Ice Age Natural History

Rocks, Bones, Water and Wonders


Geological historians agree that a series of Ice Age floods, bursting down from the Montana and Canadian border, over 15,000 years ago, define Tualatin’s geography and left lasting clues about prehistoric life here. The cataclysmic Ice Age Missoula Floods carried with them rich silt, resulting in the area’s fertile farmlands, as well as many huge boulders known as “glacial erratics.” (A glacial erratic is a piece of rock that differs from the size and type of rock native to the area in which it rests.) Among the glacial erratic  that were tossed along with the pre-historic rushing waters include a 20,000 lb. granite boulder and 5,500 lb quartz rock, both unearthed from local farms in recent years, and now displayed in front of the Tualatin Historical Society. With other geological artifacts and information, they tell the story of the Tualatin landscape.

Inspired by these many exciting and notable geological findings, the city is developing an Ice Age walk that will link Tualatin’s many paleontological landmarks with informative exhibits.   It will connect with the city’s existing Art Walk.

Tualatin Mastodon Bones

To learn the story of prehistoric wildlife, stop by the Tualatin Library, where you can see the “Tualatin Mastodon,” the 12,000-year old skeleton unearthed in the 1960’s by two Portland State University students at a site near the present Fred Meyer Shopping Center.   A huge elephant-like woodland browser, mastodon’s grazed throughout the area forests and meadows.   Other findings include proof of sloths, bison and other unusual creatures that once roamed the dense landscape.

Learn More about Tualatin Mastdon’s History

Learn More about Tualatin’s History