^flr. Web s t e r on the Strata lying over the Chalk, 1 95 



septaria : In these the shells often retain their original pearly lustre. 

 The nautili are particularly fine. 



Boughton hill, between Feversham and Canterbury, consists of 

 the London clay. Still nearer to Feversham fossil shells are found, 

 which are entirely siliceous. They lie loose in a thin bed of greenish 

 siliceous sand that occupies a situation lower than the blue clay, and 

 are separated from the chalk by a thick bed of yellow sand. Mr. 

 Crow has collected here the strombus pes pelecani, a murex, a 

 species of cucullea, and several other bivalves. 



One of the most interesting sections above the chalk is to be seen 

 at Woolwich, near the banks of the Thames. At this place the junc- 

 tion of the chalk with the strata over it is plainly to be seen. Over 

 the chalk is a stratum about 30 feet thick of very fine Vv^hite sand ; 

 and towards the top there is a thin bed of clay. Next succeeds a 

 stratum of about 10 or 12 feet, composed wholly of flint pebbles, 

 which have been worn by water into their present forms, and lie in 

 the utmost confusion piled on each other, having a vast number of 

 fossil shells lodged in the interstices. 



The whole has the appearance of having been at some period , a 

 heap washed up on the sea shore, similar to our modern beaches. 

 The shells are entirely whitened, and having lost their animal matter, 

 are extremely brittle : their species however may be in general ascer- 

 tained, although very few are to be found entire. They have been 

 already described by Mr. Parkinson. 



The bottom of this stratum of pebbles is now about 30 feet above 

 the level of the sea. Over this is a layer of sand with some fer- 

 ruginous masses, and then several thin strata of clay alternating with 

 sand. In this clay are vast numbers of bivalves, locked into each other 

 so close that this must doubtless have been their original bed. 



2 B 2 



