Global Volcanism Program | Image GVP-08172
The snow-capped Sand Mountain scoria cones on the horizon were the source of the barren lava flow forming the far shore of Clear Lake. The lake formed when a series of lava flows erupted from the Sand Mountain volcanic field and traveled to the west, blocking the drainage of the ancestral McKenzie River. Standing stumps of the forest drowned by the rising lake waters have been radiocarbon dated to about 3,000 years ago and are still visible today.
Photo by Lee Siebert, 1999 (Smithsonian Institution).
This image is made available under the Public Domain Dedication CC0 license, but proper attribution is appreciated.