Ice Age Glacial Erratics

Coulee City, Washington

Along Hwy 2 between Coulee City and Waterville

Driving west on Highway 2 out of Coulee City, you may notice a handful of very large basalt boulders (some bigger than houses) that seem out of place in some wheat fields. These rocks didn't just roll down some hill to end up here. They were carried here and deposited during the Ice Age.

During the Ice Age, the Okanogan Lobe of the Cordilleran Ice Sheet blocked the natural flow of water down the Columbia River and creating a lake of meltwater between the ice lobe and the Waterville plateau. Large basalt rocks that had been trapped in glacier ice. As chunks of ice broke off the glacier to become ice bergs in this lake, the bergs sometimes carried the boulders with them. As the bergs melted, they dropped their rocks to the bottom of this lake, now the top of the Waterville Plateau.

Today the Waterville Plateau is high and dry - and in places it is littered with large basalt glacial erratics. Highway 2 between Coulee City and Waterville passes through this area.


coulee city ice age glacial erratic

Ice Age Glacial Erratic (C14A2278)

Nearby Sights

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