rift valley

noun Geology.

a subsea chasm extending along the crest of a mid-ocean ridge, locus of the magma upwellings that accompany seafloor spreading.

Origin of rift valley

First recorded in 1890–95

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Examples from the Web for rift valley

Historical Examples of rift valley

The older group commenced with a series of fissure eruptions along the site of the present rift-valley and parallel with it.
Encyclopaedia Britannica, 11th Edition, Volume 4, Part 3
Various
This great volcanic period was followed by the eruptions of Kibo and some of the larger volcanoes of the rift-valley.
Encyclopaedia Britannica, 11th Edition, Volume 4, Part 3
Various

British Dictionary definitions for rift valley

rift valley

noun

a long narrow valley resulting from the subsidence of land between two parallel faults, often associated with volcanism. The East African Rift Valley is an example

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

rift valley in Science

rift valley

A long, narrow valley lying between two normal geologic faults. Rift valleys usually form where the Earth's lithosphere has become thin through extension associated with plate-tectonic processes. Unlike river valleys and glacial valleys that form primarily through erosional processes, rift valleys form by the subsidence of the intermediate land as the faults are pulled apart. They are on the order of thousands of kilometers long and wide. See more at normal fault.

The deep undersea valley located along the center of the mid-ocean ridge. It is associated with the crustal thinning and extensional forces that cause magma to upwell onto the ocean floor.