PRESTWICH WOOLWICH AND READING SERIES. 101 



Ostrea tenera, Sow. Crustacea (Cancer ?). 



Hydrobia Parkinson!, Mor. Teeth of Lamna. 



Patella. Scales of Fishes. 



Pectunculus terebratularis, Desk, Flustra. 



Planorbis hemistoma, Sow. Cythere ? 



Pholas. Fragments of wood and imperfect 



Serpula. vegetable impressions. 



Further northward in this district we meet with some better and 

 well-known sections. The lower part of the Woolwich series is here 

 generally formed of pebbly sands, remarkable on account of their 

 variable and peculiar characters. At Loam Pit Hill, Lewisham, the 

 section of which has been given both by Dr. Buckland* and by 

 Conybeare and Phillips f (see PI. I. Diag. C, Loc. sect. 10, and ex- 

 planation of the same), these sands are in greater part ferruginous 

 and 18 feet thick. On the hill between Lewisham and Lee the 

 pebbles, instead of being imbedded in sand, are in a matrix of mot- 

 tled clays, which elsewhere occasionally entirely replace both sands 

 and pebbles. No fossils are found either at Deptford or Lewisham. 

 At Woolwich this portion of the series consists of 1 foot of pebbles 

 in an argillaceous green sand, vsdth about 1 8 feet of a slightly pebbly 

 greenish and ochreous sand above them. In the sand are a few cal- 

 careo-ferruginous concretions, and in these are found casts and im- 

 pressions of the Cyrena cuneiformis and Cerithium variabile. In all 

 these localities this bed, when exposed, is seen to repose upon an eroded 

 surface of the Thanet Sands, but it is more especially to the east of 

 Woolwich that this is apparent. The pebbly sands there come down 

 on the Thanet Sands in great sweeps, as shown in the following 

 section on the North Kent Railway, representing a length of 200 to 

 300 feet and a depth of about 12 to 20. 



Fig. 8. — Section on the Railway East of Woolwich. 

 W. The vertical scale of this section is 100 feet to the inch. 



II. Base of Woolwich and Reading series. iii. Thanet Sands. 



But the clearest and most singular exhibition of this phsenomenon 

 is in a small pit on the left of the road ascending the hill from Plum- 

 stead to Abbey Wood Common, where this pebbly bed has been as 

 it were splashed into the soft and yielding surface of the underlying 

 Thanet Sands. 



Fig. 9. — Abbey Wood CommonX- 





"i'gig^^ J II. Dark pebbly argillaceous green 

 sand. 



III. Light-coloured Thanet Sands. 



* Geol. Trans, vol. iv. p. 287, and PI. 13. f Geology of England and Wales, p. 49. 

 X The last time (May 1853) I visited this spot this section was covered over. 



