Ch. XXIV.] 
OF MOUNTAIN- CHAINS. 
349 
if we could follow the strike of the beds in their submarine pro- 
longation, who shall say that the tilted group might not be 
found to include strata newer than the chalk, the horizontal 
beds older than the Miocene ? 
Supposed instantaneous rise of a mountain-chain, — * Every- 
thing shows, says M. Elie de Beaumont, that the instantaneous 
elevation of the beds of a whole mountain-chain is an event of 
a different order from those which we daily witness*.' 
We observe with pleasure the rejection, by Mr. Conybeare, 
of the hypothesis that the disturbances affecting large geogra- 
phical districts have been produced at one blow, rather than by 
a series of shocks which may have occurred at intervals through 
a long period of ages, and that he contends for the greater 
probability of successive convulsions, on the ground that such 
an hypothesis is most conformable to the only analogy pre- 
sented by actual causes — ' the operations of volcanic forces j 
Modern volcanic lines not parallel. — By that analogy we are 
led to suppose that the lines of convulsion, at former epochs, 
were far from being uniform in direction, for the trains of 
active volcanos are not parallel, as every one is aware who has 
studied Von Buch's masterly survey of the general range of 
volcanic lines over the globe +, and the elevations and subsi- 
dences caused by modern earthquakes, although they may 
sometimes run in parallel lines within limited districts, have not 
been observed to have a common direction in distant and in- 
dependent theatres of volcanic action. 
We do not doubt that in many regions the ridges, troughs, 
and fissures caused by modern earthquakes, are, to a certain 
extent, parallel to each other, but only within a limited range 
of country ; and such appears to have been the case in many 
districts at former eras. The anticlinal lines of the Weald 
Valley, before alluded to, and of the Isle of Wight, may, in 
this manner, have been contemporaneous, that is to say, both 
* Phil. Mag. and Annals, No. 58, new series, p. 243. 
t Phil. Mag. and Journ. of Sci., No. 2, third series, p. 121. 
% Physical. Besch, der Canarischen Inseln. Berlin, 1825. 
