Extrusive

Extrusion (Latin extrudere = cast out, push out ) describes the geology of the rising viscous magma in volcanoes. Originally the term in 1897 by Sir Archibald Geikie was created for the outflow of lava and ejection of loose masses of volcanoes.

Today the term is used in Germany almost exclusively for the processes involved in the formation of volcanic domes and Lavanadeln. Examples of such incurred by extrusion source and domes can be found about the Seven Mountains, in the Rhön, in Auvergne, on Santorini and in many other volcanic regions of the earth.

Extrusion as the outflow of salt is further referred to the surface. Examples of this process are found in the salt glaciers in the Zagros Mountains of Iran.

Outside the German-speaking world, the original meaning of the term has held.