The Anderson intelligencer. [volume] (Anderson Court House, S.C.) 1860-1914, 1886-09-09
A Scientific Inquiry as to the Quake.

stitution, in writing up the earthquake,
gives an interview with Prof. McGce as
to the probable cause of the recent dis.
aster. The correspondent says:
A scien nti6c inquiry is being made into
the cause of the earthquake by Professor
MCGEE, of the geological survey, with
competent assistants. Professor MCGEE
is rapidly systematizing the information
put in his hands, and to.day gave your
correspondent an interesting talk. His
theory of the earthquake, or rather the
ono which he adopts as working theory,
is at entire variance with the accepted
opinion here, but seems most reasonable.
He says:
at is simply seaward slip. In say.
ing this I assert nothing but state what
appears to be the most intelligent work.
ing theory for physicists"
"What is q seaward slip7"
"It is movement of the coastal plain
towards the sea. Let me say in round
terms that we divide the region this
side of the Appalachian range into two
portions. The granite or gneiss forma-
ton is called the Piedmont escarpment,
and extends from the mountain ranges to
about where Columbia is. The region
this side of that is made up of what we
call fragmental rock, and is called the
coastal plain. The theory is that this
coastal plain has simply slipped seaward
a bit, and the displacement produced the
shock or tremor."
"What caused it to slip
"There is a tendency in that direction.
Imagine a surface slightly inclined with
this coastal plain everything il. A hum
dred miles or 80 out ut sea there is 8
sharp depression. The tendency of the
coastal plain is towards that depression
Were it not for the resistance of friction
this movement would be constant until
the tendency was satisfied. In spite Of
friction, however, the coastal plain
reaches the point where the pressures
overcome the resistance, and then a slip
occurs. This may come from the read.
justments of the earth's surface constant
ly going on, or from the fact that the
great rivers flowing out of the mountain
ranges are continually loading the coastal
plain with the deposits they bring. In
this way the point may be reached, and
doubtlea has been reached, where the
resistance is overcome, and the forward
movement occurs"
elias the seaward tendency been noted
before?"
sob, yes. In the middle States its
work has been recorded for long time
The movement there has been so gradual
that there have been no very violent
shocks. Observations have been less &c
curate and widespread in the South At
lantic States; and less is known of the
movement" ~! ~
aYou have found nothing since com
ing here to break your theory?"
:, "Nothing. may say that everything
is confirmatorys as far as I have gone.
There is absolutely no reason to believe
that volcanism has anything to do with
this earthquake. On the contrary there
is every reason to believe it had not. ]
have heard of nothing that cannot be
explained by the theory Of displacement,
The area of disturbance alone is strong
suggestion in this direction. 1t is per.
haps the largest ever recorded for any
earthquake. Volcanic disturbances are
usually local, while the slip of coastal
plain hundreds of miles in length may
affect half a continent"
~ asked how he explained the twist.
ing of the railroad track in an opposite
direction to the slips?"
Because there is refuent motion oi
the earth, you see chimneys that have
fallen both ways. Suppose" the pro.
fessor continued, taking piece Of bread
and cutting it in two, almost entirely
through, and holding it at an angle ;
''the upper piece of this bread was forced
to slide off the. lower piece. If / had
cut it clear through there would have
been no resistance except the friction,
but as it is joined together at the end,
there is additional resistance in the effort
to tear loose. There is produced O
crinkling, or what we call corrugation.
This resistance would also increase the
reaction which pushes the earth in the
opposite direction from which it had
slipped"
/ asked how he explained the shocks
which still continue at Summervillc.
Suppose you take" he said, "6fty
saucers aud tie an elastic string to them.
Then pull the sauccrs by the string. You
will find the saucers do not follow the
elastic. Pull in steady motion. They
come in jerky, although you pull with a
perfectly steady hand. The jerky motion
is caused by the difference in what is
called starting friction and sliding fric.
tion. The jerks of the saucers, really
their stops and starts, would not be
synchronous:. Each would act inde.
pendently of the other. So with every
part of the coastal plain. In respond
ing to the force that urged it forward, it
went in jerks, or by fits and starts, and
these movements are independent of each
other, and may be more violent or last
longer at one point than another"
"Do you think the general movement
is over?"
~ do. I think the pressure has been
satisfied and that there will be quiet for
perhaps a long geologic period. The ten.
dency to the sea will continue, however,
and the movement will continue, but it
may be inappreciable to the general
public. 1t is probable that no more
trouble will result, and that the slight
shocks now notable here and there are
the subsiding tremors. Perhaps the
movement may be gentle hereafter in the
South Atlantic States, as it has been in
the Middle States.
Some one suggested that the blue mud
elected from the issures and the distinct
sulphurous smell of the water were VOL
canic hints.
mot at ALL" he replied. "In Florida,
notably, and about Charleston also, there
are mineral salts and sulphurets in the
everything beds or fragments of rock.
There are frequent saline and sulphur
springs and wells. This accounts for the
salty or sulphurous taste of the water
elected from unusual depths in this Sec
tion. The blue mud is simply mud which
is found deep down in the earth in this
region. It is about 5000 feet to solid
rock in this region. The enormous com.
posite above the slide rock is the frsg-
mental or coastal plain that has suddenly
been displaced. Imagine such a mass
hundreds of miles in length and breadth,
slipping forward. Calculate the friction
of this mass rs it is forced forward over
the surface of the bed rock. and you can
form an idea of the disturbance it
r,oJ,o, None;dor fhot III; m ovinor m a 90