in june of 1783 a large group of fishers
opened in southern iceland large volumes
of lava soon poured outwards at a rate
exceeding 4 000 cubic meters per second
quickly flooding a large swath of
landscape and a thick layer of molten
rock the fissures soon propagated
further creating a 27 kilometer long
fissure system which was all erupting at
the same time this many flood
basalt-like eruption was the largest
effusive eruption to occur on the planet
in the last 1 000 years sending flows of
basaltic lava up to 70 kilometers
distant other large volume eruptions
have also occurred during the same time
span and almost universally involved
basaltic lava the reason for this is
that the more silica a lava flow has the
more viscous it becomes thus silica rich
lava flows longer than 10 kilometers
such as andesite or rhyolite are highly
unusual and quite rare
take for example the kanagawa volcano
and the aleutian island chain
its lengthy and acidic lobes of lava
travel between 2.44 and 2.65 kilometers
from its summit if this volcano instead
erupted basalt lava flows could have
traveled four times as far
yet in the cascade mountain range there
exists a particular set of two lava
flows which seemingly broke this rule
there from a peak in the goat rocks
wilderness a 74 and 52 kilometer long
andesite to borderline death site lava
flow advanced across the landscape and
what was the planet's longest known
silica rich molten flow of material
these two lava flows are known as the
titan endocyte flows and stretch from
goat rocks all the way to the edge of
yakima the edge of the longer and older
endocyte flow is most pronounced near
cow each creek where the more than 100
foot thick lava flow was cut by a river
forming beautiful outcrops of volcanic
rock
the two massive lava flows were at one
time thought to have originated from
mount rainier by early geologists
instead they originated from a
completely separate volcano known as
goat rocks while this extinct volcano is
still quite tall as it stands at 8 182
feet in height it used to be far higher
at its maximum height this volcano was
taller than mount baker as it stood at
12 000 feet in height it began erupting
3.2 million years ago when the volcano
produced a series of highly explosive
eruptions that deposited large volumes
of rhyolite over a vast area eventually
lava became less silica rich and
eruptive activity switched to producing
basalt over the next one and a half
million years lavas became increasingly
and acidic and a tall strata volcano was
constructed out of grey lava flows near
the end of this period a particular
flank vent near the modern site of bear
creek mountain became particularly
active and for an unknown reason began
producing unusually voluminous flows of
lava
clearly a large magma chamber was at
work underneath the complex and our
options at this particular event had an
unusually low gas and volatile content
and magma in other words eruptions at
this vent were unusually non-explosive
instead of viscoslava fragmenting into
ash during an eruption it instead
produced voluminous lava flows the first
titan in the sight flow erupted 1.64
million years ago it started with a
rapid growth full lava dome as andesite
lava poured out the vent at a rate of
800 cubic meters per second it only took
an hour to overflow a volcanic crater
the several dozen meter tall blocky and
a slight lava loop then began rapidly
flowing towards the northeast at a speed
of several kilometers per hour however
as days turned into weeks and weeks
turned into months the eruptive rate
waned the and the site eventually
reached the titan river as it
represented a low point and had a
downward slope the mass of molten rock
continued down slope while filling much
of the river canyon this process
continued for several years until the
end site turned south at the nashes
river after 12 years of continuous
effusive activity the eruption finally
stopped over the next several hundred
thousand years glacial and water erosion
almost completely removed any trace that
this endocyte flow ever existed once
again opening up the titan river then
1.39 million years ago a similar
eruption occurred from the same source
fent over the span of several years a
similarly voluminous lava flow traveled
along a similar path although since the
river had a different orientation at the
time there were some minor variations it
stopped flowing after having traveled a
stunning 32 miles today large sections
of these massive andesite lava flows
have beautiful polygon columns which can
be seen while driving on us route 12.
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