32 NATURAL HISTORY. 



below the level of rivers, is not derived from them. 

 Five or six feet of earth is sufficient to contain water, 

 and to prevent its escape. 



It would not be easy to make an. exact calculation 

 of the quantity of subterraneous wafers that have no 

 apparent issue. Many suppose that it is far greater 

 than all that is upon the surface of the earth. But 

 it is probable that the quantity of subterraneous wa- 

 ters which never appear at the surface, is very incon- 

 siderable ; For, if the number of subterrjmeous rivers 

 were so great, why do we never see any of their 

 mouths break out like springs, on the surface. But 

 rivers likewise produce considerable changes on the 

 surface of the earth ; they carry off the soil ; they 

 wear away the most solid rocks, and sweep off what- 

 ever opposes them. The same effects would result from 

 subterraneous rivers. But no such changes have ever 

 been discovered ; the different strata every where pre- 

 serve their parallel and primitive position. 



From what we have advanced, we may conclude, 

 that the flux and reflux of the ocean have produced 

 all the mountains, valleys, and other inequalities on 

 the surface of the earth ; that currents of the sea 

 have scooped out the valleys elevated the hills, and 

 iestowed on them their corresponding directions ; that 

 the waters of the ocean too, by transporting and de- 

 positing earth, c. have given existence to the par- 

 allel strata ; that the waters from the heavens destroy 

 the effects of the sea, by diminishing the height of the 

 mountains, filling up the vallies, and chosking the 

 mouths of the rivers ; and, by reducing every thing to 

 its former level, they will restore the earth to the sea, 

 , by its natunil operations, will again create nevr 



