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Signs! A
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Yellowstone
National Park - Heart of the Caldera
Location
of sign - north of Canyon Village before Dunraven Pass in Yellowstone National Park
Photo
taken June 2008
Close-up
view of sign
Wide
view of sign
Text
of sign:
Heart of the Caldera
The
eastern ridgeline is the rim of a huge crater. Here a volcanic eruption
blew cubic miles of glassy material into the atmosphere -
remnants
carried as far as Texas and California - then the crust collapsed, forming a
caldera or basin. Through a catastrophe
600,000
years ago seems unimaginably remote, subsurface activity has been
ongoing. Bare patches in the forest reveal Washburn
Hot
Springs, where superheated water boils up along caldera fracture lines.
The
volcano's energy source lies beneath your feet, centered only ten miles to
the southeast. From the summit of Purple Mountain
or
Mount Washburn you can see not only the extent of the caldera but also
mysterious bulges in the relatively level plateau. The
same
twin magma chambers that fired the eruption are now upwarping or doming,
forecasting future volcanism.
Hot
gases and molten rock erupted through fractures above the magma
chamber.
The area above the blown-out part of the magma chambers collapsed to
form a vast chamber.
There are no trails to Washburn Hot Springs. The ground there
is unstable - geologists have fallen through the crust and
suffered
serious
burns. Sulfuric acid in the area can burn through clothing.
Graphics
on the sign
In addition
to the text there is an inset map of the park noting where the sign is.
There is a graphical description of the formation of
the
caldera. The is also a picture of the skyline noting the location of
the Absaroka Mountains, Grand Canyon of the Yellowstone,
Washburn
Hot Springs, the caldera boundary, Elephant Mountain, Mt. Sheridan, and the
Tetons.
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You
can find more information about the state of Wyoming here.
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