1850.] PRESTWICH ON THE LOWER TERTIARY STRATA. 



257 



Fig. 2*. — Section at Clarendon Hill. 



s. 



a, Ochreous flint gravel. 



b. liondon clay ; dark bluish grey sandy clays with nume- 

 rous PanopcscB, OstrecB, and Finnce. 



Cc. Large tabular masses ; composed, some of almost 

 I a pure green sand, and others of a coarse ochreous 



N sand, with a calcareous cement. A few rather 



small round flint pebbles are scattered through 

 L these blocks. 



d. Alternating thin beds of sand and thick beds of 

 mottled clay ; chiefly red. 



The chalk outcrops lower down the hill at a depth apparently of 

 ahout forty to fifty feet beneath "c." 



Organic remains of stratum "c," at Clarendon Hill. 



Buccinum (.' ambiguura, Desk.). 



, n. sp., large and globose. 



Cancellaria Iseviuscula, Desk. 

 Cardiura nitens, Sow. 



, n. sp., a. 



Corbula longirostris, Desk. 

 Cytherea obliqua, Desk. 



ovalis, var. ?, Sow. 



laevigata, var. a ?, Lamk. 



Ditrupa plana, Sow. sp. 

 Fusus tuberosus, Sow. 



, n. sp., witb plain costse. 



, n. sp., large and smooth. 



Natica glaucinoides, Sov). 



Hantoniensis, Pilk. 



Nucula, a small species. 



Ostrea, large undetermined species. 



Pectimculus brevirostris, Sow. 



Plumsteadiensis, Sow. 



Pyrula tricostata. Desk. 

 Pleurotoma comma. Sow. 

 Rostellaria Sowerbyi, Mant. 

 Tellina. 

 Turritella ? 

 Teeth of Lamnae. 

 Carbonized pieces of wood. 



The fossils are extremely abundant, and occur in large blocks of 

 clay and green sand with a calcareous cement. The most common 

 species are the Ditrupa plana, Natica glaucinoides and N. Hanto- 

 niensis, Cytherea obliqua, Pectunculus brevirostris, Rostellaria Sow- 

 erbyi, and Fyrula tricostata. 



It is not my intention to trace this bed any further in Hampshire : 

 I may however observe, that I there know of no other good section 

 of it. I have seen it, but not well exhibited, at Padnell, in Bere 

 Forest, and also on the railway near Fareham. 



Crossing the intervening chalk district to the most westerly ex- 

 tension of the London tertiaries, the first point, where we meet with 

 some uncertain indications, without sections, of the basement bed of 

 the London clay, is, capping the summit of Bagshot Hill between 

 Great Bedwin and Hungerford. It is better exposed between Hunger- 

 ford and Newbury, near the summit of Pebble Hill, one mile south 

 of Kintbury. (See fig. 3.) 



* This and the following sections (figs. 2 to 20) are all drawn upon the same 

 scale ; viz. 1 inch represents a thickness of 20 feet. Section fig. 1 is an exception 

 to the rule. It is the fig. given in the Journal of the Society, vol. iii. p. 362, and 

 is upon a much larger scale. 



u 2 



