From the intimate and
complicated manner in which the elevatory and eruptive forces were
shown to be connected during this train of phenomena, we may
confidently come to the conclusion that the forces which slowly and
by little starts uplift continents, and those which at successive
periods pour forth volcanic matter from open orifices, are
identical. From many 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 St. 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 neighbouring 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 beholding abrupt mountain-axes of
rock solidified under great pressure, deluges of lava would have
flowed out at innumerable points on every line of elevation.
Pages:
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617