Oregon is home to some of the best examples ... formed by flowing lava moving underneath the hardened surface of a lava flow. Tubes act as a pressure relief valve of sorts, a natural drainage ...

The evidence is hiding in plain sight. What we see as Isle Royale and the Keweenaw Peninsula is actually part of the one of the largest known lava flows on Earth. A map of the different forms of ...

Mount Rainier in Washington is a famous stratovolcano. Shield volcanoes are big, broad volcanoes made up of oozy lava flows that erupt from multiple vents. Hawaii's Mauna Loa and Kilauea are both ...