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

Initially, the sea was a narrow rift valley filled with lakes, then became a wider gulf when it was flooded from the Mediterranean 23 million years ago.

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The polar environment at that time was a rift valley with braided rivers.

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One of Iceland’s most popular tourist destinations, the park lies in a rift valley that marks the crest of the Mid-Atlantic Ridge and the boundary between the North American and Eurasian tectonic plates.

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They also include rift valley fever, common in sub-Saharan Africa, along with Mers and Sars – respiratory diseases that are caused by coronaviruses and have far higher death rates than Covid-19 but are less infectious.

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The rift valley results from an upwelling of magma in the Earth’s mantle that is slowly splitting the continent of Africa in two.

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