The United States plate and the Pacific plates are two of about a dozen plates that slowly float around the Earth's surface in an underground region known as the Lithosphere. The Lithosphere is moved around by a sea of molten rock beneath Earth's surface known as the Asthenosphere. When two plates collide underground, they produce mountains in a giant slow motion collision. This is dramatically displayed in South Asia where India is slowly mashing into China, producing the Himalayan mountains. This sort of collision is also going on beneath the United States.
The Park has a native population of grizzly bears, moose, grey wolves, and the only wild bison herd on the planet. All these animals live in an active geothermal area where pools of boiling water, mud, and acid make a walk in the fields a dangerous trip.
What makes Yellowstone special is a giant hotspot of magma (melted rock) that reaches up from the Earth's center to within a couple miles of Yellowstone surface. What would normally be underground lakes have become boiling kettles of water erupting out of the ground like a champagne cork. The superheated underground lakes form hot springs, mud pots, fumaroles, and my favorite, the geyser.
Hot springs are basically a natural hot tub. Although you would not want to take a dip in some of these, because they can get as hot as 140 degrees! Hot springs have beautiful colors because of the different chemicals and life forms that live in them. The yellow color is formed from sulfur dioxide which makes hot springs smell like rotten eggs. Hues of red come from iron oxide, the same stuff that forms rust. Hot springs become pink, orange, brown, and green from different bacteria and algae that live in the hot water.
Mud pots are hot springs that do not have enough water to overflow their pool, so the water just stays there boiling away at the rocks surrounding it. Acid within the water works to break down the surrounding minerals from the rocks and all those minerals get mixed into the water to form goopy mud.
Fumaroles are weak geysers that do not have the right plumbing to shoot out streams of water. Instead they vent steam, sometimes letting out a roar.
Every once in a while an unlucky white tailed deer or bison will come floating down the river having fallen into one of these pools of boiling acid.
The bison thrived in the North American plains, at one point numbering over thirty million. When European frontiersmen decided that bison were an unwanted neighbor (they had the annoying habit of knocking down trains in giant herds), it was a not a fun time to be a bison. They were slaughtered by the millions and almost completely wiped out. Before the government took action, the number of bison was down to less than one thousand. Today, they have been successfully protected and there are about 200,000 in the United States. The ones in Yellowstone are the only free herd in the United States; all other bison live on ranches and some are even turned into buffalo jerky and buffalo burgers. Yum!
Please email me at: email@example.com "Yellowstone National Park," Microsoft® Encarta® 98 Encyclopedia.© 1993-1997 Microsoft Corporation. All rights reserved.
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