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, <f the passage from one indepen- 
dent sedimentary formation to another," characterized by a 
considerable difference in " 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. 
' 6thly. 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 
