Pseudocrater

A pseudocrater is a volcanic landform which resembles a true volcanic crater, but differs in that it is not an actual vent from which lava has erupted. Pseudocraters are also known as "rootless cones", since they are characterised by the absence of any magma conduit which connects below the surface of the earth.

Pseudocraters are formed by steam explosions as flowing hot lava crosses over a wet surface, such as a swamp, a lake, or a pond. The explosive gases break through the lava surface in a manner similar to a phreatic eruption, and the tephra builds up crater-like forms which can appear very similar to real volcanic craters.

Well known examples are found in Iceland like the craters in the lake Mývatn ("Skútustaðagígar"), the "Rauðhólar" in the region of the capital city Reykjavík or the "Landbrotshólar" in the southeast of Iceland. Pseudocraters have also been discovered on Mars, which would suggest that there was once water on that planet.

ee also

* Volcanoes of Iceland

External links

* [http://www.lpi.usra.edu/meetings/sixthmars2003/pdf/3070.pdf Pseudocraters and Mars] (PDF file)