Ch. III.] 
AND TERTIARY STRATA. 
25 
of the subjacent rocks, whatever they may have been, which 
constituted the original bed of the ocean. Now the degrada- 
tion of these lands would commence immediately upon their 
emergence, the waves of the sea undermining the cliffs, and 
torrents flowing from the surface, so that new strata would 
begin to form in different places ; and in proportion as the 
lands increased, these deposits would augment. 
At length by the continued rising and sinking of different 
parts of the bed of the ocean, a number of distinct basins 
would be formed, wherein different kinds of sediment, each 
distinguished by some local character, might accumulate. 
Some of the groups of isles that had first risen would, in 
the course of ages, become the central mountain ranges of con- 
tinents, and different lofty chains might thus be characterized 
by similar rocks of contemporaneous origin, the component 
strata having originated under analogous circumstances in the 
ocean before described. 
Finally, when large tracts of land existed, there would be a 
variety of disconnected gulfs, inland seas, and lakes, each re- 
ceiving the drainage of distinct hydrographical basins, and 
becoming the receptacles of strata distinguished by marked 
peculiarities of mineral composition. The organic remains 
would also be more varied, for in one locality freshwater species 
would be imbedded, as in deposits now forming in the lakes of 
Switzerland and the north of Italy; in another, marine species, 
as in the Aral and Caspian ; in a third region, gulfs of brackish 
water would be converted into land, like those of Bothnia and 
Finland in the Baltic ; in a fourth, there might be great fluvi- 
atile and marine formations along the borders of a chain of 
inland seas, like the deltas now growing at the mouths of the 
Don, Danube, Nile, Po, and Rhone, along the shores of the 
Azof, Euxine, and Mediterranean. These deposits would 
each partake more or less of the peculiar mineral character of 
adjoining lands, the degradation of which would supply sedi- 
ment to the different rivers. 
Now if such be, in a great measure, the distinction between 
