Yellowstone National Park is a U.S. national park located primarily in Wyoming. Yellowstone is known for “Old Faithful,” a geyser that predictably ejects hot water and steam every 35 to 120 minutes. In fact, the park contains about half the world's active geysers, as well as a host of hot springs and steam vents. Yellowstone is a gigantic caldera that sits atop a shallow magma body or “hot spot” that fuels the geysers.

Yellowstone’s first volcanic eruption took place 2.1 million years ago. Scientists believe this eruption ejected 6,000 times more material than the devastating 1980 eruption of Mt. St. Helen’s in Washington State. A second massive eruption created the Yellowstone Caldera 640,000 years ago. This gargantuan feature is 30 miles by 45 miles in size. There have also been smaller-scale eruptions, as well as lava flows that filled in much of the caldera. The most recent lava flow occurred about 70,000 years ago.

Bison at Yellowstone National ParkAlthough a catastrophic eruption is unlikely in the foreseeable future, the Yellowstone Volcano Observatory monitors seismic activity and ground deformation to keep visitors safe. Seismograph stations detected over 3,000 earthquakes in the park in 2010. While most are small, the park experienced an earthquake that hit 4.8 on the Richter Scale in March 2014.

The quakes are reminders that the Yellowstone caldera continues to flex and evolve. In 2004, scientists found that parts of the caldera were rising up to seven centimeters per year, while another section began to subside. Despite Yellowstone’s remarkable geologic activity, scientists don’t expect another cataclysmic eruption for at least 10,000 years.

The park is also the heart of the Greater Yellowstone Ecosystem, which extends for 28,000 square miles. The area is one of the largest nearly intact temperate ecosystems in the world. As a result, Yellowstone is replete with wildlife, including free-ranging herds of bison and elk, as well as wolves and grizzly bears.

While wolves were exterminated in Yellowstone and much of the United States by the early 1900s, the government reintroduced wild wolves from Canada and Montana into the park in the mid-1990s. There are now over 300 of the animals thriving in the Greater Yellowstone Area.

Humans have also lived in the Yellowstone region for more than 11,000 years. While European Americans began exploring the area in the early 1800s, the first organized expedition wasn’t initiated until 1870. Yellowstone was established as America's first national park in 1872. It is widely considered to be the world’s first national park.


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Photo credit: Daniel Mayer, SA 3.0 via Commons