the Hevolutions 'which have taken place on the Globe. 26 1 



volcanic vents are still in activity, (or more exactly the long 

 cliff' (Jalaise) surmounted or bounded by volcanos which run 

 on a great semicircle of the earth from Chili to the Birman 

 country,) presents the most extensive, the most clearly defined, 

 and as it were the least obliterated feature observable in the 

 present exterior configuration of the globe. 



It has been shown, as Professor Sedgwick justly observes, 

 that pai'oxysms of internal energy, accompanied by the eleva- 

 tion of mountains, and followed by mighty waves desolating 

 whole regions of the earth, were a part of the mechanism of 

 Nature ; and what has happened again and again, from the 

 most ancient up to the most modern periods, may have hap- 

 pened once during the few thousand years that man has been 

 living on its surface. We have therefore taken away all an- 

 terior incredibility from the fact of a recent deluge. 



If the general result of the preceding observaiions be exact, 

 we may briefly express it by saying, that the independence of 

 sedimentary formations is both a consequence and proof of 

 the independence of mountain-systems having different direc- 

 tions. Many traces of interruptions in the series of sedimen- 

 tary deposits are, perhaps, so slight in Europe, only because 

 they correspond with mountain-systems which, like that so 

 strongly marked on the shores of Mozambique and Madagas- 

 car, have not sent any ramifications into our countries. 



But if the number of the surface-revolutions of the globe, 

 and of really distinct mountain-systems be still undetermined, 

 and if the series formed by these successive terms be still im- 

 perfectly known, the observations already made nevertheless 

 circumscribe within certain limits that law, which when they 

 shall be all completely known may be manifested in their suc- 

 cession. From the circumstance of the present heights of 

 Mont Blanc and Mont Rosa, dating only from the later sur- 

 face-revolutions of the globe, it is clear, that whatever defini- 

 tive place other and higher mountains may occupy in the same 

 series, this series will never take that gradually and regularly 

 decreasing form which should lead to the conclusion, that the 

 limit was attained. Nothing will show that pha^nomena the 

 last paroxysms of which have been so violent should not 

 be reproduced. However provisional the succession of terms 

 may be wliich results from the preceding memoir, it is diffi- 

 cult to foresee a modification which should so change its 

 aspect, as to lead to the supposition, that the mineral crust of 

 the globe has lost the property of being successively ridged in 

 various directions. It is didicult to conceive a change which 

 would permit us to assure ourselves that ihc period of tran- 



<iuillity 



