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 ...

When you consider plate tectonics we often think of hot magma bubbling up from the Earth’s mantle, and we remember the vast assortment of pictures that we’ve seen–images featuring hundreds of active ...

POTASSIUM–ARGON age determinations have been carried out mainly on minerals with a high potassium content, particularly micas and potassium feldspars, found in intermediate to acid igneous rocks, but ...

Introduction -- Physical properties of magma -- Intrusion of magma -- Forms of igneous bodies -- Cooling of igneous bodies and other diffusion processes -- Classification of igneous rocks -- ...

Sedimentary rocks are made up of pieces of older rocks (igneous, metamorphic, and sedimentary) and organic remains (shells, bone, etc.). When rocks break apart from erosion they are transported by ...

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 ...

With house-size boulders tumbled across its scarred surface and slanted, twisted peaks looming over its iconic namesake trees, Joshua Tree National Park’s preternatural terrain evokes extraterrestrial ...

When driving from Malvern to Hot Springs on U.S. 270, I often take a short detour through one of the most interesting and unusual places in the state: Magnet Cove. Geologist Michael J. Howard has ...

Scientists on NASA's Perseverance mission made a surprising discovery about the composition of rock in Jezero Crater, one that will help them get a better idea of when water existed on Mars, and ...

Pockets of microbes have been found living within a sealed fracture in 2-billion-year-old rock. The rock was excavated from the Bushveld Igneous Complex in South Africa, an area known for its rich ore ...