<P> Yellowstone National Park spans an area of 3,468.4 square miles (8,983 km), comprising lakes, canyons, rivers and mountain ranges . Yellowstone Lake is one of the largest high - elevation lakes in North America and is centered over the Yellowstone Caldera, the largest supervolcano on the continent . The caldera is considered an active volcano . It has erupted with tremendous force several times in the last two million years . Half of the world's geothermal features are in Yellowstone, fueled by this ongoing volcanism . Lava flows and rocks from volcanic eruptions cover most of the land area of Yellowstone . The park is the centerpiece of the Greater Yellowstone Ecosystem, the largest remaining nearly - intact ecosystem in the Earth's northern temperate zone . In 1978, Yellowstone was named a UNESCO World Heritage Site . </P> <P> Hundreds of species of mammals, birds, fish, and reptiles have been documented, including several that are either endangered or threatened . The vast forests and grasslands also include unique species of plants . Yellowstone Park is the largest and most famous megafauna location in the contiguous United States . Grizzly bears, wolves, and free - ranging herds of bison and elk live in this park . The Yellowstone Park bison herd is the oldest and largest public bison herd in the United States . Forest fires occur in the park each year; in the large forest fires of 1988, nearly one third of the park was burnt . Yellowstone has numerous recreational opportunities, including hiking, camping, boating, fishing and sightseeing . Paved roads provide close access to the major geothermal areas as well as some of the lakes and waterfalls . During the winter, visitors often access the park by way of guided tours that use either snow coaches or snowmobiles . </P> <P> The park contains the headwaters of the Yellowstone River, from which it takes its historical name . Near the end of the 18th century, French trappers named the river Roche Jaune, which is probably a translation of the Hidatsa name Mi tsi a-da - zi ("Yellow Rock River"). Later, American trappers rendered the French name in English as "Yellow Stone". Although it is commonly believed that the river was named for the yellow rocks seen in the Grand Canyon of the Yellowstone, the Native American name source is unclear . </P> <P> The human history of the park begins at least 11,000 years ago when Native Americans began to hunt and fish in the region . During the construction of the post office in Gardiner, Montana, in the 1950s, an obsidian projectile point of Clovis origin was found that dated from approximately 11,000 years ago . These Paleo - Indians, of the Clovis culture, used the significant amounts of obsidian found in the park to make cutting tools and weapons . Arrowheads made of Yellowstone obsidian have been found as far away as the Mississippi Valley, indicating that a regular obsidian trade existed between local tribes and tribes farther east . By the time white explorers first entered the region during the Lewis and Clark Expedition in 1805, they encountered the Nez Perce, Crow, and Shoshone tribes . While passing through present day Montana, the expedition members heard of the Yellowstone region to the south, but they did not investigate it . </P>

Where did yellowstone national park get its name
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