Maar

Maar

A maar is a broad, low-relief volcanic crater that is caused by a phreatomagmatic eruption, an explosion caused by groundwater coming into contact with hot lava or magma. The maar typically fills with water to form a relatively shallow crater lake. The name comes from a local Palatinate German dialect of Daun, which is in turn derived from Latin "mare" (sea). Maars are shallow, flat-floored craters that scientists interpret as having formed above diatremes as a result of a violent expansion of magmatic gas or steam; deep erosion of a maar presumably would expose a diatreme. Maars range in size from 60 meters (200 ft) to 2000m (6,500ft) across and from 10 meters (30ft) to 200 meters (650ft) deep, and most are commonly filled 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.

Maars occur in western North America, in the Eifel region of Germany (where they were originally described), and in other geologically young volcanic regions of Earth. Kilbourne Hole and Hunt's Hole, near El Paso, Texas, are maars. The notorious, carbon dioxide-saturated Lake Nyos in Africa is another example. An excellent example of a maar is Zuni Salt Lake in New Mexico, a shallow saline lake that occupies a flat-floored crater about convert|6500|ft|m|-1 across and convert|400|ft|m|-1 deep. Its low rim is composed of loose pieces of basaltic lava and wallrocks (sandstone, shale, limestone) of the underlying diatreme, as well as random chunks of ancient crystalline rocks blasted upward from great depths. The only maar-like volcano known in Canada is found in the Wells Gray-Clearwater volcanic field in east-central British Columbia. [ [http://gsc.nrcan.gc.ca/volcanoes/type_e.php Volcanoes of Canada] - Types of volcanoes. Retrieved on 2007-10-14]

One of the most famous misidentified maars is Meteor Crater in Arizona that for many years was thought to be of a volcanic rather than meteorite origin.. [ [http://www.barringercrater.com/science/ The Science: What is the Barringer Meteorite Crater?] ]

References

* [http://volcanoes.usgs.gov/Products/Pglossary/maar.html USGS Photo glossary of volcano terms: Maar]
* [http://vulcan.wr.usgs.gov/Glossary/Maars/description_maars.html USGS: Maars and Tuff Cones]

External links

* [http://volcanodb.com/volcanoes/Maar/ List of Maar Volcanoes]
* [http://volcano.und.edu/vwdocs/volc_images/north_america/morale_claim.html Morale Claim Maar, Arizona]


Wikimedia Foundation. 2010.

Игры ⚽ Нужно сделать НИР?

Look at other dictionaries:

  • maar — maár s. n. Trimis de siveco, 10.08.2004. Sursa: Dicţionar ortografic  MAÁR s.n. (geol.) Depresiune rotundă, asemănătoare unui crater de dimensiuni relativ mici, mărginită de un val alcătuit din tufuri vulcanice sau din material care nu este de… …   Dicționar Român

  • Maar — 〈n. 11; Geol.〉 mit Wasser gefüllte, runde Bodenvertiefung vulkanischen Ursprungs [<vulgärlat. mara „stehendes Gewässer, See“ <lat. mare „Meer“] * * * I Maar   [wohl aus vulgärlateinisch mara »stehendes Gewässer«, »See«, von lateinisch mare… …   Universal-Lexikon

  • Maar — Sn Kratersee per. Wortschatz fach. (20. Jh.) Entlehnung. Entlehnt aus spl. mara f. See , das auf l. mare Meer (Meer) zurückgeht. Als Bestandteil von Namen schon früher bezeugt.    Ebenso nndl. maar, kratermeer, ne. maar, nfrz. maar, nisl. mar (… …   Etymologisches Wörterbuch der deutschen sprache

  • maar — ● maar nom masculin (allemand Maar, cratère) Cratère d explosion volcanique, généralement occupé par un lac …   Encyclopédie Universelle

  • maar — maȃr m DEFINICIJA geol. vulkanska udubina u tlu, većinom ispunjena vodom ETIMOLOGIJA njem. Maar ← nizoz …   Hrvatski jezični portal

  • Maar [1] — Maar, See, welcher in einem verloschenen Krater eines Vulkans entstanden ist …   Pierer's Universal-Lexikon

  • Maar [2] — Maar (Ülmener), kleiner Landsee im Regierungsbezirk Coblenz der preußischen Rheinprovinz …   Pierer's Universal-Lexikon

  • Maar — Maar, kesselförmige, oft mit Wasser gefüllte und von einem Schlackenkranze umgebene Einsenkung in vulkanischen Gegenden, meist kreisrund, z.B. in der Eifel …   Kleines Konversations-Lexikon

  • Maar — 〈n.; Gen.: (e)s, Pl.: e; Geogr.〉 mit Wasser gefüllte runde Bodenvertiefung vulkanischen Ursprungs [Etym.: <vulgärlat. mara »stehendes Gewässer, See« <lat. mare »Meer«] …   Lexikalische Deutsches Wörterbuch

  • Maar — (izg. mȃr), Dora (pravo ime Henriette Théodora Markovich) (1907 1997) DEFINICIJA francuska slikarica i fotografkinja hrv. porijekla; živjela s Picassom u Parizu 1936 1943, fotografski dokumentirala njegov rad na Guernici; Picasso ju je često… …   Hrvatski jezični portal

  • Maar — Maar, das; [e]s, e (Geografie kraterförmige Senke) …   Die deutsche Rechtschreibung

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”