Question

Where are extrusive rocks formed?

Answer 1

"Extrusive refers to the mode of igneous volcanic rock formation in which hot magma from inside the Earth flows out (extrudes) onto the surface as lava or explodes violently into the atmosphere to fall back as pyroclastics or tuff. This is as opposed to intrusive rock formation, in which magma does not reach the surface."


http://en.wikipedia.org/wiki/Extrusive