Living in the shadow of some of the most majestic mountains in the Cascade Range, Dave Tucker became fascinated by both the beauty and danger of ancient volcanos.
As a kid raised in Pierce County, he could look out a window at home and see Mount Rainier.
Now, from a window at his house in Bellingham four decades later, he can stare at Mount Baker, a peak he’s become intimately acquainted with as a mountain climber and geologist.
“I came to geology late,” Tucker said during a talk at the Oak Harbor campus of Skagit Valley College Thursday night. “It wasn’t until 2001 at the ripe age of 51 that I went back to graduate school (at Western Washington University) to focus on geologic studies.
“Having an active volcano in my backyard, I decided I wanted to go to school and learn more about volcanos.”
Mount Baker is, indeed, active, Tucker told the group of about 30 people who filled a college classroom while he showed an image of the mountain from the vantage point he sees at home.
Tucker is now director of the Mount Baker Volcano Research Center and a research associate in the geology department at Western Washington.
“What you may not realize is gas plumes like this come out of Mount Baker 24 hours a day, seven days a week, and this has been going on for hundreds and hundreds of years, maybe thousands of years,” he said.
Still, the activity is nothing of anything seismic, unlike the tremors Tucker set off earlier in the day when he mistakenly wrote down the wrong time for his Oak Harbor talk. A capacity crowd of nearly 80 people showed up at the Oak Harbor Library for the advertised 3 p.m. talk about geology and Tucker’s new book, “Geology Underfoot in Western Washington” only to be informed he wouldn’t be arriving until 6.
Tucker apologized for the mishap and said he was working with the library to reschedule the talk there and added that he also hoped to do a talk in the future specifically about Mount Baker because of how prominently it appears and plays in the minds of those who live on Whidbey Island.
Tucker spent more than an hour talking mostly about his first book, which covers many of his experiences and most interesting finds collected during geological field trips all over Western Washington. The book, published by Mountain Press Publishing Company of Missoula, Mont., includes a chapter and several other references devoted to natural features on Whidbey.
A chapter on Whidbey is titled “Buried in Ice Repeatedly,” which points out how the island and Puget Sound took shape under the scouring of glaciers and the gravel, sand and rock deposits they left behind.
“The ice has advanced out of the interior of British Columbia and come down at least this far at least six times in the past million years or so,” Tucker said. “Most people just think of the last big ice age, but that ice age had at least six big glaciations and they’d leave behind deposits.”
Evidence is on display all over the island. Tucker points to the steep, eroding bluffs above the beach at Double Bluff in Freeland as an ideal site to see a record of the glacial and interglacial periods by different layers of sediments and terrestrial deposits.
“The significance is you can see deposits of more than one glaciation and you can see the interglacial deposits,” Tucker said. “Between those two glaciations, you can very easily see what’s called the Whidbey formation, which are mostly lake sediments and ponds and small streams very much like we have today that predates the most recent glacial advance out of British Columbia.
“You can walk the beach, and really lucky people will find fossil mammoth tusks. They erode off those bluffs and there they are. Some of those are on display in the geology museum at Western and down at the Burke Museum (in Seattle). They’re rare, but they’re found here.”
Other interesting geological finds on Whidbey are two prominent glacial erratics, or giant rocks that caught a ride on glaciers in Canada and were dropped off once the ice melted.
“We’re proud of our Coupeville rock,” one guest said.
She was referring to “Big Rock,” a 22-foot tall boulder covered in ivy behind the Coupeville Coffee and Bistro on Main Street. There is even a nearby apartment complex named after the rock.
“It needs a haircut,” Tucker said.
An even larger rock known as the “Waterman Erratic” is located in a forested area near Langley. It stands 38 feet tall.
“Those glaciers carried a lot of big rocks,” Tucker said. “Any place where you have glaciation, you will have erratics. If you really want to get down to it, the tiniest pebbles on the beach are erratics. But we don’t get excited about a cobble.”
Tucker was asked how Whidbey might fare in the event of a natural disaster such as a large earthquake that has been long predicted to strike the Puget Sound region. He pointed to the island’s mostly flat terrain as optimal in minimizing any impact.
“One of the things I mentioned in the Double Bluff chapter is there is an earthquake fault that runs through Whidbey there,” Tucker said. “It’s called the South Whidbey fault. It has the potential to be active to have earthquakes on it that could be magnitude 6 or magnitute 7.”
Tucker said disturbed young glacial sediments show evidence of a “pretty big” earthquake there within the past few thousand years.
And that brings up the topic of tsunamis in Puget Sound.
“The biggest tsunami threat is not so much from the big subduction zone earthquakes off the coast but from earthquakes along local faults like South Whidbey,” he said.
Tucker said he doesn’t get in the business of making any predictions and calls a couple thousand years “a blink of an eye” in geological time.
The eroding bluffs common to Puget Sound would take the biggest hit in relation to tsunamis, Tucker said, calling a portion of the west side of the island facing the Strait of Juan de Fuca most vulnerable should a large seismic event take place off the coast.
Tucker said there is evidence of past tsunamis in the lagoon across the street from beach-front homes in one stretch of West Beach Road near Joseph Whidbey State Park.
“That lagoon is filled with tsunami deposits,” he said. “Geologists know that those deposits are there. You don’t see them just walking around. You take a core ‘sample’ and you find tsunami deposits.”
“We don’t think they’re from 1700, the last big tsunami,” Tucker said. “The dates are low quality. It could be a thousand years old.”
As for Mount Baker, Tucker said the mountain doesn’t have a history of large eruptions nor does it act up often.
He said the last notable Mount Baker eruption occurred in 1843 and only involved steam blasts.
He said the mountain’s last large blast was 6,800 years ago, sending mudflows into the lowlands of Whatcom County.
“In terms of a Mount Baker eruption affecting people here on Whidbey, it would depend on the wind,” he said. “If the wind was coming out of the interior of British Columbia, you could get ash deposits here. Not much, but some. Up to an inch as a guess. Worst case scenario.”
Dave Tucker’s book, “Geology Underfoot in Western Washington” is in its second printing after selling out of its first 5,000 copies. It is for sale online as well as all as state and national parks.
