Penny Blood: Serial Sensation and Working-Class Entertainment — page 282: what you’re looking at

Machine-transcribed from the original scan — historical spelling and the odd misread are preserved.

cu. xx] DISTRIBUTION OF VOLCANOS. 265 But this great band is not now equally active at every part. In seeking the conditions which produce those disturbances of the crust that determine the regions of present activity, by admitting at intervals of time the elastic fluids from below, we may look to changes in the distributions of load upon the surface, as has been more particularly discussed in the tenth Chapter. It has been there shown, that the less steeply in- clined side of the elevated range will be that on which the principal sedimentation will go on, and, acting as it were on the longer arm of a lever, whose fulcrum is at the centre of gravity of the tract, it will tend to rupture the crust on the margin of the steeper side of the ridge, at the same time causing a certain hang of the tract towards the region of deposit, which will open rather than nip the crust at the place of fracture. We may possibly trace this connection between the situation of the _active regions of the Western American volcanos, and the great rivers of that continent, which deposit their sediment on the eastern side. For imstance, in Central America, we find a comparatively narrow tract, the western side of which is moun- tainous, while on the Eastern the Mississippi deposits vast quantities of sediment. The region of its deposit is known to be a sinking area, and must tend to give a tilting movement to the tract so disturbed, raising and fissuring it along its western border, near which its centre of gravity lies. The very same sedimentation may also be the cause of disturbance, where the West Indian volcanos occur. The wide plain of the Amazon is also an area of great sedimentation, and may have an effect, similar to that just described, upon the coast line adjoming the Andes of Quito. In like manner the deposits from the Rio de la Plata may have a connection with the volcanic series of Chili. Accumulations of snow and ice would have a like effect, and the subsidence of Greenland and the volcanos of Iceland may be possibly due to the accumulation of snow upon the former. These are however speculations which are merely put forward as suggestions. There are other causes which, if the crust be no thicker NOO COLA @ (CO)