"Each additional layer of sediment, while not raising the level of the
sea bottom, buries the first layers just so much the deeper and adds to
their temperature just as does the laying of extra blankets on a bed.
When the first layer has reached a depth of a few thousand feet the
rocks which contain the water of crystalization are subjected to a
terrific heat. This heat generates steam, which is held in a state of
frightful tension in its rocky prison. Wrinklings in the outer crust of
the earth's surface occur, caused by the constant shrinking of the earth
itself and by the contraction of the outer surface as it settles on the
plastic centers underneath. Fissures are caused by these foldings, and
as these fissures reach down into the earth the pressure is removed from
the rocks and the compressed steam in them, being released, explodes
with tremendous force."
This view is, very probably, applicable to many cases, and the
exceedingly fine dust which so often rises from volcanoes has,
doubtless, for one of its causes the sudden and explosive conversion of
water into steam in the interior of ejected lava, thus rending it into
innumerable fragments. But that this is the sole mode of action of water
in volcanic eruptions is very questionable. It certainly does not agree
with the immense volumes at times thrown out, while explosions of
such extreme intensity as that of Krakatoa very strongly lead to the
conclusion that a great mass of water has made its way through newly
opened fissures to the level of molten rock, and exploded into steam
with a suddenness which gave it the rending force of dynamite or the
other powerful chemical explosives.
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