32 HISTORY OP 



though their whole employment had been nothing else. Englan*! 

 is furnished with its beds, which, though not quite so extensive, 

 yet are equally wonderful. " Near Reading, in Berkshire, for 

 many succeeding generations, a continued body of oyster-shell . 

 has been found through the whole circumference of five or six 

 ncres of ground. The foundation of these shells is a hard 

 locky chalk ; and above this chalk, the oyster-shells lie in a bed 

 vt' green sand, upon a level, as nigh as can possibly be judged, 

 and about two feet thickness."' These shells are in their natu- 

 ral state, but they were found also petrified, and almost in equal 

 abundance^ in all the Alpine rocks, in the Pyrenees, on the hills 

 '){ France, England, and Flanders. Even in all quarries from 

 whence marble is dug, if the rocks be split peipendicularly down- 

 wards, petrified shells and other marine substances will be 

 plainly discerned. 



" About a quarter of a mile from the river Medway, in the 

 county of Kent, after the taking off the coping of a piece of 

 ground there, the workmen came to a blue marble, which con- 

 tinued for three feet and a half deep, or more, and then beneath 

 appeared a hard floor, or pavement, composed of petrified shells 

 crowded closely together. This layer was about an inch deep, 

 and several yards over ; and it could be walked upon as upon a 

 beach. These stones, of which it was composed, (the describer 

 supposes them to have always been stones,) were either wreathed 

 as snails, or bivalvular like cockles. The wreathed kinds were 

 about the size of a hazel-nut, and were filled with a stony sub- 

 stance of the colour of marl ; and they themselves, also, till 

 they were washed, were of the same colour ; but when cleaned, 

 tliey appeared of the colour of bezoar, and of the same polish. 

 After boiling in water they became whitish, and left a chalkiness 

 upon the fingers." ' 



In several parts of Asia nd Africa, travellers have observed 

 these shells in great abundance. In the mountains of Castravan, 

 which lie above the city Barut, they quarry out a whita stone, 

 every part of which contains petrified fishes in great numbers, 

 and of surprising diversity. They also seem to continue in such 

 preservation, that their fins, scales, and all the minutest distinc 

 tions of their make, can be perfectly discerned.* 



1 Phil. Trans, vol. ii. p. 427. 2 Biiffou, vol. i. p. 407. 



3 PJul Trans, p. 126. 4 Bufiuu, vol. i. p. UU 



