age of the deposits near Farringdon ; there are 

 in that neighbourhood several patches of ferruginous sand and gravel, 

 vphich though really distinct, have been assumed to be of one forma- 

 tion : their organic remains, thrown together in our lists, have pro- 

 duced a sort of olla 'podrida, which may serve to warn geologists that 

 palseontological evidence, badly marshalled, becomes a most trea- 

 cherous guide. 



In Mr. Austen's memoir " On the Age and Position of the Fossili- 

 ferous Sands and Gravels of Farringdon*," the various deposits above 

 alluded to are well pointed out, and I refer to his memoir for local 

 descriptions, to some of which I have nothing to add, while I am 

 forced to dissent from many of the conclusions accompanying them. 



The deposits in question fall naturally into three classes, differing 

 materially in their mineral character ; they all rest upon the Kim- 

 meridge clay, except near Farringdon, where the Sponge-gravel covers 

 the junction of the Kimmeridge clay and Coral rag, and extends over 

 the latter bed also ; they are independent of each other, and each un- 

 covered by any other deposit ; therefore their position gives very 

 little indication of their age, only informing us that they are all more 

 modern than the Kimmeridge clay : for closer identification, we have 

 only the internal evidence each may afford, which must principally 

 rest on their organic contents ; and where these fail us, the point 

 must be left in doubt. Commencing on the north, these deposits are 

 as follows : — 



1. The sands and sandstone of Badbury Hill and Farringdon 

 Clump. 



2. The gravels containing an abundance of sponges, &c. at Little 

 Coxwell and Fernham. 



3. The dark brown sand and sandy ironstone of the Furze Hill 

 and Cole's Pits. 



4. The yellow sand and sandstone of Alfred's Hill. 



I can add little to Mr. Austen's account of the sands of Badbury 

 Hill and Farringdon Clump ; they clearly belong to one formation ; 

 the mineral character both of the yellow sands and cherty sandstone 

 of both places being exactly the same, and their position being such 

 that if the hollow between them, produced by denudation, were filled 

 up, the beds would about meet. The only traces of fossils which I 

 met with were impressions of ExogijrcB and Terehratidce in the sand- 

 stones of both localities. Mr. Austen mentions some small Bryozoa, 

 and Mr. Cunnington informs me that he has found Terehratula 

 ohlonga in the sand-pit near the top of Badbury Hill. We may 

 conclude that the deposit belongs to the cretaceous series ; but its 

 place in that series must be left for the present in doubt, since the 

 species just named is found both in the Sponge-gravels of Little 

 Coxwell, in the Upper green sand near Warminster, and in the Lower 

 green sand of Hythe and Lockswell Heath. 



The sand and sandstone of Alfred's Hill probably belong to the 



* Quart. Journ. Geol. Soc. vol. vi, p. 4G4. 



