The Minneapolis journal. [volume] (Minneapolis, Minn.) 1888-1939, 1906-04-19
HALL ANALYzES
EARTH TREMORS
So" AUTHORITY ON GEoLnGY
SETS FORTH THE THEORIES.
No Connection Between vesuviuss
Eruption and the San Francisco
Catastrophe, He Says-scientists Mis-
taken About Conditions on the West
Coast of the United States.

HCoincidences, merely condolences,
said Christopher w. Hall, professor Of
geology at the state university, when
his attention was called to the sig
nificant fact that there were volcanic
outbreaks and earthquakes, only a short
time before the San Francisco catastro-
phe, at Vesuvius, Formosa, in the South
seas and the West Indies.
Professor Hall explained that the
theory that these widely separated dis
turbances of the earth's crust are re-
lated to each other is contrary to the
most generally accepted hypothesis as
to the earth IS structure.
"According to the best physicists.
among them Sir William Thompson, -
said Professor Hall, the earth is as
solid as piece of steel. Its mean dem
sity is estimated at 5. The density
of the rocks at its surface is between
| 2.5 and 8, but at its center its esti-
mated density is 16. It is hard to con-
ceive of any general disturbance in as
solid mass as this earth, and the most
accepted geological theory Is that such
disturbances are local and cannot be
traced to any mass of molten or fluid
matter in the earth IS center.
"Lines of Weakness.
ttIt is Established geological
fact that there are certain lines OF
weakness in the earth, places where
the different elements which make up
| the earth have not reached their ulti--
mate adjustment. Such a line Of
weakness is found along the western
coast of the Americas. All along the
Pacific coast there are volcanic cones.
Those in the south are comparatively
recent, while those to the north have
been inactive for about 100000 years.
| "Geologists have generally believed
t<I al loxy fol- .
south of San Francisco, but this catas-
trophe has shown that we were mis-.
taken. The earthquake of yesterday
morning was entirely unforeseen In geo
logical science and may necessltate a
reimbursement of some of our theories
as to the earth g structure
To explain the geological action OF
earthquakes and volcanoes, Professor
Hall referred to the seventh hypothesis
presented by Professor Thomas e.
Chamberlin of the University of Chica-
90 In Chambcrlln aud Salisbury's re-
cent work on geology. This hypothe-
sis is that the earth was and is formed
by the "slow adhesion of meteoroidal
or planetesimal natter and that this
matter is in a process of adjustment un-
der the law of gravitation.
Gases and Pressure.
Under this law the heavier elements,
such as the metals, are drawn toward
the center of the earth while the light
er, such. as oxygen. hydrogen and other
gases, being less attracted, form the
other parts of the sphere. The hetero-
:. geneous material drawn from space to
make up the earth is still in the process
Of adjustment. and while the earth az
whole is we'll organized, there are GER
tain pockets or flaws where lighter ele-
ments, principally gases, are caught I'M
der heavier elements. The tremen..
gases to a high temperature, so high
that they are able at length to make
their way to the surface by fuSng the
rock in their path. making lava
"These gases, and their attendant
lava, are found in the middle zone OF
J the earth, between the homogeneous
central sphere and the loose upper crust,
Flaws in the upper crust direct the
egress of these streams of molten rock
and hot gas, either to the surface. caus.
ing volcanic eruptions, or near enough
to the surface to become cooled.
"This earth is one of the most deli
! cately adjusted things in the uni
verse; said Professor Hall, "and these
awful natural catastrophes are but
slight movements to preserve the prop
er balance. Compared with the per.
fect1on OF the Wnole, Iney amount &c
little, tho they are terrible things fol
| the men who happen to cross their path
Gas to the theory that sun spots at
e feet these earth disturbances, do moi
{ care to say much. It is possible. OF
I course, that, by affecting the amount OF
e heat received from the sun, they may
D Indirectly affect the amount of atmo
spheric pressure over a given area
} When you think that rise of one incl
4 in the barometer means an increased
g pressure of one-half pound to every
Il square inch of surface, you can imag
d inc the tremendous pressure exertet
over an area of hundreds of square
q miles. Changes in barometric pressure
d increasing the stress on one part of thu
S earth S surface and decreasing it OF
! another, might furnish those lines o.
t release for which the volcanic pocket
t in the earth S body seem to be wait
> ing"