Semi-weekly south Kentuckian. [volume] (Hopkinsville, Ky.) 1883-1889, 1886-12-24
CAUSE OF EARTHQUAKES.
Brief Condensation of the Theory Usually
Accepted by biologists.

Brief Condensation of the Theory Usual,
Accepted by biologists.
Major Powell, Director of the United
States Geological Survey, says the ex
PLANTATION of earthquakes, usually &c
cepted by biologists is something like
this:
The earth's surface is believed to b.
formed of a solid crust of rock of varia
BILE thicknesses in different regions. Thi,
crusts rests upon material in more
or less fluid condition, so that it readily
yields to agencies of de!ormat'o on like
water or molten iron. The reasons fol
believing that the interior is in a some
what fluid condition are various. The
most important are:
l. 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 8
degree of heat sufficient TO melt al
known rock is reached.
2, BY certain geologic genesis certain
rocks from below are brought to the
surface in mountain building, and these
rocks show evidence of having been
greatly heated, and even of having been
melted.
8. Molten matter in very large guam.
titles comes up from the interior of the
earth through crevices and volcanic
vents. Besides these lines of evidence
there are many accessory facts which
tell the same story. The interior OF
the earth is constantly DOSING heat in q
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 n few
districts are very abundant. Through
them much heat is conveyed from the
interior to the surface, which is there
radated 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 VIII
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 yiel
so as to conform to the lesser magnitude
thus produced
The stress produced upon the Gust o.
the earth by the shrinkingof the interior
is modified by another GLASS 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.
cd 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 n large extent, iocalizes it. Again
the fluid or plastic material of the in
terror changes its position beneath thu
crust of the earth and portions Of
It flow out as lava, thus an additional
set of stresses is established. Thu,
stresses are established through the
agency of contracting interior
through loading and unloading at tn.
surface, and through the flow of in
terror matter to lava beds, where suc
matter is poured out upon the surface.
The stresses produced by the variou.
agencies thus descr bed gradually b..
come so great that at last the crust
the earth must yield, and earthquake
are produced. Toledo Bdde.