Global Volcanism Program | Image GVP-03108
The Rock Mesa lava flow in the foreground erupted from a vent on the SW flank of South Sister volcano about 2,300 years ago. Emplacement of the lava flow was the final stage of an eruption that began with strong explosions accompanied by pyroclastic flows and surges.
Photo by Lyn Topinka, 1985 (U.S. Geological Survey).
This image is made available as a Public Domain Work, but proper attribution is appreciated.