338 RELATIVE ANTIQUITY [Ch. XXIV. 



Theory of M. Elie de Beaumont. 



1st. He supposes * that in the history of the earth there 

 have been long periods of comparative repose, during which 

 the deposition of sedimentary matter has gone on in regular 

 continuity, and there have also been short periods of paroxys- 

 mal violence during which that continuity was broken. 



' 2ndly. At each of these periods of violence or " revolution " 

 in the state of the earth's surface, a great number of mountain- 

 chains have been formed suddenly. 



*3rdly. All the chains thrown up by a particular revolution 

 have one uniform direction, being parallel to each other within 

 a few degrees of the compass, even when situated in remote 

 regions ; but the chains thrown up at different periods have, 

 for the most part, different directions. 



' 4thly. Each " revolution," or, as it is sometimes termed, 

 "frightful convulsion," has coincided in date with another geo- 

 logical phenomenon, namely, te the passage from one indepen- 

 dent sedimentary formation to another," characterized by a 

 considerable difference in (t organic types." 



( 5thly. There has been a recurrence of these paroxysmal 

 movements from the remotest geological periods, and they may 

 still be reproduced, and the repose in which we live may here- 

 after be broken by the sudden upthrow of another system of 

 parallel chains of mountains. 



* Gthly. We may presume that one of these revolutions has 

 occurred within the historical era when the Andes were up- 

 heaved to their present height, for that chain is the best defined 

 and least obliterated feature observable in the present exterior 

 configuration of the globe, and was probably the last elevated. 

 C 7thly. The instantaneous upheaving of great mountain 

 masses must cause a violent agitation in the waters of the sea, 

 and the rise of the Andes may, perhaps, have produced that 

 transient deluge which is noticed among the traditions of so 

 many nations. 



' Lastly. The successive revolutions above mentioned cannot 



