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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 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]
Shaded-relief map showing ridges of the Yakima Fold Belt of south-central Washington, mostly between Interstate 90 (red line) and the Columbia River (bottom). Red square in center is the city of Yakima, red rectangle at lower right is the Tri-Cities, red circles are various cities, triangles are the Mount Rainier, Mount St. Helens, and Mount Adams volcanoes of the Southern Washington Cascades.
A flood basalt (or plateau basalt [1]) is the result of a giant volcanic eruption or series of eruptions that covers large stretches of land or the ocean floor with basalt lava. Many flood basalts have been attributed to the onset of a hotspot reaching the surface of the Earth via a mantle plume . [ 2 ]
Chilcotin Plateau Basalts [e] Tortonian: 11.62 * Serravallian: 13.82 * Langhian: 15.97 M. Miocene disruption (14.8–14.5) [f] Columbia River Basalt Group [g] Chilcotin Plateau Basalts [e] Increased Antarctic deep waters Yellowstone hotspot Nördlinger Ries (14.5-14.3) Burdigalian: 20.44 Aquitanian: 23.03 * Shield volcanoes of Ethiopia [h ...
Aaron Clement Waters (1905–1991) was an American geologist, petrologist, and volcanologist, known for his pioneering work on the Columbia River Basalt. [ 1 ] Biography
The Touchet Formation was originally identified at the confluence of the Touchet River with the Walla Walla River. It is also found at some distance up the Touchet River Valley. The number of layers observed decreases as one progresses up-valley, indicating that the floodwater lakes varied in depth and distance upstream from the various flood dams.
The Alkali Canyon Formation is composed of basalt gravel and tuffaceous sediment. [3] The Alkali Canyon Formation overlies the Columbia River Basalt Group, a layer of flood basalt from the middle to late Miocene. [3] [better source needed] It underlies mainly Quaternary loess. [4]