In geology, a rift is a place where the Earth's crust and lithosphere are being pulled apart. Typical features are a central linear downdropped fault segment, called a graben, with parallel normal faulting and rift-flank uplifts on either side forming a rift valley. The axis of the rift area commonly contains volcanic rocks and active volcanism is a part of many but not all active rift systems. Rifts are distinct from Mid-ocean ridges, where new oceanic crust and lithosphere is created by seafloor spreading. In rifts, no crust or lithosphere is produced. If rifting continues, eventually a mid-ocean ridge may form, marking a divergent boundary between two tectonic plates. Failed rifts, which may be ancient or modern, are where continental rifting began, but then failed to continue. Typically the transition from rifting to spreading develops as three converging rifts over a hotspot. Two of these evolve to the point of seafloor spreading, while the third ultimately fails, becoming an aulacogen.
Examples
- Great Rift Valley in Africa
- Red Sea
- Lake Baikal, the bottom of the lake is the deepest continental rift on the earth.
- Lake Timiskaming in Temiskaming Shores, Ontario
- 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
- The Taupo Volcanic Zone in the north east North Island of New Zealand
- The Oslo Graben in Norway
- The Ottawa-Bonnechere Graben in Ontario
- The Northern Cordilleran Volcanic Province in British Columbia, Yukon and Alaska
- The West Antarctic Rift in Antarctica
- Midcontinent Rift System, a late Precambrian rift in central North America
