14 NATURAL HISTORY. 



bounds are not augmented, probably discharge thos 

 extraneous supplies by subterraneous passages. Coun-p 

 tries that have long been inhabited may likewise be 

 easily distinguished from those where the earth ap- 

 pears in a rude state, where the rivers are full of ca- 

 taracts, where the land is either almost overflowed 

 with water, or scorched with drought, and where every- 

 place where a tree can grow is covered with wood. 



In bur examination of the upper stratum of the 

 earth, we find it to be universally the same substance 

 which substance is nothing else than a composition of 

 the decayed parts of animal and vegetable bodies. 

 Penetrating a little deeper, we discover the real earth, 

 beds of sand, lime, stone clay, shells, marble, gravel, 

 chalk, &c. These strata are always parallel to ore 

 another, and of the same thickness throughout. In 

 neighbouring hills, strata of the same materials are 

 uniformly divided by perpendicular fissures. Shells, 

 skeletons of fishes, marine plants, &c. perfectly similar 

 to those of the ocean, are often found in the bowels of 

 the earth, and on the tops of mountains at very great 

 distances from the sea. Petrified shells are found al- 

 most every where in prodigious quantities, not only in- 

 closed in rocks of marble and limestone, in earths and 

 in clays, but incorporated and filled with the very sul - 

 stances in which they are inclosed. Indeed all ir.a:- 

 bles, lime-stones, chalks, marles, chiys, sands, and al- 

 most all terrestrial substances, are full of shells and 

 other spoils of the ocean. 



From these facts, let us try what conclusions can 

 IK drawn. 



The changes which the earth has undergone for the 

 last two or three thousand years, are inconsiderable, 

 when compared with those revolutions, which succeed 



