Ancient Driftwood

April 17, 2020

A large piece of three-hundred year old driftwood washed up on the beach in late March. Russ Lewis posted photos of it following one of his beach cleanup walks. I went out a few days later to see it in person. 

Kathleen took this photo of the root mass,
looking across the wood from the water side. Notice how flattened
it looks; the trunk and upper buttresses of roots have eroded away.
It is about 35 ft wide. 

This wood came ashore north of Oysterville Approach near the north end of Surfside Estates.  This is a large root mass of western red cedar, weathered off on top to expose the buttressed roots around the main trunk. 

The hole in the middle of this image is the heart of the original tree. 

There is an interesting hole on one side that may be the heart of the former tree. The mass is about 31 x 35 feet. From overhead, thanks to a drone photo taken by Bob Duke, we can see, large as this mass is, it is only a portion of the original basal root structure. [This image is posted on my Columbia Coast Natural History blog.] 

Bob Duke is the small figure at the bottom of this image, looking down
on the root mass with his drone. You can see that less than 40% of the
original root mass remains. The heartwood-hole is on the upper right side. 

Rockweed and green algae coated the saltwater edge of the root mass when it came ashore, which tells us that this root mass rested in salt water on the edge of a marsh. Historic root masses outcrop in several places around Willapa Bay and Grays Harbor, and are common on beach and marsh edges in these estuaries. The live algae and absence of gooseneck barnacles tell us that this root mass did not spend much time in the ocean. It washed out of its marsh and into the ocean, and up on the beach in just a few weeks. 

Another photo by Bob Duke shows the green algae growing on several roots

This photo by Kathleen shows the living rockweed on another root. These algae grew only on one side of the root mass--this was the side that was in salt water. 

For those who have followed Dr. Brian Atwater’s work on historic tsunamis on the Cascadia Subduction Zone, this driftwood material is familiar—it is a remnant of the lowland coniferous forests that covered this region prior to 1700, and which died due to subsidence and submergence in salt water after that event.  

Another photo by Bob shows the merging and dividing roots on one portion of the root mass.

Walk out and look at this driftwood while it’s still here—it’s a look back in time at a tree that died in the last subduction zone event.