456 



SKETCH TOWARDS A 



than enough, of what we knew before. If I have clone 

 no more, I have at least shown that there are wide 

 fields still unexplored; it will be long yet, before li- 

 mited food will furnish excuses for what it is now doing. 



And now, let any one compare what the preceding 

 System has told, with what it did not know, and could 

 not tell. I should be ashamed of it, could I have done 

 it better: but if its defects are now visible, as I have 

 desired to make them so, it is also easy to see what 

 every system, in every science, must be: being, what 

 I originally said, a view of what is or appears to be 

 known, right or wrong; and no more. 



I need not separate the deposits of Travertine, under 

 whatever mode, from these alluvial rocks. But let it 

 be remembered, that I have proved the indifference and 

 versatility of marine animals with respect to the qua- 

 lity of water ; since this is an important fact in the 

 Theory of the Earth, as that regards Life. 



Rocks are, now, as they have ever been, decomposed 

 and disintegrated by the action of the elements; and I 

 may safely consider their produce as the first among 

 terrestrial alluvia. Being moved through the slow ac- 

 tion of the rains and gravity, they become partially 

 transported, towards vallies, or into them. Th,e depth 

 of such local decomposition is often very great : and in 

 defect of better causes, this is presumed to be a funda- 

 mental source of denudations. The transporting pow- 

 ers of ordinary rains alone, seem insufficient for all but 

 the smaller subsequent effects : especially when the al- 

 luvia themselves are not in the vicinity: but such tor- 

 rents of rain as are conceivable after the revolutions of 

 the globe, together with rivers which have diminished 

 or disappeared, from the degradation of mountains, 

 may also have constituted such a power; as may, fur- 

 ther, oceanic currents, produced by some of the recent 



