The flows of Jordan Craters volcanic field are the youngest of a series of large

Quaternary The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS), as well as the current and most recent of the twelve periods of the ...

basalt Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial ...

fields in the eastern part of the

U.S. state In the United States, a state is a constituent political entity, of which there are 50. Bound together in a political union, each state holds governmental jurisdiction over a separate and defined geographic territory where it shares its so ...

Oregon Oregon ( , ) is a U.S. state, state in the Pacific Northwest region of the United States. It is a part of the Western U.S., with the Columbia River delineating much of Oregon's northern boundary with Washington (state), Washington, while t ...

. The field is thought to be approximately 3200 years old, based on findings of a lake sediment coring experiment in 1986. It was formed by basaltic

pahoehoe Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a moon onto its surface. Lava may be erupted at a volcano or through a fracture in the crust, on land or unde ...

emanating from vents throughout the area. The most recent flows come from Coffeepot Crater, a large breached

cinder cone A cinder cone or scoria cone is a steep, volcanic cone, conical landform of loose pyroclastic rock, pyroclastic fragments, such as volcanic ash, clinkers, or scoria that has been built around a volcanic vent. The pyroclastic fragments are forme ...

. These flows show excellent examples of inflated lava. Historically, it is believed that Coffeepot Crater held a pond of lava that would occasionally breach the sides of the crater to flow freely into the field. Jordan Craters is approximately 120 miles (200 km) southwest of

Boise, Idaho Boise ( ) is the List of capitals in the United States, capital and List of cities in Idaho, most populous city of the U.S. state of Idaho. As of the 2020 United States census, 2020 census, there were 235,685 people residing in the city. Loca ...

and 18 miles (30 km) northwest of

Jordan Valley, Oregon Jordan Valley is a city in Malheur County, Oregon, United States. It is part of the Ontario, OR– ID Micropolitan Statistical Area. The city lies along Jordan Creek, a tributary of the Owyhee River; the creek is named for a 19th-century ...

. The craters are free and open to the public all year.

References

(archived) Volcanic fields of Oregon Landforms of Malheur County, Oregon Volcanoes of Oregon {{MalheurCountyOR-geo-stub

See also

References