I am learning about this in my Science class, and when a geologist looks at an extrusion, they know it's an extrusion because it is Igneous rock, and an extrusion helps tell the reletive ages of the layers around it.

The Lepore Extrusion was created on 2006-10-17.

The Mary-Sue Extrusion was created in 1999.

Kurt Laue has written:

'Strangpressen' -- subject(s): Extrusion, Metals

'Extrusion' -- subject(s): Extrusion, Metals

That is the correct spelling of "extrusion" (forming by pressing through a die or opening).