Page 2 - 2007 DT 12 Issues

Hot Rocks cubic miles in volcanic rock, about 17 the surface. The immense heat of the
times more than Tambora and 2,400 molten rock and the increasing pres-
n April 10 and 11, 1815, on times as much as Mount St. Helen’s. Its sure in the chamber force the overlying
Sumbawa Island in Indonesia, ash cloud reached west to the Califor- crust to bulge upwards until it ruptures
OMount Tambora unleashed nia coast and east into Iowa. No human at the weakest point and a volcano is
what experts believe to be the most has ever seen the likes of it. formed. The type of volcano and the
explosive volcanic eruption in re- The second and smallest eruption, manner in which it erupts is dictated
corded history. When the explosions created the Island Park caldera some by the composition of the magma
finally ceased on July 15 and the skies 1.3 million years ago and was centered and other factors. Once the chamber
cleared, the 13,000-ft vol- empties sufficiently through
cano had lost an estimated eruption, it collapses and a
4,200 ft. in height, leaving caldera is formed. Over time,
a caldera approximately the chamber is replenished,
4 miles in diameter and Photo Courtesy, USGS either wholly from the mantle
3,640 ft. deep. A volume of plume or, as recent research
ash equal to 36 cubic miles by the University of Wiscon-
of rock was spread over sin hints, by recycling the
more than 800 miles. The collapsed caldera roof above
destruction in the wake of it, as well.
the eruption, along with Yellowstone is only the
the ensuing disease and latest stop on the North
famine, ultimately claimed American conveyor belt,
an estimated 117,000 lives which creeps southwestward
in Indonesia alone. The Sheveluch Volcano, Kamchatka, Russia , May 2001 at a few inches per year. For
vast amount of ash and as long as 17 million years,
dust injected into the stratosphere is in western Yellowstone. plate movement over the hot spot has
thought to have triggered the “year The third and final blast that produced a string of six now-buried
without a summer” in 1816 over much formed the Lava Creek caldera erupted calderas across Washington, Oregon,
of the Western Hemisphere. More than about 640,000 years ago, overlapping California, Nevada and Idaho.
200,000 people in Europe perished due the Huckleberry Ridge caldera, its The inconceivably large and
to famine and disease. eastern margin extending 10 miles fur- violent explosions that rocked Yellow-
But as catastrophic as Tambora ther west. Two of the three events, by stone produced staggering pyroclastic
was, it paled in comparison to what themselves, are among the largest erup- flows of ash, pumice and rock frag-
took place in Yellowstone during the tions known to have occurred on earth. ments that consolidated into welded
last 2 million years. Its volcano holds In the simplest of terms, Yellow- tuffs—in some places several miles
the record—so far—for the biggest stone owes its existence to the move- thick—covering thousands of square
blow of all. ment of the North American Plate over miles of Grand Teton and Yellowstone.
The first and largest of three one of only a dozen or so global hot Streaks and thin layers of Yellowstone
caldera-forming eruption events in spots. In isolated parts of the lower ash have been identified as far away as
the Greater Yellowstone Ecosystem mantel, deep vertical plumes of very California, Saskatchewan, Iowa and
occurred about 2.1 million years ago, hot, buoyant “plastic” rock slowly rise the Gulf of Mexico. In addition to the
resulting in the formation of the Huck- through the dense upper mantle. The volume of ash, each of the eruptions
leberry Ridge caldera. Centered in plumes cause the rocks at the base of produced from 67 to over 588 cubic
western Yellowstone Park, it extended the continental plate to melt, producing miles of rhyolite lava.
as far away as Island Park, Idaho. The magma which eventually collects to That the immense Yellowstone
explosion produced a volume of 600 create a magma chamber just beneath Plateau straddling the Continental

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