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. The eruption dwarfed that of Mt. St. Helens in 1980 and left a caldera 30 miles wide by 45 miles long.

That climactic event occurred about 640,000 years ago, and was one of many processes that shaped Yellowstone National Park--a region once rumored to be "the place where hell bubbles up." Geothermal wonders, such as Old Faithful, are evidence of one of the world's largest active volcanoes. These spectacular features bemused and befuddled the park's earliest visitors, and helped lead to the creation of the world's first national park.

Fur trappers' fantastic tales of cauldrons of bubbling mud and roaring geysers sending steaming plumes skyward made their way back east. Several expeditions were sent to investigate, opening the West to further exploration and exploitation. In 1871, Ferdinand Hayden led an expedition that included artist Thomas Moran and photographer William H. Jackson. They brought back images that helped convince Congress that the area known as Yellowstone needed to be protected and preserved.

In 1872, President Ulysses S. Grant signed a law declaring that Yellowstone would forever be "dedicated and set apart as a public park or pleasuring ground for the benefit and enjoyment of the people."

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Yosemite National Park embraces a spectacular tract of mountain-and-valley scenery in the Sierra Nevada, which was set aside as a national park in 1890. The park harbors a grand collection of waterfalls, meadows, and forests that include groves of giant sequoias, the world's largest living things.

Highlights of the park include Yosemite Valley, and its high cliffs and waterfalls; Wawona's history center and historic hotel; the Mariposa Grove, which contains hundreds of ancient giant sequoias; Glacier Point's (summer-fall) spectacular view of Yosemite Valley and the high country; Tuolumne Meadows (summer-fall), a large subalpine meadow surrounded by mountain peaks; and Hetch Hetchy, a reservoir in a valley considered a twin of Yosemite Valley.

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Glacier capped mountains, wild Pacific coast and magnificent stands of old-growth forests, including temperate rain forests -- at Olympic National Park, you can find all three. About 95% of the park is designated wilderness, which further protects these diverse and spectacular ecosystems.

Olympic is also known for its biological diversity. Isolated for eons by glacial ice, and later the waters of Puget Sound and the Strait of Juan de Fuca, the Olympic Peninsula has developed its own distinct array of plants and animals. Eight kinds of plants and 15 kinds of animals are found on the peninsula but no where else on Earth.

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