The silver star., 1897-04-08
lulCanoes and their Re-
lation 10 Ore Deposits,
From the New Road.

soAiVu ~ Wv ~sFSS~'
From the New Road.
The lecture given by Prof. Arthur
Lakes at the Miners National Bureau
Of Information was listened to by q
large audience. The subject was
Volcanoes and Their Relation to Ore
Deposits The lecture was Illustrated
by charts, making the talk more inter-
csting. Owing to the amount Of valu-
able information given The New Road
prints the same In full, which 10 ~
follows:
Most Of us In our western regions live near
TO Or within sight of some kind of old vol
Ali along the borders of our Rocky Noun.
tains we have lava-capped table lands In
occupied BY lava sheets, and evidences OF
past igneoue activity are ON every SIDE.
where lie molten lava came MU up through
assures In the earth and poured In streams
over the then surface Of the country, or over
eruptions were through assures or openings
that mny have been surmOunted by craters
esss %asssa Sr ioe o Ss wss
the igneous forces below. not having power
to. overcome the great heavy mass Of over:
for their. energies by intruding wedge.like
sheets of molten matter between the bed
n Of the Sr y
Intrusive sheets and thick masses Of buried
stone cisterns. rms Y" When % some ' Of these great
puried masses OF lava have been uncovered
BY e5or%Sus erosion they may co1stitrtss ss
Peaks Elk Mountains, La Plata Mountains
and others In Colorado.
Of actual craters though volcanic dykes,
flows and accolitic sheets and intrusive
iavas abound. These volcanic emanations
and Int al run
poured out on the surface and those which
originally never saw the light Of day, have,
rs an on 20 20 cer
tain portions of our coal beds, changing
part Of our Ignite coal into one Of bitn.
minous and coking character, and even, In
limited areas, into anthracite
DEFINITION OF A VOLCANO.
What Is volcano? In boyish days we
might have answered "a burning mountain,
vomiting forth fire, smoke and brimstone;"
volcano need not be a mountain at all to
start with. In its early days 1t began as
dde Ie m Of SfS%nd an T I'M sGt oe IN aRe
or pond. For it Is not until after it has
erupted for some time that 1t builds around
conical hill or mountain. Again 1t is pot a
burning mountain. as we ordinarily un-
d,dta derstand combustion. ~ Neither l. flame nor
night is but the reflection on the cloud Of
lava In the glowing crater below. And the
"smoke'' Is of wreaths OF steam mingled
with volcanic stones and dust.
than fire vents. Even the fiery looking mol
ten lava is so highly charged with contained
moisture, mol that T. is more like hot porridge
Once more. sulphur or birthstone Is not Pc
culiar TO volcanoes. nor vomited directly
from them like lava. hut is secondary re.
suit of eruption caused by the influence OF
acid gases upon certain kinds Of rock and
from chemical precipitation.
RII A
ERUPTION.
The phenomena explanatory Of an ordl-
nary eruption have been graphically de-
lses 9s Feet soSe Sf
the sea level. Its base Is 5000 feet below
that level. The mountain mass is thus 6:OOO
and shaggy material like the dump Of an iron
furnace At night mysterious glow Of
light is seer seen above the mountain. going and
coming like the fiashlight of lighthouse Mt
sea. The crater IL n circular depression 100
feet below the summit. Before an out
-sarsts wsseths Of ssner ascend from a4euras
Of the assures lava Is seen slowly heaving
up and down. The agitation Increases grad
Is formed, which bursts and n rush Of steam
follows. carrying fragments Of the lava
scum high Into the mir. Every time bubble
dash light. is explained. The great masses
f SSys Ms.s hs M tss ~ By sy rudy
mace Of a locomotive and the yapor from the
engine is lit up. Each bubble OF lava as
o these vP e
vapor-cioud Of so-caIled "smoke" overhang-
ing the mountain.
Cracks, communicating with the earth's In
terior. highly heated matter beneath the sur
MS:h great OF
principal phenomena Of this steam noun.
tain. t.,, The boiling lava e asltated by a
It upwards till It approaches the lips OF the
crater. when vast bubbles are formed, the
sudden bursting Of which produces the erup-
sands Of feet Of rock, water is retained In Its
liquid form IN the molten lava. On relief
other cause t6ls flashes into steam and an
charged lava on reaching the surface. gives
steam, hence The lava 'is ow % a. % rst rstm i,ie S
cooled. the surface scum is fnll Of little
scoria or pumice. II " the lava froth 6oat.
ing on top Of a lava stream.
BIRTH AND EaN REyEtSThNSr vSnGAsS. OF A MOD
How a volcano begins and grows up IL
less than a week before the eyes OF nu.
Bay OF Naples is a conicai hill 40 feet high,
stead e the Monte Suoyc. q New Monntaia.
1898 A. D.. this hill was built up By ma.
terinls elected from n volcanic vent. For
two years previous the country was affected
BY earthquakes, increasing III violence and
frequency, TIL the 10th Of September. 1888,
when n depression was noticed on the nitc
Of the future hill. from which hot water IN.
sued. -Four hours later the ground swelieti
up like nn earth bubble and opened, form
Ing a gaping fssurc full Of. molten matter.
From this large masses Of rock, mingled
with mud and pnmice. were thrown 10 u
vent. formed n great mound. This election
Of materials continued two days aud night
on tho third day q large hill was seen 10
falling fragments; the. elections gradually
nights.
Volcanoes change their shape after dif.
ferent eruptions. After q period Of long
quiet, steam finding the lava stopper hard
TO move, may. blow on tho whole top Of the
mountain and greatly enlarge the original
ter q smaller cone grows. and by successive
eruptions the structure of the mountain be.
comes one Of cone within cone. Lava In 4
crater ., by night appear. white bot but rap.
black. BY day lava stream 10 like mass
Of rough cinders rolling along with q rat.
ting sound. At night tho red incandescent
material appears benenth the lava scum.
,: lows rapidly or very slowly, according