The Ohio Democrat. (Logan, O. [Ohio]) 1886-1906, 1886-10-23
CAUSE OF EARrHoUkgs.
Brief Condensation of the Theory Usuaiiy
Accepted by Gsologists.


Accepted by Gsologists.
Major Powell, Director OF the United
States Geological Survey, says the ex-
PLANTATION Of earthquakes, usually ac-
cepted by geologists is something like
this:
The earth's surface is believed to be
formed Of n solid crust of rock of varia-
Bile thicknesses in different regions. This
crusts rests upon material In a more
or less fluid condition, so that it readily
yields to agencies of reformation like
water or molten iron. The reasons for
believing that the interior is in some.
what fluid condition are various. The
most important are:
/. From very many observations
made in mines, artesian wells, etc., it Is
discovered that there is an increase Of
temperature from the surface downward,
and that this increase is so great that q
degree Of heat sufficient to melt all
known rock is reached.
2. BY certain geologic genesis certain
rocks from below are brought to tho
surface in mountain building. and those
rocks show evidence of having been
greatly heated, and even of having been
melted.
8. Molten matter in very large quan.
titles comes up from the interior of the
earth through crcvices and volcanic
vents. Besides these lines OF evidence
there arc many accessory facts which
tell the same story. The interior of
tho earth is constantly DOSING heat in a
variety of ways. A small amount is
probably conducted to the surface and
radiated into space. A large amount of
heat is conveyed from the interior
through the agency of hot springs.
Such springs are found in many por-
tions of the known earth, and in few
districts are very abundant. Through
them much heat is conveyed from the
interior to the surface. which is there
radiated into space. The lavas that are
brought up yield vast stores OF heat, all
of which is lost to the earth through
radiation. The secular cooling which
results from the above causes must
necessarily diminish the magnitude of
the earth, and as it shrinks the solid ex-
terror crust must in some manner yield
SO as to conform to the lesser magnitude
thus produced
The stress produced upon the crust OF
the earth by the shrinking of the interior
is modified by another class of agencies.
The land surface of the earth is washed
by rains and rivers, and in the aggre-
gate large bodies of material are car
r ed away and deposited in the bottoms,
which are gradually filled up, and espe-
cially deposited along the shores of the
sea. The unloading of land areas and
the overlooking of certain water areas,
to large extent, localizes it. Again,
the fluid or plastic material of the in.
terror changes its position beneath the
crust of the earth and portions OF
1t flow out as lava, thus an additional
set of stresses is established. Thus
stresses are established through the
agency of contracting interior
throug Oh loading and unloading at the
surface, and through the flow of in
terror matter to lava beds, where such
matter is poured out upon the surface.
The stresses produced by the various
agencies thus described gradually be-
come so great that at last the crust of
the earth must yield. and earthquakes
are produced. Toledo Blade.