Yellowstone National Park was declared in March 1872. Two million years of volcanic eruptions have built up the plateau that is known as Yellowstone. The second largest eruption (600 000 years ago) was so intense that the blast left a crater 47 miles across, thus forming the Yellowstone Caldera. This Caldera was sculpted by an ice age 13 000 years ago, and melting glaciers carved it's sloping valleys as they retreated. This extraordinary land of geothermal features, lakes, valleys, canyons, and waterfalls has drawn visitors for many years. Usually the earth's crust is 10 times thicker than it is here, and it's the molton lava (just 2-3 miles underground) that heats the park's landscape as hot springs, geysers, mudpots, and fumaroles. Wildlife is abundant in the park, and bison, elk, deer, antelope, coyotes, wolves, and various types of bears are often observed. The breathtaking beauty of this area, draws millions of visitors each year.