1835.] AND ERUPTIVE FORCES. 



reasons, I believe that the frequent quakings of the earth on this 

 line of coast are caused by the rending of the strata, necessarily 

 consequent on the tension of the land when upraised, and their 

 injection by fluidified rock. This rending and injection would, if 

 repeated often enough (and we know that earthquakes repeatedly 

 affect the same areas in the same manner), form a chain of hills ; 

 and the linear island of S. Mary, which was upraised thrice the 

 height of the neighbouring country, seems to be undergoing this 

 process. I believe that the solid axis of a mountain, differs in its 

 manner of formation from a volcanic hill, only in the molten stone 

 having been repeatedly injected, instead of having been repeatedly 

 ejected. Moreover, I believe that it is impossible to explain the 

 structure of great mountain-chains, such as that of the Cordillera, 

 where the strata, capping the injected axis of plutonic rock, have 

 been thrown on their edges along several parallel and neighbour- 

 ing lines of elevation, except on this view of the rock of the axis 

 having been repeatedly injected, after intervals sufficiently long to 

 allow the upper parts or wedges to cool and become solid; for if 

 the strata had been thrown into their present highly-inclined, 

 vertical, and even inverted positions, by a single blow, the very 

 bowels of the earth would have gushed out; and instead of be- 

 holding abrupt mountain-axes of rock solidified under great pres- 

 sure, deluges of lava would have flowed out at innumerable points 

 on every line of elevation.* 



* For a full account of the volcanic phenomena which accompanied tho 

 earthquake of the 20th, and for the conclusions deducible from them, I 

 must refer to Volume V. of the Geological Transactions. 



