• Winter visitors watching geysers erupting


    National Park ID,MT,WY

Nature & Science

Steam rises from numerous geysers and features in the Lower Geyser Basin in Yellowstone National Park.
Yellowstone contains more than 10,000 thermal features. Research on heat-resistant microbes in the park's thermal areas has led to medical, forensic, and commercial uses.

Yellowstone National Park is as wondrous as it is complex. Established primarily to protect geothermal areas that contain about half the world's active geysers, the park also forms the core of the Greater Yellowstone Ecosystem. At 28,000 square miles, it is one of the largest, nearly intact temperate-zone ecosystems on Earth. It preserves a great variety of terrestrial, aquatic, and microbial life. Natural processes operate in an ecological context that has been less subject to human alteration than most others throughout the nation—and throughout the world. This makes the park not only an invaluable natural reserve, but a reservoir of information valuable to humanity.

The pages in our Nature & Science section are intended to help you understand important concepts about Yellowstone's many resources and issues, including geology, hydrothermal features, volcanic and earthquake activity in Yellowstone, scientific research, and wildlife.

Electric Peak and Sepulcher Mountain

Electric Peak and Sepulcher Mountain


Yellowstone was established as the world's first national park primarily because of its extraordinary geysers, hot springs, mudpots and steam vents, and other wonders such as the Grand Canyon of the Yellowstone River. While these mountains and canyons may appear to change very little during our lifetime, they are still highly dynamic and variable. Learn more...
A bald eagle works on cleaning the meat from a trout that it has caught in the slowly thawing lake.

A bald eagle eating a trout.



Yellowstone's abundant and diverse wildlife are as famous as its geysers. There are 67 species of mammals, including 7 species of native ungulates, 2 species of bears, 330 species of birds, 16 species of fish, 4 species of amphibians, and 6 species of reptiles. It is rare that animals and humans can be in such close proximity. In Yellowstone we get to see what animals do in their natural habitat. Learn More…

Pink blossoms of bitterroot plant.


The vegetation communities of Yellowstone include overlapping combinations of species typical of the Rocky Mountains as well as of the Great Plains to the east and the Intermountain region to the west. The exact vegetation community present in any area of the park is the consequence of the underlying geology, ongoing climate change, substrates and soils, and disturbances created by fire, floods, landslides, blowdowns, insect infestations, and the arrival of nonnative plants. Learn More…

Snow-covered Amphitheater Mountain with a blue sky background.

Dramatic snow-covered Amphitheater Mountain.


Environmental Factors

Sizes, boundaries, and descriptions of any ecosystem vary. In general, we say that the Greater Yellowstone Ecosystem consists of 12-22 million acres and 18,750-28,000 square miles. It is located in Wyoming, Montana and Idaho and encompasses state lands, two national parks, portions of five national forests, three national wildlife refuges, Bureau of Land management holdings and private and tribal lands. Learn More…
Steam rises from the white travertine terraces at Mammoth Hot Springs.

Mammoth Terraces


Other Life Forms

The hydrothermal features of Yellowstone are magnificent evidence of Earth's volcanic activity. Amazingly, they are also habitats in which microscopic organisms called thermophiles—"thermo" for heat, "phile" for lover—survive and thrive. Learn More…

Yellowstone Wolf Project staff hiking in Yellowstone National Park's backcountry while on a trip to search wolf GPS collar locations.



In Yellowstone, scientists conduct research ranging from large studies of landscape-level changes affecting the local ecosystem to studies of tiny organisms that have the potential to change the lives of people the world over. Learn more…

Additional Resources

Yellowstone Science-Related Links From Non-NPS Sources

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