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Bison
Photograph by Terry Donnelly/Getty Images
Nomadic grazers, bison roam Yellowstone National Park's grassy plateaus in summer and spend winter near warm thermal pools or in the northern section of the park. The huge animals use their heads like a plow to push snow aside in search of food.
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Great Fountain Geyser
Photograph by Michael Melford
America’s first national park, Yellowstone is home to wildlife from bears to bison and geological stunners such as hot springs and geysers. The Great Fountain Geyser, pictured here, erupts every 9 to 15 hours, shooting water up to 220 feet (67 meters) high.
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Lower Yellowstone Falls
Photograph by Michael S. Lewis
The Lower Falls of the Yellowstone River drop a stunning 308 feet (94 meters) to the canyon floor below—twice as far as Niagara Falls. The Yellowstone begins south of the park, traveling more than 600 miles (965 kilometers) before it empties into the Missouri River in North Dakota. It is the longest undammed river in the continental U.S.
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Grand Prismatic Spring
Photograph by David Mencin, submitted to My Shot
The center of Yellowstone National Park's Grand Prismatic Spring steams at 199° Fahrenheit (93° Celsius), too hot for the multicolored bacteria clustering on the cooler perimeter. But dead center is no dead zone: Billions of organisms called thermophiles flourish in the scalding water.
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Upper Geyser Basin
Photograph by Michael Melford
Yellowstone National Park's mile-long (1.6-kilometer-long) Upper Geyser Basin contains the world's greatest concentration of hot springs and geysers. In the entire park, which spreads out over parts of Wyoming, Idaho, and Montana, there are more than 10,000 hydrothermal features—half of all such features in the world.
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Gray Wolf
Photograph by Richard Seeley, submitted to My Shot
Originally native to the area, gray wolves in Yellowstone were killed off as part of "predator control" practices, and by the 1970s no wolves were known to be living in the park. A controversial reintroduction program has been largely successful, and in 2008 there were at least 124 wolves in 12 packs living in Yellowstone.
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Old Faithful
Photograph by Raymond Gehman
One of Yellowstone's most popular attractions is Old Faithful, a geyser named and celebrated for its steadiness rather than a predictable schedule of eruptions. Not the largest or the most regular of the park's geysers, Old Faithful erupts more frequently, with each blast expelling between 3,700 to 8,400 gallons (14,000 to 32,000 liters) of boiling water.
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Elk
Photograph by Raymond Gehman
Elk are the most abundant large mammals in Yellowstone National Park, numbering some 30,000 in the summer. Paleontological evidence shows that the animals have been living on Yellowstone land for at least a thousand years.
