Subglacial mound

Palagonitrücken and Palagonitkegel are a type of subglacial volcanoes caused by explosive eruptions beneath a glacier. The Locker thereby ejected masses ( tephra ) solidify immediately to volcanic glass, are converted by the abundance of water with time in palagonite and caked to tuff.

If there is a fissure eruption, produced an elongated Palagonitrücken when only a single central vent erupts, there is formation of a Palagonitkegels.

If the Vulkanbauten from the glacier, and water grow out, the lava can also effusive flow out and form lava flows, which are no longer converted to palagonite. The resulting volcano form is called plaque volcano or Tuya.

Most Palagonitrücken formed during the last ice age, or before last and are now mostly free of ice.

Occurrence

Palagonitrücken get there before, where there has been in the past, large ice cover over volcanic regions, ie, in Canada, in the Antarctic, but especially in Iceland, where they are very common and are also known as Moberg ridge.

Examples of Palagonitrücken in Iceland are the Einhyrningur and Helgafell í Mosfellssveit. A particularly uniform Palagonitkegel is the Keilir.