rift valley

noun

, Geology.

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

rift valley

noun

1. 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

rift valley

1. 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.
2. See more at normal fault
3. 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.

Word History and Origins

Origin of rift valley¹

First recorded in 1890–95

Example Sentences

The older group commenced with a series of fissure eruptions along the site of the present rift-valley and parallel with it.

From Project Gutenberg

This great volcanic period was followed by the eruptions of Kibo and some of the larger volcanoes of the rift-valley.

From Project Gutenberg

Far below, bathed in sunshine, stretching away to misty purple horizons, lie the broad expanses of the Rift Valley.

From Project Gutenberg

There are also many up in the Rift Valley and doubtless in other sections.

From Project Gutenberg

A deep narrow gorge, the so-called “eastern rift-valley,” traverses the middle of the plateau in a meridional direction.

From Project Gutenberg