Yellowstone Volcano Caldera

Much of Yellowstone sits inside an ancient volcanic caldera (the exploded crater of a volcano). The last major caldera forming eruption occurred 600,000 years ago.

Overview

Calderas are large basin-shaped volcanic depressions more or less circular in form. Caldera eruptions on the Yellowstone scale have a worldwide frequency of perhaps once every hundred thousand years.

The volume of volcanic rock produced by the first Yellowstone caldera eruption was about 600 cubic miles, 2,400 times as much as Mount St. Helen's. Yellowstone ash is found in Ventura, California to the west and in Iowa to the east.

After the initial eruptions, the magna chamber formed by the volcanic eruption began to empty, large sections of the foundering magma chamber roof collapsed along the ring fractures, triggering a chain reaction that produced a caldera 45 miles long and 28 miles wide.

Thus, in one brief "moment" of geologic time there was launched an incredible chain of events, which led to the creation of many of the natural wonders of Yellowstone National Park.

Heat from the enormous reservoir of molten rock remains deep within the earth beneath Yellowstone, sustaining the spectacular phenomena for which the Park is so famous.

The formation of the caldera and the eruption of lavas profoundly influenced the shape of the present-day landscape. Once a land covered almost entirely by mountains, the part that collapsed, nearly one third of the total Park area, is now characterized by low rolling plateaus formed from the thick lava flows that filled the caldera.

The carving of the spectacular Grand Canyon of the Yellowstone and the creation of the large interior basin now occupied by beautiful Yellowstone Lake are also closely related to this volcanic event.

Hikes and Attractions

The surrounding rim of the ancient Yellowstone caldera is composed of many mountains rising to over 9,000 feet, and they provide plenty of alpine scenery and mountain hiking. Anywhere that you go in Yellowstone, you have only to look into the horizon and note the rise of the mountains to see the remnants of the caldera rim.

Yellowstone Lake fills the eastern part of the caldera and offers opportunities for boating and fishing expeditions in the summer.

A sampling of hikes that allow you to see more of the caldera remnants follows:

• Lake Overlook
  The trail begins at a trailhead maker near the entrance of the West Thumb Geyser Basin parking area and climbs through a mountain meadow to a commanding view of the West Thumb of Yellowstone Lake and the surrounding Absaroka Mountains.
  Moderate difficulty. 2 miles roundtrip.
• Elephant Back Mountain
  The trail begins at a turnout 1 mile south of the Fishing Bridge Junction and then climbs through a lodge pole pine forest. At the junction of two trails, you can take either trail to a panoramic view of Yellowstone Lake, Pelican Valley and the Absaroka Mountains.
  Moderate to difficult. 3 miles roundtrip.
• Pelican Creek
  Take the trail starting at the west end of Pelican Creek bridge, 1.0 mile east of the Fishing Bridge Visitor Center, and travel this diverse, easy trail through forest, along lake shore, and across a marshy area via boardwalks.
  Easy. 1 mile roundtrip.
• Storm Point
  Starting at a large turnout at Indian Pond, 3 miles east of the Fishing Bridge Visitor Center, this level loop crosses meadow and forest before reaching the tip of Storm Point, where you will find expansive views of Yellowstone Lake and surrounding mountains. The trail will continue back along the lakeshore and through a lodge pole pine forest before rejoining the road.
  Easy to moderate. 3 miles roundtrip

 Learn More 

• Visit any of the Park’s Visitor Centers, explore the exhibits, and view the various information videos.
• Participate in a ranger-led activity to learn more about the formation of and the current day remnants of Yellowstone National Park caldera.
• Check out the local museums, both in the Park and in the surrounding communities.