Rift

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Rift

In geology

Geology

Geology is the science and study of the solid and liquid matter that constitute the Earth. The field of geology encompasses the study of the composition, structural geology, physical properties, dynamics, and History of the Earth of Earth materials, and the processes by which they are formed, moved, and changed....
, a rift is a place where the Earth

Earth

Earth is the third planet from the Sun. Earth is the largest of the terrestrial planets in the Solar System in diameter, mass and density. It is also referred to as the World and Wiktionary:Terra.Note that by International Astronomical Union convention, the term "Terra" is used for naming extensive land masses, rather...
's crust

Crust (geology)

In geology, a crust is the outermost solid shell of a planet or moon, which is chemically distinct from the underlying mantle . Crusts of Earth , our Moon, Mercury , Venus, and Mars have been generated largely by igneous processes, and these crusts are richer in incompatible elements than their respective mantle s....
and lithosphere

Lithosphere

File:Plates tect2 en.svgFile:Earth-crust-cutaway-english.svgThe lithosphere is the rigid outermost shell of a rocky planet....
are being pulled apart and is an example of extensional tectonics

Extensional tectonics

Extensional tectonics is concerned with the structures formed, and the tectonic processes associated with, the stretching of the Crust or lithosphere....
.

Typical rift features are a central linear downdropped fault

Geologic fault

In geology, a fault or fault line is a planar Fracture in rock in which the rock on one side of the fracture has moved with respect to the rock on the other side....
segment, called a graben

Graben

A graben is a depression block of land bordered by parallel Fault s. Graben is German language for ditch.A graben is the result of a block of land being downthrown producing a valley with a distinct Escarpment on each side....
, with parallel normal faulting and rift-flank uplifts on either side forming a rift valley

Rift valley

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In geology

Geology

Earth

Crust (geology)

Lithosphere

File:Plates tect2 en.svgFile:Earth-crust-cutaway-english.svgThe lithosphere is the rigid outermost shell of a rocky planet....
are being pulled apart and is an example of extensional tectonics

Extensional tectonics

Geologic fault

In geology, a fault or fault line is a planar Fracture in rock in which the rock on one side of the fracture has moved with respect to the rock on the other side....
segment, called a graben

Graben

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 by the forces of erosion....
, where the rift remains above sea level. The axis of the rift area commonly contains volcanic rocks and active volcanism is a part of many, but not all active rift systems.

Most rifts occur along the central axis of a mid-ocean ridge

Mid-ocean ridge

A mid-ocean ridge or mid-oceanic ridge is an underwater mountain range, typically having a valley known as a rift running along its spine, formed by plate tectonics....
, where new oceanic crust

Oceanic crust

Oceanic crust is the part of Earth's lithosphere that surfaces in the ocean basins. Oceanic crust is primarily composed of mafic rocks, or Sima ....
and lithosphere is created along a divergent boundary

Divergent boundary

In plate tectonics, a divergent boundary or divergent plate boundary is a linear feature that exists between two List of tectonic plates that are moving away from each other....
between two tectonic plate

Tectonic Plate

#REDIRECT Plate tectonics...
s.

Failed rifts are where continental rifting began, but then failed to continue to the point of break-up. Typically the transition from rifting to spreading develops at a triple junction

Triple junction

A triple junction is the point where the boundaries of three tectonic plates meet. At the triple junction a boundary will be one of 3 types - a Mid-ocean ridge, oceanic trench or transform fault and triple junctions can be described according to the types of plate margin that meet at them....
where three converging rifts meet over a hotspot

Hotspot (geology)

In geology, a hotspot is a location on the Earth's surface that has experienced active volcano for a long period of time. J. Tuzo Wilson came up with the idea in 1963 that volcanic chains like the Hawaiian Islands result from the slow movement of a tectonic plate across a "fixed" hot spot deep beneath the surface of the planet....
. Two of these evolve to the point of seafloor spreading, while the third ultimately fails, becoming an aulacogen

Aulacogen

In geology, an aulacogen is a failed arm of a triple junction of a plate tectonics rift system. A triple junction beneath a continental plate initiates a three way breakup of the continental plate....
.

Examples

The East African Rift
East African Rift

The East African Rift is part of the larger Great Rift Valley. It is a continental rift zone that appears to be a developing Divergent boundary....
The Red Sea Rift
Red Sea Rift

The Red Sea Rift is a spreading center between two tectonic plates, the African Plate and the Arabian Plate. It extends down the length of the Red Sea, stretching from the southern end of the Dead Sea Transform to a triple junction with the Aden Ridge and the East African Rift in the Afar Depression of eastern Africa....
The Baikal Rift Zone
Baikal Rift Zone

The Baikal Rift Zone is a divergent plate boundary centered beneath Lake Baikal in southeastern Russia. To its west is the Eurasian Plate and to its east is the Amur Plate which is moving away from the rift toward Japan at about 4 mm per year....
, the bottom of Lake Baikal
Lake Baikal

Lake Baikal is in southern Siberia in Russia, located between Irkutsk Oblast to the northwest and the Buryatia to the southeast, near the city of Irkutsk....
is the deepest continental rift on the earth.
The Gulf of Suez Rift
Gulf of Suez Rift

The Gulf of Suez Rift is a continental rift zone active between the Late Oligocene and the end of the Miocene . It represented a continuation of the Red Sea Rift until break-up occurred in the middle Miocene, with most of the displacement on the newly developed Red Sea Mid-oceanic ridge being accommodated by the Dead Sea Transform....
Lake Timiskaming
Lake Timiskaming

