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 ...

This hidden geological layer, located between 254 and 410 miles (410 and 660 kilometers) beneath the Earth’s surface, covers an extraordinary distance of 205 miles (330 kilometers), hinting at a ...

Extrusive igneous rocks are formed by magma that has erupted onto the surface as lava and then cooled quickly. Obsidian is an example of an extrusive igneous rock.

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 ...

Basalt is what’s known as an extrusive igneous rock - it is volcanic, formed from molten magma that extruded onto the Earth’s surface and hardened. It is dark in color and heavy and dense.

Basalt is what’s known as an extrusive igneous rock - it is volcanic, formed from molten magma that extruded onto the Earth’s surface and hardened. It is dark in color and heavy and dense.

An extrusive igneous rock is formed from molten magma coming from the interior of the earth on its surface, rapidly cools down and becomes solid.

A recent study changes the understanding of how the Hawaiian Islands formed. Scientists have determined that it is the eruptions of lava on the surface, extrusion, which grow Hawaiian volcanoes ...

It is an extrusive igneous rock comprised of feldspar and quartz, endemic to volcanic regions. Several dozen localities have been studied by geologists, each distinct with its own chemical ...

Previous estimates of the internal-to-extrusive ratios (internally emplaced magma versus extrusive lava flow) were based on observations over a very short time frame, in the geologic sense.