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The Columbia River Basalt Group (including the Steen and Picture Gorge basalts) extends over portions of four states. The Columbia River Basalt Group (CRBG) is the youngest, smallest and one of the best-preserved continental flood basalt provinces on Earth, covering over 210,000 km 2 (81,000 sq mi) mainly eastern Oregon and Washington, western Idaho, and part of northern Nevada. [1]
The Columbia Plateau is an important geologic and geographic region that lies across parts of the U.S. states of Washington, Oregon, and Idaho. [1] It is a wide flood basalt plateau between the Cascade Range and the Rocky Mountains , cut through by the Columbia River .
The Ringold Formation represents sand and gravel placed by the Columbia River between 9 and 3 million years ago. These deposits overlay cooled lava erupted as part of the Columbia River Basalt Group, a type of volcanic eruption known as flood basalts erupting from fissures across eastern Washington and Oregon that were unrelated to the Cascade Range. [11]
The canyon at the falls is 377 feet (115 m) deep, exposing a large cross-section of the Columbia River Basalt Group.These falls and the canyon downstream are an important feature of the channeled scablands created by the great Missoula floods that swept periodically across eastern Washington and across the Columbia River Plateau during the Pleistocene epoch.
Columbia River Basin. Wallula Gap (/ w ə ˈ l uː l ə /) is a large water gap of the Columbia River in the Northwestern United States, in Southeastern Washington.It cuts through the Horse Heaven Hills basalt anticlines in the Columbia River Basin, just south of the confluence of the Walla Walla and Columbia rivers.
The earliest Snake River Plain eruptions began about 15 million years ago, just as the tremendous early eruptions of Columbia River Basalt were ending. But most of the Snake River Plain volcanic rock is less than a few million years old, Pliocene age (5–1.6 million years ago) and younger. [8]
The Touchet Formation or Touchet beds consist of well-bedded, coarse to fine sand and silt which overlays local bedrock composed of Neogene basalt of the Columbia River Basalt Group in south-central Washington and north-central Oregon.
The top exposed layer of Columbia River Basalt Group basalt in the Saddle Mountains is the Saddle Mountain Basalt, which ranges from 120 – 240 meters (400 – 800 feet) in thickness and is interspersed by sedimentary layers of the Ellensburg Formation. The Saddle Mountain Basalt is composed of the Umatilla Member flows, the Wilbur Creek ...