146 On some of the Slrala in the Kc'ighhourhood of London, 



At Fever?ham, over the chalk, Mr. Francis Crow has 

 iliscovcrtd a bed of dark-brown sand, sliohily agglutinated 

 bv a siliceous cement, and intermixed with a small portioi) 

 of clay. In this stratum, which has been hitherto but little 

 explored, he has found in a siliceous state specimens of 

 Strombus pes pelicdiii and a species of Cucullcea, nearly re- 

 scmliling those whieh are met with in the Black-dowii 

 whetstone pits. 



Patches of ]ddstic clay are frequently found over the chalk : 

 some of these arc yellow, and eiTiployed for the common 

 sorts of pottery ; but others arc white, or grayish-white, and 

 are used for liner purposes. The coarser clay is very fre- 

 i]uently met with, nor are the finer kinds of very rare occur- 

 rence. In the Isle of Wight two species of plastic white 

 clay are worked for the purpose of making lobacco-pipes. 

 A similar clay, wl)ich is used for making gallipots, is dug 

 from the banks of the Medway. A fine, light ash-coloured 

 nearly white clay, which is employed in pottery-works, is 

 also dug at Cheam near Epsom in Surry. 



The ui'PER or itlinty Chalk, which is the next older 

 stratum, is extremely thick, forming stupendous cliffs up- 

 wards of six hundred and fifty feet high, on the south- 

 eastern coast of the island. It extends nearly through al- 

 most all that part of the island which lies south of a line 

 supposed to be drawn from Dorchester in the county of 

 Dorset to Flamborough-head in Yorkshire. 



In this stratum there is a great quantity of flint, chiefly 

 in irregularly formed nodules, disposed in layers, which pre- 

 serve a parallelism with each other and with continuous seams 

 of flint, soinetimes not exceeding half an inch in thickness. 

 The chalk contains a fine sand, which may be separated by 

 washing*. 



The fossils of this stratum are for the most part peculiar 

 to it; very few of them being found in any other. They 

 filso appear to agree very closely with those species found in 

 the chalk of France, by Messrs. De France, Cuvier and 

 Brongniart. The number of fossils noticed by these. gen- 

 tlemen amounts to fifty; but they have as yet only parti- 

 cularised, a part of them. These are here compared with 

 what appeared to be the correspondent fossils in the English 

 part of this stratum ; and some others are also pointed oiit, 

 which these genlleiuen have not vet mentioned as being 

 found in the neighbourhood of Paris. 



* The chalk in liie neighbourhood of Paris contains, according to 

 M. Bouillon I-a Grange, magnesia 0-11, and d\ex o ly. 



In 



