UPPER, OR FLINTY CHALK. 151 



of their destruction. This he supposed might have been occasioned by 

 some sudden shock or convulsion, " which in an instant shivered the 

 flints, though their resistance stopped the incipient motion ; for the flints 

 though crushed are not displaced, vrhich must have been the case, had 

 the beds slid sensibly *." 



Off'ham pit, is nearly two hundred feet high, and exhibits a good 

 section of the Sussex chalk. It contains the large fibrous bivalve, the 

 fragments of which are so frequently met with in every locality ; teeth 

 and palates of fishes, and numerous zoophytes. It is the only locahty 

 near Lewes, in which the Marstipites have been discovered. South of 

 this place, in a bank on the road-side, the chalk is covered by a bed of 

 ochraceous clay, and where in contact with the latter, the chalk and flints 

 are marked with regular stripes of yeUow, bluish grey, and brown. This 

 singular appearance extends into the substance of the chalk, but does not 

 penetrate beyond the external crust of the flints : similar specimens some- 

 times occur in the pit in South-street. 



Clayton pit. This locality produces Inocerami, Nautili, Plagiostomse, 

 Terebratulae, Marsupites, &c. 



Falmer. An excavation made on the side of the road, leading from 

 the village, towards the farm of Mr. Moon, is particularly interesting 

 from the evident proofs it exhibits of the changes the strata have suffered, 

 since their original deposition. The pit is about twenty feet high, and 

 contains the following beds; beginning with the lowermost. 



1. Chalk with horizontal layers of large flints, - 6 feet. 



2. Chalk much broken, containing interspersed flints, 10 feet. 



3. Ochraceous clay and flint pebbles from 2 to 4 feet. 

 From the upper part of the pit, several fissures of an irregular shape, 



and from three to six feet in diameter, extend through the broken chalk 

 to the more solid beds beneath. Some of these cavities are of an inversely 

 conical form, and others are nearly cyhndrical. They are fiUed with 

 ochraceous clay, rolled flints, and rounded masses of a conglomerate, con- 



* Li7inean Transactions, Vol. vi, p. 108. 



