The Washington times., 1902-05-18
FACTS AND THEORIES
observation-disclosures

as evidenced by the great earthquake at
| Charleston, when no volcanic phenomena
| were observed.
These earthquake shocks are connect
ed with the causes that produce volcanic
disturbances. In folded ridges like the
Alleghanies We find no eruptive rocks.
Fractures in Crust.
There seem to be great fractures in the
earth's crust along the line Of volcanic
upheavals. One begins on the western
! coast of South America and extends along
the shore of the Pacific to Alaska, thence
! to the Aleutian Islands and to the East
Indies, the scene Of the greatest volcanic
disturbances that we know today.
Another is found In northern South
America and the islands of the Atlantic.
Vents are afforded by these fractures to
tap off the hot molten lava from the reser-
voirs. Sometimes this comes up in huge
sheets and flows as one mass over the side
Of the crater. Fractures may be Of long
extent or may be small, much like safety
valve. ,akHNAA
Held Solid by Pressure.
"The rock beneath the surface is held
potentially solid by the great pressure
upon it. although It may be very hot.
When the pressure becomes unequal. as by
the sinking of land, an eruption occurs.
The same thing can be seen by squeezing
an orange whose side is rent. When the
pressure is very great at one point the
Juice flows out through the fracture. But
there was no sinking Of land in Marti-
nique or st. Vincent and We look to
another cause for the upheaval-
Enormous clouds of steam are seen at
volcanic eruptions which are like the
action of an effervescent fluid when a
cork is removed from the vessel in which
it is confined. Then there is the explosive
effect which scatters volcanic dust and
large fragments Of rock. Later the flow OF
lava comes, which is comparatively calm
with minor explosions.
Cause of Earthquakes.
The earthquake theory affords an ex- |
PLANTATION Earthquakes usually precede |
volcanic eruptions. The steam which is
pent up in the volcanic reservoirs accum-
ulates behind barrier of rock and breaks
II away, giving rise to earthquake shocks.
This. is repeated periodically until 1t
reaches the surface and the eruption oc-
ours. This is the real explanation Of the
sinking Of rock.
The severity OF an eruption from a
particular volcano depends largely on the
frequency OF its outbreaks. IL the cone Is
long inactive the eruption when it comes
is of tremendous effect. This was the
case with Vesuvius. which now has been |
periodically active since A. D. So. Before
that time 1t is supposed to have had
500 years OF Quiescence, and when the up |
heaval came 1t blew out the whole side of
the mountain. Mont Pelee has been quiet
since 1872 and considerable violence could
have been anticipated frcm its eruption.
Action of Water.
What is the source Of the vapor which
Is kept in high tension in the subter-
ranean lava? II WIS noticed that most
rolcanoes were near the seacoast, ana
hat the water which contains hydro
:hloric acid soaked down to the hot rocks
md produced steam which eventually
Freaks its way through the volcano. Other
yascs such as sulphuretted hydrogen and
'ulphurous anhydr;de were also thought
o be produced by this means. This would
Explain the flames seen In an eruption, |
,ut the light generally seen Is nothing |
,ut the reflection of the white hot lava
IN the volcanic dust. The presence Of the
ones In Mexico and in central Asia.
However. are as far as possible from the
eacoast
"The vapors in the lava, 1t therefore
Gems, have been in them since the lava
rst became n constituent part Of the
arth's composition. The earth. by the .
ebular hypothesis. was once an incan-
escent mass and is now in a state of
The original heat. by an
ther theory. was caused at the time Of
he formation OF the earth as a single | I
lass by the collision OF great comets. the
npaet giving rise to the temperature
'hich was stored up in the earth's in
erior and some of which Is still held.
''Vesuvius was at first a submarine VOL