Yellowstone is the culmination of several million years of exacting natural processes. Born in the fires of thundering volcanoes and sculpted by glacial ice and running water, Yellowstone has evolved into a land of natural wonders. Although thousands of years have passed since the park's violent birth, its thermal features bear testimony that at a comparatively shallow depth beneath us, the fiery heart of the volcanoes still beats. Literally thousands of hot springs dot the thermal basins, gigantic colums of boiling water are hurled hundreds of feet into the air causing the ground to shake, hissing steam vents puncuate the valley floor, and stumps of redwood forests buried by volcanic ash and petrified in an upright position stand out starkly on eroded mountainsides.

More recently, glaciers have reworked the land's surface by smoothing canyons and leaving a myriad of sparkling blue ponds and lakes scattered across the landscape. Mountain streams now carve beautiful canyons and leap over resistant rock ledges in breathtaking cascades and waterfalls.

Geologically, Yellowstone is a young land, with the last of the lava flows burning their way across the surface less than 100,000 years ago. Soil development is shallow and pioneer plants are common. Fire and water, in the form of thermal heat, snow and rain, still dominate the landscape and determine which plants and animals will make up Yellowstone's natural communities.

On a human level, there is evidence of cultural sites dating back 12,000 years. More recent history can be seen in the historic structures and sites that represent the various periods of park administration and visitor facilities development.

Happily, Yellowstone is in no danger of becoming "Disney-fied": 99 percent of the park's 3,400 square miles remain a pristine wilderness.

Indians, Mountain Men and Explorers

The Yellowstone region has most likely been occupied or regularly visited by man since the retreat of the last period of glaciation. Although the harsh winters probably precluded year-round occupancy for prehistoric man, artifacts indicate that the area was visited extensively as a hunting ground. High-quality obsidian from Obsidian Cliff also attracted prehistoric man, who used it in making knives, lance points, arrowheads and ceremonial artifacts. Material from Obsidian Cliff was traded as far east as the Mound Builders of Ohio.

Modern Indians are known to have hunted in and passed through the area. The Bannock Trail was a main Indian thoroughfare used to cross the park to the plains in search of buffalo from about 1838 to 1878. The Bannock, Blackfoot, Flathead, Nez Perce, Utes, Crows, Shosone, Piegans, and Paiutes lived in close proximity to Yellowstone country and are known to have frequented the region. Only one group of Indians, known as the "Sheepeaters," was here from approximately 1800 to 1871.