28 ON THE REVOLUTIONS OF 



numberless shells will become more and more rare, and finally disap- 

 pear ; we sball reach layers of a different nature, which contain no 

 vestige of a living being. They will, however, show by their crystal- 

 lization and even stratification that they were originally formed in a 

 liquid state ; by their oblique situation, their steepness, that they 

 have been overthrown ; by the manner in which they bury themselves 

 obliquely under the layers of shells, that they were formed before 

 them ; finally, by the elevation with which their jagged and naked 

 tops rise above all these layers of shells, that these summits were al- 

 ready above the level of the waters when these shelly layers were 

 formed. 



Such are those famous primitive or primordial mountains which tra- 

 verse our continents in different directions ; elevated above the clouds, 

 separating the beds of rivers, they hold in their perpetual snows the 

 reservoirs which feed the sources, and in a manner form the skeleton 

 or vast frame-work of the earth. 



From a vast distance the eye perceives by the indentions with which 

 tbeir crests are marked, in the sharp points which form their summits, 

 signs of the violent manner of their formation : far different from 

 those conical mountains, those hills with long broad surfaces, in which 

 the recent mass has remained since the period when it was quietly de- 

 posited by the latest receding of the seas. 



These signs become more manifest in proportion as we contemplate 

 them nearer. 



The valleys have no longer sides with gradual declivities, those pro- 

 jecting angles, intersecting each other, which seem to have been the 

 beds of some ancient currents : they expand and contract without re- 

 gularity ; their waters sometimes spread out into lakes, sometimes are 

 precipitated in torrents, sometimes their rocks, suddenly approximat- 

 ing, form transverse clefts, whence the waters fall in cataracts. The 

 disturbed layers on the one side exposing their edge to the summit, 

 present on the other large and oblique portions of their surface. They 

 do not correspond in height, but that which on the one side forms 

 the peak of the steep height, is buried on fhe other side, and does not 

 reappear. 



However, in the midst of all this disorder, great naturalists have 

 arrived at the conclusion that there is a certain arrangement, and that 

 these immense banks, broken and misplaced as they are, have yet a 

 systematic order, which is nearly the same in all great chains. The 

 granite, they say, of which the greater portion of the summits are 

 composed, the granite which protrudes beyond all, is also the stone 

 which is buried under all others , it is the most ancient of those which 



