The Henry's Fork Caldera in eastern

Idaho Idaho ( ) is a landlocked U.S. state, state in the Pacific Northwest and Mountain states, Mountain West subregions of the Western United States. It borders Montana and Wyoming to the east, Nevada and Utah to the south, and Washington (state), ...

is a

caldera A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcanic eruption. An eruption that ejects large volumes of magma over a short period of time can cause significant detriment to the str ...

located in an area known as Island Park, west of

Yellowstone National Park Yellowstone National Park is a List of national parks of the United States, national park of the United States located in the northwest corner of Wyoming, with small portions extending into Montana and Idaho. It was established by the 42nd U ...

. The caldera was formed by an eruption 1.3 million years ago of the Yellowstone hotspot. The eruption distributed at least 280 cubic kilometers of ash known as the Mesa Falls Tuff, covering a region including all of Wyoming and most of Colorado, Nebraska, and Kansas. The Henry's Fork Caldera is nested inside of the Island Park Caldera, and the calderas share a rim on the western side. The earlier Island Park Caldera is much larger and more oval and extends well into Yellowstone Park. Although much smaller than the Island Park Caldera, the Henry's Fork Caldera is still sizeable at long and wide and its curved rim is plainly visible from many locations in the Island Park area. Of the many calderas formed by the Yellowstone hotspot, including the later Yellowstone Caldera, the Henry's Fork Caldera is the only one that is currently clearly visible.this qualitative statement is easily verified by reviewing the Yellowstone area in Google Earth It is one of a succession of volcanoes and calderas that formed the Snake River Plain. The Henrys Fork of the

Snake River The Snake River is a major river in the interior Pacific Northwest region of the United States. About long, it is the largest tributary of the Columbia River, which is the largest North American river that empties into the Pacific Ocean. Begin ...

flows through the Henry's Fork Caldera and drops out at Upper and Lower Mesa Falls. The caldera is bounded by the Ashton Hill on the south, Big Bend Ridge and Bishop Mountain on the west, by Thurmon Ridge on the North and by Black Mountain and the Madison Plateau on the east. The Henry's Fork caldera is in an area called Island Park, known for its beautiful forests, large springs, clear streams, waterfalls, lakes, ponds, marshes, wildlife, and fishing. Harriman State Park is situated within the caldera. 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, ...

in adjacent

Wyoming Wyoming ( ) is a landlocked U.S. state, state in the Mountain states, Mountain West subregion of the Western United States, Western United States. It borders Montana to the north and northwest, South Dakota and Nebraska to the east, Idaho t ...

are visible to the southeast. Snowmobiling, fishing, and Nordic skiing, and wildlife viewing are popular activities in the area.

References

{{coord, 44.33, N, 111.33, W, source:frwiki_region:US_scale:100000, display=title Yellowstone hotspot Volcanism of Idaho Calderas of Idaho Volcanoes of Idaho VEI-7 volcanoes Landforms of Fremont County, Idaho Pleistocene calderas Pleistocene United States Quaternary Idaho