Visitors come to Death Valley to experience the stark and lonely vastness of the valley; the panorama of rugged canyons and mountains; the pleasures of the dry, moderate winter climate; the challenge of the hot, arid summer; the relief of the cooler mountains; and the reminders of frontier and Native American ways of life. Yet Death Valley National Park's greatest value is as an outdoor natural history museum. It contains fine examples of most of the earth's geological eras and the forces that expose them. Plant and animal species, some of which occur nowhere else in the world, have adapted to the harsh Mojave Desert environment here in remarkable ways. Extremes of climate and geography make it the ultimate showcase of American deserts.