Evolution of the Puget Lowland, last 20,000 years

Animation of the advance and retreat of the last great glaciation in the Puget Lowland is available on the Burke Museum’s YouTube channel. Thanks to reader ‘Deb’ who notified me that the link in the ‘Lake Stevens Erratic- the largest in the US?’ page was broken. It’s been repaired. The animation is based on a model by Ralph Haugerud of the USGS- see the very end of the animation for full credits. Unfortunately, the model is only for Puget Sound, and does not include the San Juan Islands or points north. The source of the glacial lobe is not shown- the interior of British Columbia, the BC Coast Mountains, and the Canadian Rockies. The diagram shows the bigger picture, which has a chapter on glacial erratics, and another on the history of glaciations in the lowlands of western Washington.


Diagram from my book,Geology Underfoot in Western Washington showing sources and paths of ice related to the Vashon Lobe. The glacial tongue reached its maximum extent south of Olympia around 16,000 years ago.

This animation is a bit different from the original. This one shows events in the Lowlands following retreat of the Vashon glacial lobe, such as the Osceola Lahar from Mount Rainier 5600 years ago that reached the salt water Duwamish Embayment near Auburn, and local rebound of the crust from the weight of the ice.

If anyone finds broken links anywhere on this website. please notify me by way of a comment on the page. If you know if a replacement link, please include that.