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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 ]
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]
It flows westward along the county line between Pitkin and Eagle County. Below Meredith, it is dammed to form the Ruedi Reservoir. It joins the Roaring Fork below Basalt. A portion of the river's water is diverted to the east side of the continental divide for irrigation and drinking water via the Fryingpan-Arkansas Project.
Basalt is distinguished from andesite by SiO 2 < 52%. Basalt is field B in the TAS classification. Vesicular basalt at Sunset Crater, Arizona. US quarter (24mm) for scale. Columnar basalt flows in Yellowstone National Park, US. Basalt is composed mostly of oxides of silicon, iron, magnesium, potassium, aluminum, titanium, and calcium.
Basalt columns seen on Porto Santo Island, Portugal. Columnar jointing of volcanic rocks exists in many places on Earth. Perhaps the most famous basalt lava flow in the world is the Giant's Causeway in Northern Ireland, in which the vertical joints form polygonal columns and give the impression of having been artificially constructed.
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 ...
Columnar jointing in Giant's Causeway in Northern Ireland Columnar jointing in the Alcantara Gorge, Sicily. Columnar jointing is a geological structure where sets of intersecting closely spaced fractures, referred to as joints, result in the formation of a regular array of polygonal prisms (basalt prisms), or columns.
The 500 cubic miles (2,100 km 3) of water in Lake Missoula was released in just 48 hours—a torrential flood equivalent to ten times the combined flow of all the rivers in the world. This mass of water and ice, 2,000 feet (610 m) high near the ice dam before release, flowed across the Columbia Basin, moving at speeds of up to 65 miles per hour ...