(CNN) — Here's some background information about volcanoes, mountains that open downward to a reservoir of molten rock. Facts: More than 80% of the Earth's surface, both above and below sea level, is ...

Volcanoes are Earth’s geologic architects. They’ve created more than 80 percent of our planet’s surface, laying the foundation that has allowed life to thrive. Their explosive force crafts mountains ...

Add Yahoo as a preferred source to see more of our stories on Google. Smoke billows from the mouth of Mt. Shasta like a thunderous cough. Within moments, clear skies turn gray, and the sun vanishes ...