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A Search for the Mechanism of Earth Movements
Published online by Cambridge University Press: 01 May 2009
Summary
There is reason to suppose that a rise and fall of any part of the earth's surface may be due to anticlines travelling through the crust either (a) at the depth at which isostatic compensation becomes effective, which may be likened to the “surface” on which the crust “floats”, or (6) at a less depth, in a layer which becomes molten through the action of radioactivity.
In the case of (a) the cause would seem to be mountain-building in the crust above and the anticlines are outflows of rock-material: the rise and fall may be about equal: there is also some slight reason to suppose that an oscillation, analogous to that occurring when a buoyant object is thrown into water, with the production of a series of waves of diminishing amplitude, has occurred, but it is not yet clear whether such an oscillation is possible.
In the case of (6) the cause of the anticlines is the collapse of a portion of the crust which squeezes out plastic material below: a small rise is followed by a long, slow fall: a rise in one region is accompanied by a fall in an adjacent region : areas may be raised into domes by collapse of surrounding areas, in which case the central area will be a seat of vulcanicity.
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