The Island Park Caldera, in the U.S. states of

Idaho Idaho ( ) is a state in the Pacific Northwest region of the Western United States. To the north, it shares a small portion of the Canada–United States border with the province of British Columbia. It borders the states of Montana and Wyomi ...

and

Wyoming Wyoming () is a state in the Mountain West subregion of the Western United States. It is bordered by Montana to the north and northwest, South Dakota and Nebraska to the east, Idaho to the west, Utah to the southwest, and Colorado to the s ...

, is one of the world's largest

caldera A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcano eruption. When large volumes of magma are erupted over a short time, structural support for the rock above the magma chamber is ...

s, with approximate dimensions of 80 by 65 km. Its

ashfall The Ashfall Fossil Beds of Antelope County, Nebraska, Antelope County in northeastern Nebraska are rare fossil sites of the type called lagerstätten that, due to extraordinary local conditions, capture an ecological "snapshot" in time of a rang ...

is the source of the

Huckleberry Ridge Tuff The Huckleberry Ridge Tuff is a tuff formation created by the Huckleberry Ridge eruption that formed the Island Park Caldera that lies partially in Yellowstone National Park, Wyoming and stretches westward into Idaho into a region known as Island ...

that is found from

southern California Southern California (commonly shortened to SoCal) is a geographic and cultural region that generally comprises the southern portion of the U.S. state of California. It includes the Los Angeles metropolitan area, the second most populous urban a ...

to the

Mississippi River The Mississippi River is the second-longest river and chief river of the second-largest drainage system in North America, second only to the Hudson Bay drainage system. From its traditional source of Lake Itasca in northern Minnesota, it fl ...

near

St. Louis St. Louis () is the second-largest city in Missouri, United States. It sits near the confluence of the Mississippi and the Missouri Rivers. In 2020, the city proper had a population of 301,578, while the bi-state metropolitan area, which e ...

. This super-eruption of approximately occurred 2.1 Ma (million years ago) and produced 2,500 times as much ash as the

1980 eruption of Mount St. Helens On March 27, 1980, a series of volcanic explosions and pyroclastic flows began at Mount St. Helens in Skamania County, Washington, United States. A series of phreatic blasts occurred from the summit and escalated until a major explosive er ...

. Island Park Caldera has the smaller and younger

Henry's Fork Caldera The Henry's Fork Caldera in eastern Idaho is a caldera located in an area known as Island Park, west of Yellowstone National Park. The caldera was formed by an eruption 1.3 million years ago of the Yellowstone hotspot. The eruption distributed ...

nested inside it. The caldera clearly visible today is the later Henry's Fork Caldera, which is the source of the Mesa Falls Tuff. It was formed 1.3 Ma in an

eruption Several types of volcanic eruptions—during which lava, tephra (ash, lapilli, volcanic bombs and volcanic blocks), and assorted gases are expelled from a volcanic vent or fissure—have been distinguished by volcanologists. These are often ...

of more than . The two nested calderas share the same rim on their western sides, but the older Island Park Caldera is much larger and more oval and extends well into

Yellowstone National Park Yellowstone National Park is an American national park located in the western United States, largely in the northwest corner of Wyoming and extending into Montana and Idaho. It was established by the 42nd U.S. Congress with the Yellowst ...

.Newhall and Daniel Dzurisin, 1988, "Historical Unrest at Large Calderas of the World", ''U.S. Geological Survey Bulletin'' 1855. The Island Park Caldera is sometimes referred to as the First Phase Yellowstone Caldera or the Huckleberry Ridge Caldera. To the southwest of the caldera lies the Snake River Plain, which was formed by a succession of older calderas marking the path of the

Yellowstone hotspot The Yellowstone hotspot is a volcanic hotspot in the United States responsible for large scale volcanism in Idaho, Montana, Nevada, Oregon, and Wyoming, formed as the North American tectonic plate moved over it. It formed the eastern Snake Riv ...

. The plain is a depression, sinking under the weight of the volcanic rocks that formed it, through which the Snake River winds. Other observable volcanic features in the plain include: the

Menan Buttes The North and South Menan Buttes in southeastern Idaho are two of the world's largest volcanic tuff cones. The two cones, with four smaller associated cones, align along a north-northwest line and comprise the Menan Complex. The buttes rise abou ...

, the Big Southern Butte, Craters of the Moon, the Wapi Lava Field and Hell's Half Acre. These calderas are in an area called Island Park that is known for beautiful forests, large springs, clear streams, waterfalls, lakes, ponds, marshes, wildlife, and fishing. Harriman State Park is located in the caldera. Snowmobiling, fishing, and Nordic skiing, and wildlife viewing are popular activities in the area. The peaks of the

Teton Range The Teton Range is a mountain range of the Rocky Mountains in North America. It extends for approximately in a north–south direction through the U.S. state of Wyoming, east of the Idaho state line. It is south of Yellowstone National Park and ...

to the southeast are visible from places in the caldera.

References

External links

Yellowstone and Island Park calderas
{{Coord, 44.33, N, 111.33, W, source:frwiki_region:US_scale:100000, display=title Calderas of Idaho Calderas of Wyoming Yellowstone hotspot Volcanism of Idaho Volcanism of Wyoming Volcanoes of Idaho Landforms of Fremont County, Idaho Hotspot volcanoes Pleistocene calderas Neogene Idaho Neogene geology of Wyoming VEI-8 volcanoes Supervolcanoes Events that forced the climate

See also

References

External links