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Continental Rift: Topography, Earthquakes and Volcanism

illustration of upper layers of the earth where they are being spread and thinned—under going continental rifting.

The Basin and Range topography develops over a few million years as fault lines move gradually, or more abruptly during tens of thousands of earthquakes. The colder upper crust cracks and breaks along faults (like peanut brittle), causing earthquakes and forming long mountains (ranges) separated by valleys (basins). Magma reaching the surface erupts from volcanoes and fissures as lava flows and other volcanic materials, mingling with river and lake sediments to fill rift valleys. Ripping a tectonic plate apart elevates the region and causes earthquakes, volcanic eruptions and the formation of long mountain ranges separated by broad valleys (basins).

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Modified from Beauty from the Beast: Plate Tectonics and the Landscapes of the Pacific Northwest,” by Robert J. Lillie, Wells Creek Publishers, 92 pp., 2015, www.amazon.com/dp/1512211893.

Public domain:Full Granting Rights

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Geologic Resources Division, Code: GRD

NPS.gov Collection

09/26/2019

09/26/2019

Wednesday, October 9, 2019 10:07:33 AM

Wednesday, October 9, 2019 10:07:33 AM

continental rift topography@10x.jpg

Thursday, September 26, 2019 2:52:36 PM

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1.8 MB

2019-09-26T08:52:36-06:00

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