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Yellowstone: A Supervolcano
Author: Geiger, Beth
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The world's largest volcano may be hidden under the beauty of America's first national park.
Yellowstone has long been known as a special place. Visitors come to see its towering waterfalls, gurgling hot
springs, and gushing geysers. It is also famous for its spectacular wildlife. That's why it became the world's first
national park in 1872. More recently, scientists have learned that there is something hidden under the park—a
supervolcano!
Sizzling Sites
Signs of volcanic activity are scattered throughout the park. Even the names of some of the park's most famous
features show how hot they are. From Sizzling Basin to Steamvalve Spring and from Firehole Valley to Boiling
River, this park is a hot site.
These places live up to their names. Steaming creeks flow. Hot springs boil. Mud pools bubble. Water holes
brim with boiling acid. Hundreds of scorched trees tower over these sites.
Then there are the geysers. More than 300 of these natural water fountains dot the park. That's more than
anywhere else on Earth.
The most famous is Old Faithful. About every 90 minutes, a hissing sound rises from Old Faithful. The noise
grows louder and louder. Then the geyser roars to life. A tower of scalding water blasts skyward. The smell of
rotten eggs fills the air. The smell comes from gases mixed with the spurting water. Then the water and noise
stop. All is calm again.
Making new Land
Volcanic activity made many of the park's natural wonders. For example, high cliffs are almost everywhere.
Many were thrust up when a volcano erupted long ago. Others mark the edges of old lava flows. The hardened
lava that makes up these cliffs is called basalt.
Beautiful lakes dot the park. Wild bears, bison, and elk drink water from these lakes. Many of the lakes fill
ancient volcanic craters.
Yellowstone Lake is the park's largest lake. It flooded part of a huge caldera. That is a volcanic crater. The
caldera formed when the land inside the park suddenly caved in thousands of years ago.
One of the park's most interesting places is a petrified forest. Most visitors have never seen it. It is hidden deep
within the park. Heat and minerals from melted rock turned the trees in this forest to stone.
What is causing all this volcanic activity? No volcanoes rise above the park. So scientists started looking under
the park.
Deep secret
The fuel for the park's hot spots is buried deep beneath Yellowstone's surface. A churning cauldron of melted
rock, or magma, lies under the park.
The magma flows from a layer of Earth called the mantle. It is located just under Earth's crust. The magma
melts some of the rock that makes up the crust under the park. There, it forms a massive magma pool.
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The magma heats everything in the area. Take a geyser, for example. Hot rocks boil water that drips on them.
The water gets hotter and hotter. It rises through cracks in the rocks. Then it bursts through a hole in the
ground. A geyser erupts.
The melted magma is part of one of the world's largest volcanoes. It is so large that geologists, scientists who
study Earth, call it a supervolcano. This volcano is buried beneath the ground.
It has erupted in the past. The most recent eruption happened 640,000 years ago. It ripped the area apart. It
caused part of the park to cave in, forming the caldera.
A Burning Question
The supervolcano is still active. It continues to change the park. The geysers and hot springs may show that it is
even picking up steam. Geologists wonder when it will erupt again.
No one has ever seen a supervolcano erupt. Yet scientists know what the eruption may be like. They say you
don't want to be around when a supervolcano blows its top.
Let's take a look at what might happen. Everyone will know something is up. The explosion will be heard around
the world. Ash will fill the sky. The sun will disappear from sight for months. Temperatures worldwide will drop.
Some plants and animals will die.
Don't worry. None of this will happen without warning. Geologist Jake Lowenstern told the National Geographic
Channel that he knows what to look for. He studies the volcano under Yellowstone.
Before an eruption, magma will start to rise. The rising magma will cause the ground to bulge slightly.
Geologists have placed special equipment around the park. They show that the ground in Yellowstone is not
bulging.
Earthquakes are another sign that a volcano is about to erupt. Yellowstone has earthquakes all the time. Most
are too small to notice. Before an eruption, lots of strong earthquakes will rattle the park. That too is not
happening.
It may take thousands of years or even longer before Yellowstone erupts again. In the meantime, visitors can
enjoy the sizzling sights, sounds, and smells of one of the world's largest volcanoes.
Bibliography
Citation style: APA 6th - American Psychological Association, 6th Edition
Geiger, B. (2006, 03). Yellowstone: A supervolcano. National Geographic Explorer, 5, 4-11. Retrieved from
http://search.proquest.com/docview/203667508?accountid=88561
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