The Floating Island lava flow on the NNW flank of Mount St. Helens, named for an island of trees on the flow, has been dated to 1801 CE using tree-rings. This lava erupted shortly after the major explosive eruption of tephra layer "T" from a vent near the former Goat Rocks lava dome on the N flank. The Floating Island lava flow is now buried beneath the debris avalanche deposit from the 1980 eruption.

Photo by Rick Hoblitt, 1978 (U.S. Geological Survey).

This image is made available as a Public Domain Work, but proper attribution is appreciated.

Keywords: lava flow

St. Helens