Sunday, February 19, 2012

Hiding in Plain Sight: The Snoqualamie River Channel

Here is an interesting article that is not related to schools, but I wanted to write it while the horse show tents are up at Marymoor Park.  It turns out that the photos don't capture what the eye sees, but once you know what you're looking for, you wonder why you didn't see it sooner. - Susan Wilkins
(note the arrow in the sky marking the channel )

The tents for the Cavalia Horse Show at Marymoor Park give us a good reference point for finding the ancient Snoqualmie River Channel. During the last Ice Age when the continental glacier from the north blocked the Snoqualmie Valley and the Strait of Juan de Fuca, water melting off the glaciers and out of the Cascade Mountains flowed over the large hill between the Snoqualmie Valley and Bear Creek Valley east of Redmond. We can see the channel if we look at the horizon to the right of the Cavalia Tents where the hillside appears to have a large bite taken out if it. This is what’s left of the ancient Snoqualmie River Channel.

At the time that the channel was in use, about 15,000 years ago, the downtown Redmond, Bear Creek and Sammamish Valley basins were filled by a great lake called Glacial Lake Russell. Lake Russell filled Puget Sound from the Olympics to the Cascades and all the way south to Olympia near the State Capitol Building. The surface elevation of Lake Russell was at 160 feet above sea level. The bottom of the Snoqualmie Channel that we see cut into the hillside hangs in the air at 160 feet above sea level because that is where the Snoqualmie River flowed into Lake Russell.

J. Harlen Bretz, the famous geologist who discovered the Missoula Floods in eastern Washington, visited Redmond in the early 1900s and recognized that the Snoqualmie River had once flowed across the hillside from the east and into the Sammamish Valley. He wrote about the Glacial Snoqualmie River in his 1913 classic, Glaciation of the Puget Sound Region.

Next time you drive down SR520 into Redmond, look for the Snoqualmie River. It’s up there, hiding in plain sight.

By Susan Wilkins
Redmond resident & frequent contributor
Photo by Wilkins

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