rift valley

rift valley
1. graben.
2. a subsea chasm extending along the crest of a mid-ocean ridge, locus of the magma upwellings that accompany seafloor spreading.
[1890-95]

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Elongated trough formed by the subsidence of a segment of the Earth's crust between dip-slip, or normal, faults.

Rift valleys are usually narrow and long and have a relatively flat floor. The sides drop away steeply in steps and terraces. Rift valleys are found on the continents and along the crests of oceanic ridges. They occur where two plates that make up the Earth's surface are separating (see plate tectonics). Submarine rift valleys are usually centres of seafloor spreading, where magma wells up from the mantle. The most extensive continental rift valleys are those of the East African Rift System; other notable examples include Russia's Baikal Rift Valley and Germany's Rhine Rift Valley.

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(Africa),also called  Eastern Rift Valley, or Great Rift System, 

      major branch of the East African Rift System (q.v.).

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Universalium. 2010.

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Look at other dictionaries:

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  • Rift Valley — GREAT RIFT VALLEY …   English World dictionary

  • rift-valley — see rift n.2 4 …   Useful english dictionary

  • rift valley — rift .valley n a valley with very steep sides, formed by the cracking and moving of the Earth s surface …   Dictionary of contemporary English

  • rift valley — rift ,valley noun count a valley with steep sides, produced when the land between two parallel cracks in the ground sinks …   Usage of the words and phrases in modern English

  • Rift valley — A rift valley is a linear shaped lowland between highlands or mountain ranges created by the action of a geologic rift or fault. This action is manifest as crustal extension, a spreading apart of the surface which is subsequently further deepened …   Wikipedia

  • rift valley — noun a valley with steep sides; formed by a rift in the earth s crust • Hypernyms: ↑valley, ↑vale • Instance Hyponyms: ↑Great Rift Valley * * * noun, pl ⋯ leys [count] geology : a long, steep valley formed when two parallel rifts form in the… …   Useful english dictionary

  • rift valley — UK / US noun [countable] Word forms rift valley : singular rift valley plural rift valleys a valley with steep sides, produced when the land between two parallel cracks in the ground sinks …   English dictionary

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