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Channeled Scablands and Potholes

The epoch floods from glacial Lake Missoula repeatedly scoured the landscape throughout much of eastern Washington between 13,000 and 15,000 years ago. Topographic features large and small were created. Large coulees (canyons) were carved out of the many layers of basalt. The Grand Coulee and Moses Coulee are examples.

The floods also helped create more subtle landforms: biscuit and swale topography and vernal ponds. The biscuit and swale topography consists of relatively low, predominantly grass-covered mounds (a few feet high by a few meters in diameter) interspersed in a mosaic with ground that is dominated by fist-sized basalt rocks, with a more sparse vegetative cover.

Vast numbers of vernal pools are scattered throughout the channeled scablands. These pools fill up with water or snow during the winter, but then dry up by early to mid-summer. Not surprisingly, they have their own characteristic flora. They may also have a unique faunal component, although the vernal pools in Washington have not been well-studied to date.

Ecological Systems of Washington's Scablands

Columbia Plateau Scabland Shrubland

Columbia Plateau Vernal Pool

Northern Columbia Plateau Basalt Pothole Ponds

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