• Steam rises off of the colorful Mammoth Hot Springs Terraces


    National Park ID,MT,WY


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 scientific research in Yellowstone.

Electric Peak and Sepulcher Mountain

Electric Peak and Sepulchur Mountain


Greater Yellowstone Ecosystem

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…
Geology glacial

Cuttoff mountain near Junction Butte


Yellowstone was established as the world's first national park primarily because of its extraordinary geology including hydrothermal (water + heat) features like geysers, hot springs, mudpots and steam vents, and other wonders such as the Grand Canyon of the Yellowstone River. Some of the Earth's most active volcanic, hydrothermal, and earthquake systems make this national park a treasure. 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 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…



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…




Fire is a key factor in shaping the ecology of the Greater Yellowstone Ecosystem. For the first 100 years of the park’s existence, managers extinguished fires to preserve park resources. The 1988 fires marked a change in how the public thought about fire in ecosystems. Today, National Park Service aims to restores fire's role as a natural process as this is feasible. Learn More...


Mammoth Terraces


Other Life Forms: Life in Extreme Heat

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…




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

More Resources from non-NPS Sources

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