Lake Timiskaming is a large freshwater lake on the Provinces and territories of Canada border between Ontario and Quebec, Canada. The lake, which forms part of the Ottawa River, is in length and covers an area of almost ....
in Temiskaming Shores, Ontario
Ontario

Ontario is a Provinces and territories of Canada located in the Central Canada part of Canada, the largest by population and second largest, after Quebec, in total area....
Throughout the Basin and Range Province in North America
North America

North America is the northern continent of the Americas, situated in the Earth's northern hemisphere and almost totally in the western hemisphere....
The Rio Grande Rift
Rio Grande Rift

The Rio Grande rift is a rift valley extending north from Mexico, near El Paso, Texas through New Mexico into central Colorado. The upper Rio Grande flows south down the rift valley, but did not incise the rift valley....
in the southwestern US
The rift zone that contains the Gulf of Corinth
Gulf of Corinth

The Gulf of Corinth or the Corinthian Gulf is a deep inlet of the Ionian Sea separating the Peloponnese from western mainland Greece. It is bounded in the east by the Isthmus of Corinth which includes the shipping route of the Corinth Canal, and in the west by the Strait of Rion, which separates the Gulf of Corinth from the oute...
in Greece
Greece

Greece , officially the Hellenic Republic , is a country in southeastern Europe, situated on the southern end of the Balkans. It has borders with Albania, Bulgaria and the former Yugoslav Republic of Macedonia to the north, and Turkey to the east....
The Reelfoot Rift, an ancient buried failed rift underlying the New Madrid Seismic Zone
New Madrid Seismic Zone

The New Madrid Seismic Zone, also known as the Reelfoot Rift or the New Madrid Fault Line, is a major seismic zone in the Southern United States and Midwestern United States stretching to the southwest from New Madrid, Missouri, Missouri....
in the Mississippi embayment
Mississippi embayment

The Mississippi embayment is a physiographic feature in the south-central United States, part of the Mississippi Alluvial Plain. It is essentially a northward continuation of the River delta of the Mississippi River Delta to its confluence with the Ohio River at Cairo, Illinois....
The Rhine Rift
Rhine rift

The Upper Rhine valley describes the Upper Rhine area on the earth's surface, while the Upper Rhine Rift is the geological formation below....
, in south western Germany, known as the Upper Rhine valley
The Taupo Volcanic Zone
Taupo Volcanic Zone

The Taupo Volcanic Zone is a highly active volcano area in the North Island of New Zealand. It is named after Lake Taupo, the flooded caldera of the largest volcano in the zone....
in the north east North Island
North Island

The North Island is one of the two main islands of New Zealand, the other being the South Island. The island is 113,729 square km in area, making it the List of islands by area....
of New Zealand
New Zealand

New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses , and numerous Islands of New Zealand, most notably Stewart Island/Rakiura and the Chatham Islands....
The Oslo Graben
Oslo Graben

The Oslo Graben or Oslo Rift is a graben formed during a geologic Rift event in Permian time. The rift formation was accompanied by volcanic activity and associated rhomb porphyry lava flows....
in Norway
Norway

Norway , officially the Kingdom of Norway, is a constitutional monarchy in Northern Europe that occupies the western portion of the Scandinavian Peninsula....
The Ottawa-Bonnechere Graben
Ottawa-Bonnechere Graben

The Ottawa-Bonnechere Graben with its branch the Timiskaming Graben, is an ancient rift valley in the Canadian Shield of Northeastern Ontario and Quebec, Canada....
in Ontario and Quebec
The Northern Cordilleran Volcanic Province
Northern Cordilleran volcanic province

The Northern Cordilleran Volcanic Province , sometimes called the Stikine Volcanic Belt, is a group of volcanoes and volcanic fields located in the Pacific Northwest of North America....
in British Columbia
British Columbia

British Columbia is the westernmost of Canada's Provinces and territories of Canada and is famed for its natural beauty, as reflected in its Latin motto, Splendor sine occasu ....
, Yukon
Yukon

Yukon is the westernmost and smallest of Canada three Territories of Canada. It was named after the Yukon River, Yukon meaning "Great River" in Gwich?in language....
and Alaska
Alaska

Alaska is the largest U.S. state of the United States by area; it is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait....
The West Antarctic Rift
West Antarctic Rift

The West Antarctic Rift is a major, active rift lying between East Antarctica and West Antarctica. It encompasses the Ross Sea, the area under the Ross Ice Shelf and a part of West Antarctica....
in Antarctica
Antarctica

Antarctica is Earth's southernmost continent, overlying the South Pole. It is situated in the Antarctica of the southern hemisphere, almost entirely south of the Antarctic Circle, and is surrounded by the Southern Ocean....
The Midcontinent Rift System
Midcontinent Rift System

The Midcontinent Rift System or Keweenawan Rift is a long geological rift in the center of the North America and south-central part of the North American plate....
, a late Precambrian
Precambrian

The Precambrian is an informal name for the supereon comprising the eon of the geologic timescale that came before the current Phanerozoic eon....
rift in central North America
The Fundy Basin
Fundy Basin

The Fundy Basin is a sediment-filled rift on the Atlantic Ocean coast of southeastern Canada. It contains three sub-basins; the Fundy sub-basin, the Minas Basin and the Chignecto Basin....
, a Triassic
Triassic

The Triassic is a geologic period that extends from about 251 to 199 annum . As the first period of the Mesozoic Era, the Triassic follows the Permian and is followed by the Jurassic....
rift basin in southeastern Canada