THE EARTH. 23 



e judged, and about two feet in thickness."* These shells are in their 

 natural state, but they are found also petrified, and almost in equal 

 abundancet in all the Alpine rocks, in the Pyrenees, on the hills 

 of France, England, and Flanders. Even in all quarries from whence 

 marble is dug, if the rocks be split perpendicularly downwards, petri- 

 fied 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 continued 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 substance of the colour of marl ; and they them- 

 selves, also, till they were washed, were of the same colour : but when 

 cleaned, they appeared of the colour of bezoar, and of the same polish. 

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

 the fingers." 



In several parts of Asia and Africa, travellers have observed theso 

 shells in great abundance. In the mountains of Castravan, which lie 

 above the city Barut, they quarry out a white stone, every part of which 

 contains petrI5ed fishes in great numbers, and of surprising diversity. 

 They also seem to continue in such preservation, that their fins, scales, 

 and all the minutest distinctions of their make, can be perfectly dis 

 cerned. 



Fro.m all these instances we may conclude, that fossils are very nu- 

 merous ; and, indeed, independent of their situation, they afford no 

 small entertainment to observe them as preserved in the cabinets of the 

 curious. The varieties of their kinds are astonishing. Most of the 

 sea-shells which are known, and many others to which we are entirely 

 strangers, are to be seen either in their natural state, or in various de- 

 grees of petrifaction. || In the place of some we have mere spar, or 

 stone, exactly expressing all the lineaments of animals, as having been 

 wholly formed from them. For it has happened, that the shells dis- 

 solving by very slow degrees, and the matter having nicely and exactly 

 filled all the cavities within, this matter, after the shells have perished, 

 has preserved exactly and regularly the whole print of their internal sur- 

 face. Of these there are various kinds found in our pits ; many of them 

 resembling those of our own shores ; and many others that are only 

 *o be found on the coasts of other countries. There are some shells 

 resembling those that are never stranded upon our coasts,^ but always 

 remain in the deep :** and many more there are which .we can assimi- 

 late with no shells that are known amongst us. But we find not only 

 shells in our pits, but also fishes and corals in great abundance ; to- 

 gether with almost every sort of marine productions. 



* Phi.. Trans, vol. ii. p. 427. t Buffon, vol i. p. 407. J Phil. Trans, p. 42fi 

 } Buffon. vol. i. p. 408. |] Hill, p. 646. 1 Litti lies. ** Pela^ii. 



