Mountain Keilir surrounded by lava fields
Taken in moss covered lavafields in south-west Iceland with mountain Keilir in the background. Keilir is a pyramid-shaped mountain that was formed during an eruption under a glacier in one of the ice ages, without reaching the surface of the glacier. The mountain consists of tuff, being a type of rock consisting of consolidated volcanic ashes. When a volcano erupts many materials including ash, fragments of rock, and other miscellaneous materials are emitted. This matter falls to the earth and cools forming a variety of rocks that include tuff.