Maar

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).

[3] The name maar comes from a Moselle Franconian dialect word used for the circular lakes of the Daun area of Germany.

[Note 1] The present definition of the term[1] relates to both its common and scientific discourse use in language over two centuries.

Depending upon context there may be other descriptors available to use in the geological sciences such as the term tuff ring or maar-diatreme volcanoes.

After winters of heavy snow and rainfall many dry maars fill partially and temporarily with water; others contain small bogs or often artificial ponds that, however, only occupy part of the hollow.

[citation needed] The largest known maars are found at Espenberg on the Seward Peninsula in northwest Alaska.

Their large size is due to the explosive reaction that occurs when magma comes into contact with permafrost.

Elsewhere in Europe, La Vestide du Pal, a maar in the Ardèche department of France, is easily visible from the ground or air.

The Crocodile Lake in Los Baños in the Philippines, though originally thought to be a volcanic crater, is a maar.

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.

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.

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.

[citation needed] The San Pablo Volcanic Field in the Province of Laguna on the island of Luzon in the Philippines contains maars.