The Little Glass Mountain obsidian flow is seen from Little Mount Hoffman on the western rim of Medicine Lake caldera with Mount Shasta in the background. The flow was erupted on the SW flank of Medicine Lake volcano a little more than 950 years ago. The light-colored rounded peak in line with Mount Shasta is Pumice Stone Mountain, which is overlain by pumice from the Little Glass Mountain eruption. A series of smaller flows to the NE known as the Crater Glass Flows were erupted at about the same time.

Photo by Lee Siebert, 1981 (Smithsonian Institution).

This image is made available under the Public Domain Dedication CC0 license, but proper attribution is appreciated.

Keywords: lava flow | stratovolcano | obsidian

Medicine Lake

Shasta