CU.XXIV.] OF'MOUNTAIN-CIIAINS. 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 J, 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 Jouru. of Sci., No. 2, third series, p. 121. 

 J Physical, Besch, der Canarischeu luseln. Berlin, 1825. 



