1850.] 



PRESTWICH ON THE LOWER TERTIARY STRATA. 



271 



Panopsea intermedia, Sow, Fusus. 



Pectunculus Plumsteadiensis, Sow. Ostrea. 



Cardium, n. sp. a ? Teeth of Lamnae. 

 Astarte ? 



"We now enter upon a tract of country, which is so thickly and 

 uniformly covered by beds of gravel and boulder clay drift, that it is 

 rarely that the smallest section of the tertiary beds is visible. Oc- 

 casionally where the chalk is worked we find a small capping of the 

 sands and mottled clays immediately overlying it ; but taking the line 

 of country by Stanstead, Bishop Stortford, Easton near Dunmow, to 

 Great Yeldham, I have not been able to find a single section of the 

 basement bed of the London clay. 



Between Yeldham and Sudbury in Suffolk, however, in a brick-field 

 on the brow of the hill near the village of Gestingthorpe, there is a 

 small section in which the basement bed of the London clay may, I 

 think, be identified, although the only fossils 1 could find in it were 

 the teeth of the usual species oiLamna. (See fig. 17.) 



Fig. 17. — Section at Gestingthorpe^. 



s. 



a. Boulder clay drift. 



b, London clay; upper part of brown sandy clay, with the com- 

 mon bluish facets, and containing a few small sandy ochreous 

 concretions ; passes down into yellowish sand laminated with 

 greyish clay. No organic remains yet found. 



c. Roimd flint pebbles in sand and clay. 



mon. No other fossils. 



d. Bright yellow sands. 



Teeth of LamncB com- 



The chalk outcrops near the base of the hill at a depth probably 

 not exceeding sixty to eighty feet beneath " c." Continuing over the 

 same irregular hilly district, intersected by narrow and small river- 

 valleys, we pass by Sudbury and Layland to Hadleigh. On a hill 

 one mile E.N.E. of this town, the lower beds of the London clay 

 are worked together with the underlying sands. (See fig. 18.) 



Fig. 18. — Section near Hadleigh. 



^!|liVf-,/."V>;v:-v^^^^ Mixed clay and gravel. 



London clay ; brown clay passing downwards into a 

 -^ dark grey sandy clay, with a few shells and teeth 

 =^ of Lamnoe, 



c. Round flint pebbles in sand and clay, with teeth of 

 LamncBt 



d. Light-coloured sands. 

 The chalk crops out at a short distance below this pit. 



* This section, with two near Hadleigh, and three or four near Ipswich, re- 

 quire further examination. 



VOL. VI. — PART I. X 



