Yellowstone National Park's geological history is one of the most intensely studied in North America. A new geologic unit ...

Lava is the form of magma that erupts to the surface, such as via a volcano. Here is how hot it is.

In geology, even small layers can tell big stories. But figuring out the origins of such small layers can be a challenge, ...

New age data for rhyolite lava flows erupted in the Yellowstone caldera suggest the eruptions occurred in tight clusters, changing the way geologists think about lava flow events and volcanic ...

Learn more about the new hydrothermal feature that appeared last summer in Yellowstone National Park, and how, even though it ...

Little Glass Mountain in the foreground, a rhyolite lava flow/dome, with small, tree-covered basaltic cinder cones at Medicine Lake in California. The volcano in the background is Shasta.

Because the rhyolite was very thick, dry and viscous, minerals in the lava couldn't form sizable crystals. Instead, the lava is solidified but disordered silica, like window glass.

In the heart of Oregon’s high desert, just south of Bend, lies a vast volcanic landscape that whispers tales of fire and transformation. This is Newberry Volcano—a colossal, yet often ...

Lava can be typed by chemical signature as well. Basaltic lava is mafic, an abbreviation of two of its prevalent elements, magnesium and ferrum, derived from the Latin word for iron. Rhyolitic lava is ...

A mafic volcanic eruption is one characterized by lava flows low in silica and high in iron and magnesium. Rhyolitic lava flows are viscous in nature and form lava domes that are thick and blocky.