Tap this image to learn more about the textbook that supports this learning resource.

Using Igneous Rocks to Interpret Earth History

Click on the link above to start the learning activity

"Every rock has a story to tell. The story of an igneous rock begins when rock in the lower crust or upper mantle melts to form molten material called magma, which rises up through the crust. Some magma fl ows or spatters out on the surface as lava, or it explodes into the air as tiny particles of volcanic ash or larger blocks. Igneous rock that forms from solidify ed lava or ash is called extrusive igneous rock because it comes out (extrudes) onto the surface. Other magma never reaches the surface and solidifi es underground to form intrusive igneous rock, so called because it squeezes into (intrudes) the surrounding rocks."

From: Laboratory Manual for Introductory Geology
by Ludman and Marshak