New Ghost Forest on S. Oregon Coast Remains of 1700 Megathrust Quake, Tsunami

Published 03/09/21 at 6:30 PM PDT
By Oregon Coast Beach Connection staff

(Coos Bay, Oregon) – There may well be a new ghost forest in the mix of those already documented along the Oregon coast, and this time it has an origin many are already familiar with. Even if they’re familiar with it for the wrong reasons. They, in turn, lead to a fascinating journey through other kinds of ghost forests on the coastline – not just those on the beaches. (All photos courtesy Brent Lerwill)

Coos Bay resident and CoastWatch volunteer Brent Lerwill brought them to the attention of Oregon Coast Beach Connection after he assisted on a recent story digging into the Sunset Bay ghost forest. The Unheralded Ghost Forests of South Oregon Coast / Coos Bay in Photos 

Lerwill said they’re actually below his property, about 100 feet down, but they’re in a truly hidden place that you can only get to via kayaking.

“They’re on the south shore of Brown's Cove, South Slough,” he said. “This is about one mile south of the Charleston bridge and south of Indian Point. I don't know if these roots are ancient or anything about them, except they have a similar appearance to the ones at Sunset Bay.”

So began another investigation.

After contacting a number of geologists, Seaside’s Tom Horning was the first to head down the right path. He said they looked like ghost forests from the 300-year-old tsunami that hit the Pacific Northwest, the “big one” from 1700, which other media have erroneously said caused the ghost forests in the sands of the coastline. The estuaries of the Oregon coast are full of these from the 1700 mega thrust quake and tsunami, and they’re full of tsunami-created ghost forests that are much older as well. But it’s important to remember that the stumps found on sandy beaches are not from a quake dropping the ground suddenly and then causing a tsunami. Those are another story.

Next came word from Coos Bay geologist Ron Metzger, who confirmed what Horning said.

“Looks similar to the row of stumps down at the Bandon Marsh from the 1700 event,” Metzger said.

It's not 100 percent of an ID on these, but it's almost competely positive.

He said he’d brought another geologist to Bandon decades ago, who was researching inland / estuary ghost forests from the 1700 subsidence event.

“We went upstream a little ways from Hinch Road bridge in South Slough and dug out/exposed a tsunami sand sample from the 1700 event with Tom Gaskill (we collected a sample to display at the South Slough Visitor Center),” Metzger said. “If memory serves there were also roots/stump likely from 1700 event as well.”

Part of how they know about these stumps is checking out the soil around them. Then you can find evidence of “tsunami sands.”

Lerwill’s ghost forest stumps don’t appear to be documented anywhere else, and definitely not in the 2006 Roger Hart / Curt Peterson paper on ghost forests that essentially proved what beach stumps really were – that they were a slower process and not a subsidence event like their inland cousins. So this means the Coos Bay estuary stumps are a new one – and Oregon Coast Beach Connection has named them “Lerwill’s Forest,” in honor of his essentially finding them.

There are essentially three kinds of ghost forests: those in the sand, those sticking out of exposed cliffs, and those in the estuaries. Stumps in the sands and cliffs came from the slow process called encroachment. Those are 1,000 to 7,000 years old. See Explanations of Neskowin Ghost Forest Wrong, Say Oregon Coast Geologists

Estuary stumps – and every coastal estuary has them – come in different ages as well, according to Horning. Some have them from different millennia events, thousands and thousands of years old at times. This is a big revelation to many coastal fans: there are many more ghost forests than people know about.

How to find them?

According to PSU geologist Dr. Scott Burns: “You just have to stand on 101 and look. That is what I do.”

They admittedly aren't as interesting to look at: they look like rather newish stumps and simple logs lying around, not with the craggy shapes and encrusted surfaces we’re used to seeing on the beaches.

Horning lives along the Seaside estuary and has them as well.

“My ghost forest is not very impressive, since most of the stumps have rotted away, leaving just the roots and a bit of flair where the main part of the stump joined the roots,” Horning said. “There are similar 1700 AD forests up and down the coast, including along the north side of Ecola Creek.”

Meanwhile, Lerwill’s Forest down south in Coos Bay does a look a little more ragged and ghosty than the average 300-year-old stumps. Whatever the condition of estuary stumps you find, it’s interesting and eerie to know they’ve been through a terrible, cataclysmic event that took out maybe a mile inland worth of beach landscape.

It’s also important to learn from these: this same kind of quake is coming to the Pacific coast someday again.

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