Unuk River waterfalls from old lava pipes
Unuk River waterfalls from old lava pipes. Volcanic lava pipes form as the result of violent eruptions of deep-origin volcanoes. The Unuk River is one of the transboundary watersheds of Southeast Alaska. Visit USGS Transboundary River Monitoring in Southeast Alaska for more information about our research.
Photo by Jennifer Hamblen, U.S. Geological Survey