Maar - WikiHQ

thumb|The ten-day [[phreatomagmatic eruption that formed the Ukinrek maars]]

thumb|The [[Devil Mountain Lakes on the Seward Peninsula in western Alaska – the largest maar-based lakes in the world]]

A maar is a broad, low-relief volcanic crater caused by a phreatomagmatic eruption (an explosion which occurs when groundwater comes into contact with hot lava or magma). A maar characteristically fills with water to form a relatively shallow crater lake, which may also be called a maar.

Maars generally range in size from across and from deep. Most maars fill with water to form natural lakes. Most maars have low rims composed of a mixture of loose fragments of volcanic rocks and rocks torn from the walls of the diatreme. The present definition of the term These last are volcanoes produced by explosive eruptions that cut deeply into the country rock with the maar being "the crater cut into the ground and surrounded by an ejecta ring".

Maars occur in western North America, Patagonia in South America, the Eifel region of Germany (where they were originally described), and in other geologically young volcanic regions of Earth. Elsewhere in Europe, La Vestide du Pal, a maar in the Ardèche department of France, is easily visible from the ground or air. Kilbourne Hole and Hunt's Hole, in southern New Mexico near El Paso, Texas, are maars. The Crocodile Lake in Los Baños in the Philippines, though originally thought to be a volcanic crater, is a maar. The carbon dioxide-saturated Lake Nyos in northwestern Cameroon is another example, as is Zuñi Salt Lake in New Mexico, a shallow saline lake that occupies a flat-floored crater about across and deep. Its low rim is composed of loose pieces of basaltic lava and wall rocks (sandstone, shale, limestone) of the underlying diatreme, as well as chunks of ancient crystalline rocks blasted upward from great depths. Maars in Canada are found in the Wells Gray-Clearwater volcanic field of east-central British Columbia and in kimberlite fields throughout Canada. Another field of maars is found in the Pali-Aike Volcanic Field in Patagonia, South America. and in the Sudanese Bayuda Volcanic Field. The Auckland volcanic field in the urban area of Auckland, New Zealand, has several maars, including the readily accessible Lake Pupuke in the North Shore suburb of Takapuna.

Arizona's Meteor Crater was for many years thought to be a maar of volcanic origin but it is now known to be an impact crater.

Germany

Eifel maars

thumb|The three maars at Daun (from front to rear): the Gemündener, Weinfelder and Schalkenmehrener Maar

thumb|Weinfelder Maar

thumb|Schalkenmehrener Maar

In the Volcanic Eifel there are about 75 maars. Both lake-filled and dry maars are typical, though the latter are more common. The last eruptions took place at least 11,000 years ago, and many maars are older, as evidenced by their heavy erosion and less obvious shapes and volcanic features.

Water-filled maars of the Eifel

{| class="wikitable sortable toptextcells"

|- style="vertical-align:top; "

! Name Geo-coordinates

! Location near/between

! Area in ha

! Depth The location of one such maar was Elie Ness.

Americas

thumb | [[Kilbourne Hole in the Potrillo volcanic field of New Mexico]]

Active maar volcanoes are mainly known outside Europe.

In the US there are numerous maar areas, such as in Alaska (Ukinrek maars, Nunivak in the Bering Sea); in Washington (Battle Ground Lake); in Oregon (Fort Rock basin with the maars of Big Hole, Hole-in-the-Ground, Table Rock); in Death Valley National Park, California (Ubehebe Crater); in Nevada (Soda Lakes); as well as the maars of the White Rock Canyon, Mount Taylor, the Potrillo volcanic fields (Kilbourne Hole and Hunt's Hole), and Zuñi Salt Lake in New Mexico.

In Central Mexico, the Tarascan volcanic field contains several maars in the states of Michoacán and Guanajuato. The Río Cuarto and Hule maars are in Costa Rica. In Nicaragua is the maar of Laguna de Xiloa, part of the Apoyeque volcano. From South America, there are known maars in Chile (e.g. Cerro Overo and Cerro Tujle in northern Chile). Jayu Khota is a maar in Bolivia.

Middle East and Africa

The maar of Lake Ram

Asia and Oceania

thumb|[[Blue Lake / Warwar, a maar at Mount Gambier, South Australia]]

In Japan there are maars in the Kirishima-Yaku volcanic field in the Kirishima-Yaku National Park on Kyushu. These include the several maars of the Ibusuki volcanic field such as Lake Unagi. On Honshu in Myōkō-Togakushi Renzan National Park there is Kagamiike Pond as well as many on the volcanic island of Miyake-jima, Izu Islands (Furumio, Mi'ike, Mizutamari, Shinmio).

Koranga Maar and Numundo Maar are in Papua New Guinea. Kawah Masemo maar is on Mount Sempu volcano in Indonesia. The San Pablo Volcanic Field in the Province of Laguna on the island of Luzon in the Philippines contains maars.

The Newer Volcanics Province in the States of South Australia and Victoria, Australia, has numerous maars, such as Mount Gambier, Mount Schank and Tower Hill, whose complex system of nested maars is enclosed by one of the largest maars in the world.

Foulden Maar in Otago, New Zealand, is an important fossil site, but there are many more maars in New Zealand. As already mentioned these include Lake Pupuke, but the Auckland volcanic field has other easily accessible maars such as the Mangere Lagoon, Orakei Basin, Panmure Basin, and Pukaki Lagoon. Elsewhere a recent example, only 4000 years old, is Lake Rotokawau in the Bay of Plenty Region.

Gallery

Image:Totenmaar weinfelder maar eifel.jpg|Weinfelder Maar, one of the three maars originally described

Image:Maar Israel.JPG|The maar at Birkat Ram, the Golan Heights

Image:Zengena Hayq.JPG|Zengena Lake, a maar in Amhara Region, Ethiopia

Image:Pinacate_volcanic_field.jpg|El Elegante Crater, in Sonoran Desert, Mexico

Image:BVFMuweilihCrater.jpg|El Muweilih Crater, a maar in Bayuda volcanic field, Sudan: Natron-rich clay on the crater floor

File:Hunt's Hole aerial 1.jpg|Hunt's Hole in the Potrillo volcanic field of New Mexico

File:Kluft-photo-SodaLake-rim-2018-11.jpg|Big Soda Lake in Nevada

File:Lake Rotokawau.jpg|Lake Rotokawau in New Zealand

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Footnotes

References

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Literature

USGS photo glossary: Maar
USGS: Maars and tuff cones

External links

Formation of volcanoes - maar, animation on YouTube, Czech Geological Survey, 2019, duration 1 min 56 sec. English subtitles available. Retrieved 2025-02-04.
List of Maar Volcanoes
La Vestide du Pal