One way to find water worlds beyond our solar system could be to look for minerals — or more specifically, to study minerals mixed with cool lava on exoplanet surfaces. This is because if water ...

Left: A close-up of a crack in the volcanic surface of a cooled lava flow from the crater of Mt. St. Helens.

As it pours down the volcano, the lava at the surface is cooled by the air and solidifies, creating an elastic, skinlike outer layer. Beneath this inflating membrane, the lava continues to ooze ...

Hallmundarhraun, just a few hours’ drive from Reykjavík, is riven with lava tubes which form when fresh molten rock flows through an existing field of cooled lava. Over time, the ceilings of ...

Another potential hazard is Pele's hair, a volcanic glass formation produced from cooled lava that's stretched into thin ...

a fresh deposit of liquid lava will trickle through the porous cooled lava, forming as it solidifies the pendant stalactites shown in the accompanying picture, which illustrates Mr. Goldsmith's ...