52 
BOGNOR ROCKS. 
witliin the memory of man, formed a line of low 
cliffs along the coast ; at present, a few groups of 
detached rocks, covered by tlie sea at high water, 
are all that remain, and the period is not far 
distant, when even these will be swept away by 
the encroachments of the ocean. The lower- 
most part of the rocks is a dark grey limestone, 
in some instances passing into sandstone : the 
upper part is siliceous. The Barn rocks between 
Selsea and Bognor, the Houndgate and Street 
rocks on the west, and Mixen rocks on the south 
of Selsea, are portions of the same bed. The 
fossils enclosed in these strata are similar to those 
which occur in the London clay. 
These beds are decidedly analogous to the 
Calcaire grassier of Paris ; the correspondence in 
their geognostic situation, and in the nature of 
their materials and organic remains, sufficiently 
evinces their identity. 
The sandstone is of a grey colour inclining to 
green ; and varies considerably in hardness and 
composition. The shells are generally white 
and friable, consisting of a soft calcareous earth, 
but they also occur in a good state of preserv- 
ation. 
They consist of various species of the ge- 
nera NautiluSy RostellarWy Lingula, Tnrritella, 
Pyrula, Pinna, Pectunculus, Pholadomya, See., — 
wood perforated by teredines, &c. Sepfaria some- 
times occur with numerous turritellcp, tlie shells 
of the latter being converted into a porcelain-like 
carbonate of lime : polished slabs of this kind are 
