Delta chief., 1883-09-26
Volcanic Surprises.

volcanic SuTpFlseSs
For a volcano once supposed to be in
active, Vesuvius has prepared some
lively surprises for the dwellers in its
neighborhood. Its latest surprise has
been to shake upa railroad and destroy
several houses. The people of Hercu-
laneum and Pompeii thought Vesuvius
extinct, till one day it proved in very
| thorough manner that it could still be
reused to activity. Since then no one
has been deceived by its quietude.
Oher volcanoes besides Vesuvius
have from time to time indulged in
what seems to be the general volcanic
propensity of creating surprises. Thus
no one would expect to have mass of
rock of some three thousand cubic feet
suddenly descend upon them from the
sky. But people living nine miles from
Cotopaxi were on one occasion treated
to such a surprise. The CArthngenians,
when they set out against Syracuse,
were not prepared TO cross the fiery
river which to their surprise intercept
ed their march at Mount Etna. They
had no boats with which to cross it.
The great eruption Of Tomboro sur
prised people for some $40 miles around,
the distance at which the force OF the
explosion was heard. They wondered
what was the matter until they learned
of the eruption from one Of the twenty
six persons who were saved, out OF
population OF twelve thousand.
Surprises Of another kind, fearful de-
luges, are the first indications in many
South American districts that volcanoes
whose peaks are in the region Of per-
petual snow have suddenly become &C
tive, the deluge being caused by the
melting Of great masses Of snow.
1t must also be surprise of bcauti-
full though fearful kind to see y fiery
fountain play to the height Of seven
hundred feet from the side o! q mount
ian. Such fountain on Mauna Lon.
in 1852, was a magnificent illustration
Of volcanic fissure, the pressure of lava
Mt the crater being relieved by this new
outlet. The cracks often seen on VOL
canoes. which form dykes radinting
from the center. are created in this
manner. Small extra craters. volca-
noes on volcanoes. which gradually be-
come cone-shapcd. are found along
these assures.
Another surprise. There is no fame
in volcanic eruption, rs is generally re-
presented most graphically in chromos.
The supposititious flames are simply
reflection Of the lava on the cloud of
ashes and cinders. How great . vol
ume Of the latter is elected can be well
understood when II is stated that enough
ashes and cindcrs were elected during
the Tomboro eruption 10 cover all Of
Germany two feet deep.
The islands which have occasionally
surprised the inhabitants along the
coast of the Mediterranean by appear
ing suddenly under their very eyes arc
the results Of volcanic Action. Blu, prob
ably the greatest surprise connected
with this subject Is the formation OF vol
canoes. A volcano is originally nothing
but hole In the ground, formed often
At no elevation by the swelling and
breaking OF an earth bubble. The
mountain which springs up around this
opening Is formed by accumulAtions OF
successive eruptions. The great age Of
volcanoes which. like MAuna Loa and
Mount EtnA, are Il, 600 and 1 1 900 feet
high, can be readily appreciated from
the fact, and from the further fact that
Etna had attained almost its present
height when it WAS observed by Greek
writer's $500 years ago.
'oicnno u IurnAcc on mA&uin-
cent scale, the lava which II elects be-
ing molten rock. The rock IL so
thoroughly fused by some volcanoes
that the lava is NJ thin As honey, and
flows with velocity OF fifteen miles mn
hour. Sometimes 4 is spun out in long
CLASSY threads by the action OF bursting
gas bubbles.
While there are two kinds OF crup-
tions, the quiet and the explosive. there
are many theories regarding the heat
which fuses the rocks into lava Many
think that the interior Of the earth is In
liquid condition, but the better opin-
ion seems to be that the lava occurs In
subterranean lakes. But the theorists
agree that the proximate cause of erup-
tion is the contact Of water with molten
rock.