Fumarole Butte volcanic complex 1978 AR1VERD00020029

Fumarole Butte is a

shield volcano A shield volcano is a type of volcano named for its low profile, resembling a warrior's shield lying on the ground. It is formed by the eruption of highly fluid (low viscosity) lava, which travels farther and forms thinner flows than the more v ...

in central

Juab County Juab County ( ) is a county in western Utah, United States. As of the 2010 United States Census, the population was 10,246. Its county seat and largest city is Nephi. Juab County is part of the Provo–Orem, Utah Metropolitan Statistica ...

Utah Utah ( , ) is a state in the Mountain West subregion of the Western United States. Utah is a landlocked U.S. state bordered to its east by Colorado, to its northeast by Wyoming, to its north by Idaho, to its south by Arizona, and to its ...

, United States. Built during the Quaternary period, it is composed of

basaltic andesite Basaltic andesite is a volcanic rock that is intermediate in composition between basalt and andesite. It is composed predominantly of augite and plagioclase. Basaltic andesite can be found in volcanoes around the world, including in Central Ameri ...

. It stands in height and has a diameter of . Under the volcano lies Crater Bench, the result of an eruption of basaltic andesite. To the east of the volcano are a series of

hot springs A hot spring, hydrothermal spring, or geothermal spring is a spring produced by the emergence of geothermally heated groundwater onto the surface of the Earth. The groundwater is heated either by shallow bodies of magma (molten rock) or by c ...

, known as

Baker Hot Springs Baker Hot Springs are a system of geothermal springs located on Fumarole Butte, northwest of the town of Delta, Utah. The springs were formerly known as Crater Springs and Abraham Hot Springs. Water profile The hot mineral water emerges from ...

Background

Fumarole Butte is located in the area once dominated by

Lake Bonneville Lake Bonneville was the largest Late Pleistocene paleolake in the Great Basin of western North America. It was a pluvial lake that formed in response to an increase in precipitation and a decrease in evaporation as a result of cooler temperature ...

, a massive body of water nearly in area. The lake was created more than 800,000 years ago by extensive precipitation and glacier melting, and has dried up and re-emerged at least 28 times since. The cycles have been matched almost exactly to periods of glaciation by drilling and stratigraphic studies.

Description

Fumarole Butte lies north of the

Sevier Desert The Sevier Desert is a large arid section of central-west Utah, United States, and is located in the southeast of the Great Basin. It is bordered by deserts north, west, and south; its east border is along the mountain range and valley sequences ...

. It is located in the

scoria Scoria is a pyroclastic, highly vesicular, dark-colored volcanic rock that was ejected from a volcano as a molten blob and cooled in the air to form discrete grains or clasts.Neuendorf, K.K.E., J.P. Mehl, Jr., and J.A. Jackson, eds. (2005) ' ...

-rich valley of a basaltic

lava field Lava fields are large, mostly flat areas of surface or subaquatic lava flows. Such features are generally composed of highly fluid basalt lava, and can extend for tens or hundreds of miles across the underlying terrain. Morphology and str ...

, on top of

Tertiary Tertiary ( ) is a widely used but obsolete term for the geologic period from 66 million to 2.6 million years ago. The period began with the demise of the non- avian dinosaurs in the Cretaceous–Paleogene extinction event, at the start ...

-aged structures of rhyolitic lava. Made of red and gray material, its composition ranges from dark basalt to reddish scoria. Fumarole Butte formed during the

Jaramillo normal event The Jaramillo normal event is a period of normal polarity of Earth's magnetic field during the Matumaya Reversed Epoch. The Jaramillo normal event is dated to 1.06 to 0.9 million years ago in the stratigraphic record of Pleistocene epoch rocks ...

, approximately one million years ago. It is a

with a

volcanic neck A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plates ar ...

protruding from the center. On the edges of the volcano,

lacustrine A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much larger ...

deposits can be found where the volcano was once covered by

Crater Bench Formation

Eruptions from Fumarole Butte created the basaltic Crater Bench Formation, which lies beneath the neck. It is around 900,000 years of age, dated to the

Pleistocene The Pleistocene ( , often referred to as the '' Ice age'') is the geological epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was finally confirmed ...

. The area is divided by faults and ranges in thickness from to . The primary component of the lava is aphyric

in which tiny crystalline structures are visible.

References

External links

* {{coord, 39.61, -112.79, display=title Shield volcanoes of the United States Volcanoes of Utah Landforms of Juab County, Utah Buttes of Utah