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Flanking mountains are generally taller along the east side of the rift (although some of this relief may be Laramide in origin). [1] The thickness of the crust increases to the north beneath the rift, where it may be as much as 5 kilometres (3.1 mi) thicker than it is in the south. The crustal thickness underneath the rift is on average 30 ...
Quizlet is a multi-national American company that provides tools for studying and learning. [1] Quizlet was founded in October 2005 by Andrew Sutherland, who at the time was a 15-year old student, [ 2 ] and released to the public in January 2007. [ 3 ]
Cores taken from the plateau and other evidence shows that this area has been an undersea plateau for millions of years. [ 64 ] [ 65 ] Ancient indicators, i.e. relict beaches , marine deposits, and wave cut-terraces , of Pleistocene shorelines and sea level show that the Azores Islands have not subsided to any significant degree.
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]
The last glaciation did not cover this region (halting at the Des Moines terminal lobe mentioned above), so there is no glacial drift to form subsoils, giving the region the name of the Driftless area. As the topsoils are shallower and poorer than those to the west, dairy farming rather than cash crops is the principal agricultural activity.
In this case Yellowstone could be expiring. It could be another 1–2 million years (as the North American Plate moves across the Yellowstone hotspot) before a new supervolcano is born to the northeast, and the Yellowstone Plateau volcanic field joins the ranks of its deceased ancestors in the Snake River Plain. [12]
[1] [2] The Channeled Scablands were scoured by more than 40 cataclysmic floods during the Last Glacial Maximum and innumerable older cataclysmic floods over the last two million years. [ 3 ] [ 4 ] [ 5 ] These floods were periodically unleashed whenever a large glacial lake broke through its ice dam and swept across eastern Washington and down ...