Yellowstone National Park
With half of the earth’s geothermal features, Yellowstone holds the planet’s most diverse and intact collection of geysers (two-thirds of those found in the world), hot springs, mudpots, and fumaroles.
Its more than 300 geysers make up two-thirds of all those found on earth.
All of these are evidence of the park’s recent volcanic past.
Such geothermal wonders as Old Faithful are evidence of one of the world’s largest active volcanoes. These spectacular features amazed the park’s earliest visitors, and helped lead to the creation of the world’s first national park.
In 1871, Ferdinand Hayden led an expedition that included artist Thomas Moran and photographer William H. Jackson. As a result of their findings, Congress was convinced that the area should be preserved.
In 1872, President Grant signed a bill to create the park.
When present-day Yellowstone was covered by shallow inland seas, ocean sediments built up layer upon layer to form the common sedimentary rocks found in the park – limestone, sandstone, and shale.
Standing in one place in Mammoth, a visitor can see some of the oldest and newest rocks on earth at the same time. Toward the east side of the park, volcanoes ejected silica-rich lava and ash, which mixed with water to form mudflows.
These mudflows surrounded redwoods, sycamores, magnolias, dogwoods, and other trees, preserving the world’s largest petrified forest.
The park’s high elevation and northern latitude also make it a land of deep snows and long winters. When more snow falls in winter than can melt in summer, ice begins to form under the weight of the snow and eventually begins to flow as a glacier.
Although there are no active glaciers in Yellowstone today, such conditions have occurred here intermittently in the past.
Despite myths to the contrary, there is evidence which suggests that Native Americans have lived in the area for over 10,000 years.
Archaeologists have used palynology (the study of plant pollen), geomorphology (the study of past landforms), and paleoethnobotany (the study of past uses of plants) to come to this conclusion.
Visitor vandalism and nearby ground-disturbing activities (utility systems and roads) have a negative effect on geothermal features.
There are several historic backcountry cabins dating from time when the area was patrolled by the army.
See map of the park.
(This page was updated November 2012.)