Yellowstone is the first and oldest national park in the world and covers 3,472 square miles (8,987 km²), mostly in the northwest corner of Wyoming. The park is famous for its various geysers, hot springs, and other geothermal features and is home to grizzly bears and wolves, and free-ranging herds of bison and elk.Long before any recorded human history in Yellowstone, a massive volcanic eruption spewed an immense volume of ash that covered all of the western U.S., much of the Midwest, northern Mexico and some areas of the eastern Pacific Coast. The eruption dwarfed that of Mt. St. Helens in 1980 and left a huge caldera. Yellowstone typically erupts every 600,000 to 900,000 years with the last event occurring 640,000 years ago. Its eruptions are among the largest known to have ever occurred on Earth, producing drastic climate change in the aftermath. The park was named for the yellow rocks seen in the Grand Canyon of the Yellowstone - a deep gash in the Yellowstone Plateau that was formed by floods during previous ice ages and by river erosion from the Yellowstone River.In 1872, Yellowstone became the first ''National Park'' reserve declared anywhere in the world, by President Ulysses S. Grant. In 1978 it was designated a UNESCO World Heritage List|World Heritage Site by
http://whc.unesco.org/ UNESCO. http://wikitravel.org/en/Yellowstone National Park