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Learn more about Oregon's geology


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Deschutes-Columbia Plateau

Between 14 and 16 million years ago, "fissure" volcanic eruptions in eastern Washington, eastern Oregon, and western Idaho produced enormous volumes of molten Columbia River basalt that flowed like water west into the Deschutes-Columbia Plateau province in eastern Washington and northeastern Oregon, with some lava continuing to flow as far west as the Pacific Ocean via the ancestral Columbia River valley. As the basalt cooled and congealed, it formed the columnar cliffs that dominate the landscape today. Erosions by the Columbia River has exposed a particularly spectacular sequence of these rocks in the Columbia River Gorge on Oregon’s northern boundary.

Links:
Oregon Outdoors
John Day Fossil Beds
Lake Billy Chinook and Cove Palisades State Park,
Deschutes - Ochoco National Forests


map legendCoastal RangeKlamath MountainsDeschutes-Columbia PlateauBlue MountainsHigh Lava PlainsCascade RangeWillamette ValleyBasin & Range & Owyhee uplandsBasin & Range & Owyhee uplands

Graphic by Elizabeth L. Orr, Geology of Oregon,
available from Nature of the Northwest


map legendaBlue MountainsWillamette ValleyDeschutes-Columbia plateauKlamath MountainsCoast Rangemap legendbCascade MountainsBasin Range & Owyhee uplandsHigh Lava plainsOwyhee UplandsCascade MountainsBasin & Range & Owyhee UplandsHigh Lava PlainsOwyhee UplandsCascade MountainsBasin & Range & Owyhee UplandsHigh Lava PlainsOwyhee UplandsCascade MountainsBasin & Range & Owyhee UplandsHigh Lava PlainsOwyhee UplandsCascade MountainsBasin & Range & Owyhee UplandsHigh Lava PlainsOwyhee Uplands


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Formations of columnar basalt
Formations of columnar basalt can be found throughout the Plateau.

Clarmo unit of John Day
The Clarmo Unit of the John Day Fossil Beds sits on the southern edge of the Plateau.

Oregon Paleo Project



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