Rift (geology) - Definition and Overview

In geology, a rift is a place where the Earth's lithosphere is expanding. Typical features are a central linear downdropped fault segment, called a graben, with parallel normal faulting on either side. The central portion of the rift area commonly contains volcanic rocks and active volcanism is a part of active rift systems. Rifts are located at divergent boundaries between two tectonic plates. Between oceanic plates the rifts occur as oceanic ridges and where these oceanic ridges intersect continental crust rift valleys result as the continent begins to split. Failed rifts are ancient to modern features where continental rifting began, but then failed to continue.

Examples of rifts include:

• Great Rift Valley in Africa
• Mid-Atlantic Ridge
• throughout the Basin and Range Province in North America
• the Rio Grande Rift in the southwestern US.
• the rift in the middle of the Gulf of Corinth in Greece
• The Reelfoot Rift, an ancient buried failed rift underlying the New Madrid Seismic Zone in the Mississippi embayment.

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