Henry's Fork Caldera
Encyclopedia
Idaho
Idaho is a state in the Rocky Mountain area of the United States. The state's largest city and capital is Boise. Residents are called "Idahoans". Idaho was admitted to the Union on July 3, 1890, as the 43rd state....
is a caldera
Caldera
A caldera is a cauldron-like volcanic feature usually formed by the collapse of land following a volcanic eruption, such as the one at Yellowstone National Park in the US. They are sometimes confused with volcanic craters...
located an area known as Island Park
Island Park
Island Park may refer to:*Island Park, Idaho*Island Park, New York*Island Park *Island Park A baseball venue located in Harrisburg, PA from 1940 through 1942. It was the home base for the Harrisburg "Pirates" of the Inter-State League.*Island Park, Ottawa - neighbourhood in Ottawa named for Island...
west of Yellowstone National Park
Yellowstone National Park
Yellowstone National Park, established by the U.S. Congress and signed into law by President Ulysses S. Grant on March 1, 1872, is a national park located primarily in the U.S. state of Wyoming, although it also extends into Montana and Idaho...
. The caldera was formed by one of the world's supervolcano
Supervolcano
A supervolcano is a volcano capable of producing a volcanic eruption with an ejecta volume greater than 1,000 cubic kilometers . This is thousands of times larger than most historic volcanic eruptions. Supervolcanoes can occur when magma in the Earth rises into the crust from a hotspot but is...
s in an eruption of more than 280 cubic kilometers 1.3 million years BP
Before Present
Before Present years is a time scale used in archaeology, geology, and other scientific disciplines to specify when events in the past occurred. Because the "present" time changes, standard practice is to use AD 1950 as the origin of the age scale, reflecting the fact that radiocarbon...
, and is the source of the Mesa Falls Tuff
Mesa Falls Tuff
The Mesa Falls Tuff is a tuff formation created by the Mesa Falls eruption that formed the Henry's Fork Caldera that is located in Idaho west of Yellowstone Park. It is the second most recent caldera forming eruption from the Yellowstone hotspot and ejected of 280 km³ of material...
.
The Henry's Fork Caldera is nested inside of the Island Park Caldera
Island Park Caldera
The volcanic feature commonly called the Island Park Caldera in the states of Idaho and Wyoming, U.S., is actually two calderas, one nested inside the other. The Island Park Caldera is the older and much larger caldera, with approximate dimensions of 58 miles by 40 miles...
and the calderas share a rim on the western side. The earlier Island Park Caldera
Island Park Caldera
The volcanic feature commonly called the Island Park Caldera in the states of Idaho and Wyoming, U.S., is actually two calderas, one nested inside the other. The Island Park Caldera is the older and much larger caldera, with approximate dimensions of 58 miles by 40 miles...
is much larger and more oval and extends well into Yellowstone Park. Although much smaller than the Island Park Caldera
Island Park Caldera
The volcanic feature commonly called the Island Park Caldera in the states of Idaho and Wyoming, U.S., is actually two calderas, one nested inside the other. The Island Park Caldera is the older and much larger caldera, with approximate dimensions of 58 miles by 40 miles...
, the Henry's Fork Caldera is still sizeable at 18 miles (29 km) long and 23 miles (37 km) wide and its curved rim is plainly visible from many locations in the Island Park
Island Park
Island Park may refer to:*Island Park, Idaho*Island Park, New York*Island Park *Island Park A baseball venue located in Harrisburg, PA from 1940 through 1942. It was the home base for the Harrisburg "Pirates" of the Inter-State League.*Island Park, Ottawa - neighbourhood in Ottawa named for Island...
area. Of the many calderas formed by the Yellowstone hotspot
Yellowstone hotspot
The Yellowstone hotspot, also referred to as the Snake River Plain-Yellowstone hotspot, is a volcanic hotspot responsible for large scale volcanism in Oregon, Nevada, Idaho, and Wyoming, United States. It created the eastern Snake River Plain through a succession of caldera forming eruptions...
, including the later Yellowstone Caldera
Yellowstone Caldera
The Yellowstone Caldera is the volcanic caldera located in Yellowstone National Park in the United States, sometimes referred to as the Yellowstone Supervolcano. The caldera is located in the northwest corner of Wyoming, in which the vast majority of the park is contained. The major features of...
, the Henry's Fork Caldera is the only one that is currently clearly visible. It is one of a succession of supervolcanoes and calderas that formed the Snake River Plain
Snake River Plain
The Snake River Plain is a geologic feature located primarily within the state of Idaho in the United States of America. It stretches about westward from northwest of the state of Wyoming to the Idaho-Oregon border. The plain is a wide flat bow-shaped depression, and covers about a quarter of Idaho...
.
The Henrys Fork of the Snake River
Snake River
The Snake is a major river of the greater Pacific Northwest in the United States. At long, it is the largest tributary of the Columbia River, the largest North American river that empties into the Pacific Ocean...
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 Thurburn 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
Island Park, Idaho
Island Park is a city in Fremont County, Idaho, United States. The city's population was 215 at the 2000 census. The city was incorporated by owners of the many lodges and resorts along U.S. Route 20 in 1947, primarily to circumvent Idaho's liquor laws that prohibited the sale of liquor outside of...
that is known for beautiful forests, large springs, clear streams, waterfalls, lakes, ponds, marshes, wildlife, and fishing. Harriman State Park
Harriman State Park (Idaho)
Harriman State Park is a state park in eastern Idaho, USA. It is located on an wildlife refuge in the Greater Yellowstone Ecosystem and is home to an abundance of elk, moose, sandhill cranes, trumpeter swans, and the occasional black or grizzly bear. Two-thirds of the trumpeter swans that winter...
is situated in the caldera. The peaks of the Grand Tetons are visible to the southeast. Snowmobiling, fishing, and Nordic skiing, and wildlife viewing are popular activities in the area.