Ice Age Tonquin Trail

January 4, 2013

I’m always on the lookout for unique, interesting recreation that blends adventure with history and tells a really good story along the way. So imagine a time – not so long ago – when gigantic icebergs floated across an incredible lake that flooded the entire broad-shouldered Willamette Valley. Now, it’s history you can explore along a Portland Metro-area hiking trail called the Ice Age Tonquin Trail.


If you want to connect adventure and Oregon history, West Linn’s Fields Bridge Park is a good place to start. I recently joined historian Rick Thompson, who explained how 46,000 pounds of granite boulders called “erratics” came to rest along the trail. Thompson is an Ice Age flood expert who created a map for the park that tells the “erratic” story: a time when massive and successive Ice Age floods of water and icebergs loaded with granite boulders roared down the gorge and through the valley as far south as Eugene.

He said that the resulting Lake Allison was nearly 400 feet deep and his map shows where it reached in the valley. “I traced the four-hundred-foot level all the way down to Eugene, drawing all the nooks and crannies where smaller valleys would have filled with water. The lake affected the entire layout of the Northwest; it’s why there’s a shape to the Willamette Valley and the Portland basin.”

Now, that ancient story is as close and relevant as many Portland area neighborhoods on the new Ice Age Tonquin Trail. You can join the trail at the new Graham Oaks Nature Park in Wilsonville.

Jane Hart is Metro’s manager of the Ice Age Tonquin Trail project and she said that the 22-mile trail will link Wilsonville, Sherwood and Tualatin. Eventually, the new trail will put hikers and cyclists right in the middle of ice age history.“It’s a hard surface trail that is wide and accommodates all kinds of uses and people who are in wheelchairs. The trail will travel through a varied landscape that goes up and down and is hilly in some places. It will also wind through natural areas. It’s true value is a connection to nature that people hold dear to their hearts in Oregon.”

Nearby, the city of Tualatin is on the fast track to embrace the Ice Age theme, according to the city’s Paul Hennon. He said the Tualatin Heritage Center and the city library display a mastodon tusk and a full-sized skeleton. Both were found in nearby farmland.

Hennon added that the new trail will allow hikers to see Tualatin’s Koller Kolk Pond, which was created 15,000 years ago when bedrock was scoured out by the glacial floods and exposed the pond’s surrounding basalt rock cliffs. “Visitors will see and touch and learn about the effects of the Ice Age floods in Tualatin, and also about the prehistoric mammals that roamed the entire Willamette Valley. These floods created land forms that are now significant parts of the valley and they were the largest on Earth, so understanding that history helps create a sense of place for people,” Hennon said.

So far, four miles of the Ice Age Tonquin Trail have been paved for recreational use and that includes the nearby Ki-a-Kuts Bridge. The bridge was completed in 2007 and links Tualatin with Durham and the Fanno Creek Trail, which reaches all the way to Beaverton. Metro Councilor Carl Hosticka said that the new Ice Age Tonquin Trail will likely take years to complete, but so far the neighbors are proud of what’s been done. “Trails and parks! That’s what people really like and it’s what makes the Portland metro area different from other metro areas. We have a unique network of parks and trails integrated with our urban environment,” he said.

Near Sherwood, that urban environmental experience really comes to life for hikers who take a winter stroll through the Tualatin River National Wildlife Refuge where ducks, geese and bald eagles rule the vast wetland. “The refuge is expansive,” said Hart. “You can see forever and it’s a timeless landscape. The refuge’s connection with the Ice Age Tonquin Trail makes it really easy to transport yourself back in time. I think the refuge will help people get that message.”

The new Ice Age Tonquin Trail promises to put you in touch with the great Oregon outdoors and teach you something special about our state’s remarkable story.

About The

Grant McOmie
Grant McOmie is a Pacific Northwest broadcast journalist, teacher and author who writes and produces stories and special programs about the people, places, outdoor activities and environmental issues of the Pacific Northwest. A fifth generation Oregon native, Grant’s roots run deepest in the central Oregon region near Prineville and Redmond where his family continues to live.