From Washington To You
Dead western red cedar snags standing in a tidal marsh at the Copalis River.
Photograph by Brian Atwater, U.S. Geological Survey. Public domain.

From Washington to you

Copalis Ghost Forest

Copalis River ghost forest · Grays Harbor County · January 26, 1700

Western red cedars at the Copalis River died between the 1699 and 1700 growing seasons — killed when Cascadia dropped the coast.

A dead forest of western red cedar stands in a brackish tidal marsh on the Copalis River. USGS says the trees were killed by rapid subsidence during the most recent Cascadia megathrust earthquake. Tree rings show they died sometime after the end of the A.D. 1699 growing season and before the beginning of the A.D. 1700 growing season.

That timing matches a tsunami recorded in Japanese historical records. USGS Fact Sheet 2025-3050 dates the last great Cascadia earthquake to January 26, 1700, with an estimated magnitude between 8.7 and 9.2. Living forest behind the snags stands above the highest tides.

The photograph below is by Brian Atwater of the U.S. Geological Survey. The sources below are USGS pages.

  • Geography & Geology
  • Science / Strange Washington

Sources (2)

Last reviewed: September 21, 2026

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