LONDON CLAY. 271 



34. Vertebra of a fish. Foss. Hant. fig. 109. 



2. Sandstone, or arenaceous limestone of Bognor. 



The sandstone rocks of Bognor are the ruins of a deposit once very 

 extensive, and which, even within the memory of man, formed a Hne of 

 low cliffs along the coast; at present, a few groups of detached rocks, 

 covered by the sea at high water, are all that remains, and the period is 

 not far distant, when all traces of it wiU be swept away by the encroach- 

 ments of the ocean. The lowermost part of the rocks is a dark grey lime- 

 stone, in some instances passing into sandstone : the upper part is sili- 

 ceous. The Barn rocks between Selsea and Bognor, the Houndgate and 

 Street rocks on the west, and Mixen rocks on the south of Selsea, are por- 

 tions of the same bed. The fossils enclosed in these strata are nearly 

 similar to those which occur in the London clay. 



These beds are decidedly analogous to the Calcaire grossier of Paris ; 

 the correspondence in their geognostic situation, and in the nature of their 

 materials, and organic remains, sufficiently evince their identity*. 



The sandstone is of a grey colour inclining to green ; and varies con- 

 siderably in hardness and composition. The shells are generally white 

 and friable, consisting of a soft calcareous earth, but in a few instances 

 occur in a good state of preservation. To my young friend and pupil 

 Mr. Rollo, (nephew of the late Dr. RoUo, of Woolwich,) I am indebted 

 for the following specimens collected by him in the summer of 1820. 

 Organic Remains of the Bognor Sandstone. 



1. Rostellaria. 



2. Natica similis ? Min. Conch. Tab. v. 



The specimen figured by Mr. Sowerby is from Bognor, and was col- 

 lected by Wm. Borrer, Esq. of Henfield. 



S. Lingula tenuis. ■ Min. Conch. Tab. xix. fig. 3. 



A delicate minute shell, of a lanceolate form, the anterior end trun- 



* Geological Transactions, Vol. ii. p. 208. 



