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The lateral extent of a flood basalt flow is roughly proportional to the cube of the thickness of the flow near its source. Thus, a flow that is double in thickness at its source can travel roughly eight times as far. [13] Flood basalt flows are predominantly pāhoehoe flows, with ʻaʻā flows much less common. [39] Eruption in flood basalt ...
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]
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.
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.
Kilbourne Hole (center) and Hunt's Hole (lower right), with White Sands National Park lit by the sun in the distance beyond the Organ Mountains Basalt cliffs of Kilbourne Hole, looking northwest from near the southwest corner. The cliffs come from the earlier Cenozoic Afton basalt flow; the magma that caused the maar explosion was also basalt. [1]
Basalt (UK: / ˈ b æ s ɒ l t,-ɔː l t,-əl t /; [1] [2] US: / b ə ˈ s ɔː l t, ˈ b eɪ s ɔː l t /) [3] is an aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the surface of a rocky planet or moon.
During late Miocene and early Pliocene times, a flood basalt engulfed about 63,000 square miles (160,000 km 2) of the Pacific Northwest, forming a large igneous province. [2] Over a period of perhaps 10 to 15 million years, lava flow after lava flow poured out, ultimately accumulating to a thickness of more than 6,000 feet (1.8 km). [2]
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.