Víðgelmir

Víðgelmir is one of the longest (1.585 m) caves in Iceland and largest (148.000 m³) lava tube cave in the world. [cite web
title =Hellirinn Víðgelmir
work =Caves of Iceland
publisher =Showcaves
date =September 2007
url =http://www.showcaves.com/english/misc/showcaves/Vidgelmir.html
accessdate =2007-09-11 ] It's situated in Western Iceland in the Hallmundarhraun lava field, ca. 2 km. Southeast from Fljótstunga [cite web
title =Víðgelmir Cave
url =http://fljotstunga.is/ensk_hellir.htm
accessdate =2007-09-11 ] farm in Hvítársíða, Borgarfjörður. The roof of the lava tube has collapsed, creating two large openings near its north end which are the only known entrances. The cave entrance is wide but narrows down in some places. An iron gate was installed at the first constriction in 1994 to preserve the delicate lava formations or speleothems which haven't already been destroyed. Evidence of human habitation, probably dating to the Viking age, has been discovered in the cave and is preserved in the National Museum of Iceland. Long stretches of the cave floor are very rough and shouldn't be navigated without a guide. Access and guided tours are provided at nearby Fljótstunga.

Lava tube caves are formed when a low-viscosity lava flow develops a continuous and hard crust which thickens and forms a roof above the molten lava stream. When the eruption subsides, the still molten lava moving beneath the crust will continue to drain downhill, leaving an open lava tube cave. Many other lava tube caves have been discovered in Hallmundarhraun, most notable Surtshellir and Stefánshellir.

Notes

External links

* [http://www.goodearthgraphics.com/virtual_tube/virtube.html The Virtual Lava Tube] Large educational site on lava tube features and how they form.
* [http://www.fljotstunga.is Fljótstunga website]
* [http://www.flickr.com/gp/49198643@N00/jK002m Vidgelmir images] From July 2007.