Extrusion (geology)

The Wolkenburg in the Siebengebirge , a dome created by extrusion

In geology, extrusion (Latin extrudere = to push out, to push out) describes the rising of viscous magma in volcanoes . The term was originally created in 1897 by Sir Archibald Geikie for the discharge of lava and the ejection of loose material from volcanoes.

Today in Germany the term is used almost exclusively for the processes involved in the formation of volcanic dunnage and lava needles . Examples of such source and damming dome formed by extrusion can be found in the Siebengebirge , in the Rhön , in the Auvergne , on Santorin and in many other volcanic regions of the world.

The flow of salt to the surface of the earth is also referred to as extrusion. Examples of this process can be found in the salt glaciers in the Zagros Mountains of Iran .

Outside of the German-speaking area, the original meaning of the technical term has remained.

See also

• Volcanic eruption
• Ejection
• Effusion (volcanism)
• Intrusion (geology)

literature

• Hans Murawski: Geological Dictionary. , 11th edition, Ferdinand Enke Verlag, Stuttgart 2004, 262 pages, ISBN 978-3-8274-1445-8