Pumice is an example of extrusive igneous rock. The word extrusive means that the magma was forced onto the earth's surface and cooled in a matter of hours. Granite is an example of intrusive igneous ...

In my last column, I wrote about the locations where you can find igneous rocks that were formed from lava. The metarhyolite and metabasalt described in the column are known as extrusive rocks, those ...

Kris Wang is a fourth-year undergraduate student at Scripps Institution of Oceanography at UC San Diego, where he is studying geosciences with a focus on volcanology and igneous petrology.