Fergus County argus. [volume] (Lewistown, Mont.) 1886-1946, 1906-05-04


into the gorge that the Sacramento
river formerly cut across the coast
ranges. This forms the Golden Gate,
and in the broader mountain valley
behind the sea has spread out to form
the bay.
"A further reason for knowing that
the mountains of this region are grow
ing is the frequency of earthquake
shocks in California. Every year
there are from twenty-five to forty
earthquakes recorded in the state. and
not few of these have been felt in
San Francisco itself. For example,
on March 30. 1898. there was shock
which did damage to the extent of
$342, 900 at the Mare Island Navy Yard.
The city is in region of earthquake
frequency. and itself seems to be near
line of movement. Whether the
center of greatest disturbance of the
present shock is in or near the city
cannot yet be told, though the meagre
reports so far received indicate this.
If it is, San Francisco is in danger
of future disasters.
1T is the experience in the study
of earthquakes due to fault move
ment that the slipping may extend
through period of days before the
strain is fully relieved. This was illus
trated in the Yakutat Bay earthquake.
| which lasted seventeen days There
fore it need not be surprising if the
shock yesterday is followed by 9th
ers, but this is not an absolutely GER
tain conclusion. for it is possible that
the single slip completely relieved
the strain for the time
Some day-no one can tell when
the strain will again need relief, and
renewed slipping will occur, and with
it renewed shaking of the crust, the
violence of which will depend upon
the amount of slipping. 1t is a nee
essary result of mountain growth.
J This instance is but one of many
thousands on record and from all ac-
COUNTS dl)dI tlIlIS llOl Olc vi lII3 SItjl-
est magnitude It has attracted our
attention because it happened to be
near a great center of population,
and not far away from habitations,
as was the case with the Yakutat Bay
earthquake. which was scarcely not
iced.
Coming so soon after the eruption
of VeSuVius it is natural to think OF
association between the two phenom
ena. There is, however, no known
geological reason for assOciating tn
Two. They are too far apart, and or
; two separate zones of earthquake fire.
Quency. For these reasons they car
hardly be sympathetic. Biologists
will feel confident, agree that thu
: close relation between the eruption
d of Vesuvius and the San Francisco
"A earthquake from the standpoint o
y time is a mere coincidence. The shoe
5 is but one of many in the history O
$ California. it is one out of many i
e the great circum-Pacific belt of eartl
l. quake even during the present year
one more movement CHANGED to com
h near a great city short time afte
e an eruption of Vesuvius.
= Il am confident also that, barrin
; its occurrence near a city, geologst
Il will agree that the San Francisc
q n IF m a 20 on1
" rock movements which are a necessar
I, result of mountain growth. The re;
It son for the mountain growth, how
2, ever. is not subject upon whic
It agreement would be so general Thi
is not the place to enter into discus
e sion of that subject, and it must SUI
If flee therefore to state a hypothesi
e most generally held by biologists a
D. best supported by the evidence Til
s hypothesis is that the heated earth
e cooling is contracting: that in doin
d this the cold. rigid crust along certai
S lines is being crumpled, placed in
t state of strain, and broken. When tn
S break occurs and a renewed movemeI
d is forced along a previous line
e breaking an earthquake results. TT
n mountain belt which almost complet
J. ly encircles the Pacific is receiviI
the thrust from the shrinking of Il
al EARTH and for that reason it's mou
Sc tains are rising all the way from Il
ut southern Andes to the Boring Sea al
be from the Kurile Islands Tin the Nor
ok Pacitic) to the East Indies. With tt
ne rising melted rock is forced out he
of and there in form of volcanic con,
es. and by their eruptions and by t
to slippings of the rocks along fa
an. planes earthquake shocks are occ
he ring throughout the zone and m
BY always be expected to occur so 10
I'D as the mountains continue to groy
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