In the vast Willamette Valley—with a little imagination—you can travel into a turbulent and tumultuous chapter of geologic history, when gigantic icebergs carried by floodwater that was more than four hundred feet deep floated across the broad-shouldered valley.
It may be hard to believe, but it’s true! In the blink of a geologic eye, a series of tremendous floods occurred, perhaps twenty times every fifty years for two thousand years–beginning nearly fourteen thousand years ago near the end of the Ice Age.
Gigantic, glacial Missoula Lake (in what is now Montana), backed up by an ice dam several miles wide and half a mile high, burst through its western wall and raced across the plains and valleys between Montana and the Pacific Ocean.
Geologists say some five hundred cubic miles of floodwater and icebergs roared across the Northwest, carrying away anything and everything in its path. As the ice flowed, it broke into thousands of pieces, and many of the pieces ended up stranded along the flood route.
These “erratics”–a geological term that describes a rock found a considerable distance from its place of origin–range from pebble- to baseball- to car-size boulders that still dot the Willamette Valley.
Near present-day Sheridan, off Oregon 18, one giant berg melted and tipped its load, a massive rock that is called the Belleview Boulder. It is the centerpiece of Erratic Rock State Natural Site and rests on the shoulder of a hillside overlooking the highway. As you hike, notice the gently rolling landscape of the surrounding vineyard-laden hillsides. This landscape is a stark contrast to the Belleview Boulder!
Notice the smoothed edges and scratches across the boulder’s surface and its sharp angles compared with the rest of the valley. It is a fine place for a picnic lunch and a pause to consider so much dramatic history.
There’s more geologic drama based at one of the most interesting historic homes of the Portland area; a home that houses one of the most magnificent collection of rocks and minerals in the region. The Rice NW Museum of Rocks and Minerals has been a drawing card for rock hounds for more than forty years – it provides even the casual visitor a stunning visual treat.
Editor’s Note: Grant’s Getaways is a production of Travel Oregon brought to you in association with Oregon State Parks, Oregon Dept. of Fish & Wildlife and Oregon State Marine Board. Episodes air Fridays and Saturdays on KGW Newschannel 8 and Saturdays on Northwest Cable News Network.