Submarine canyon

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Submarine canyon

A submarine canyon is a steep-sided valley

Valley

In geology, a valley is a Depression with predominant extent in one direction. A very deep river valley may be called a canyon or gorge....
on the sea floor of the continental slope. Many submarine canyon

Canyon

A canyon, or gorge, is a deep valley between cliffs often carved from the landscape by a river. Most canyons were formed by a process of long-time erosion from a plateau level....
s are found as extensions to large river

River

A river is a natural stream of water, usually freshwater, flowing toward an ocean, a lake, or another stream. In some cases a river flows into the ground or dries up completely before reaching another body of water....
s; however there are many that have no such association. Canyons cutting the continental slopes have been found at depths greater than 2 km

KM, Km, or km may stand for:*Kilometre *KM - the Michaelis constant in Michaelis-Menten kinetics*Kernel methods*Kettle Moraine High School...
below sea level

Sea level

Mean sea level is the average height of the sea, with reference to a suitable reference surface. Defining the reference level , however, involves complex measurement, and accurately determining MSL can prove difficult....
. They are formed by powerful turbidity current

Turbidity current

A turbidity current or density current is a current of rapidly moving, sediment-laden water moving down a slope through air, water, or another fluid....
s, volcanic

Volcano

A volcano is an opening, or rupture, in a planet's surface or Crust , which allows hot, molten rock, ash, and gases to escape from below the surface....
and earthquake

Earthquake

An earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. Earthquakes are recorded with a seismometer, also known as a seismograph....
activity. Many submarine canyons continue as submarine channels across continental rise areas and may extend for hundreds of kilometers.

arine canyons are more common on steep slopes than on gentle slopes.

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Encyclopedia

A submarine canyon is a steep-sided valley

Valley

Canyon

River

KM, Km, or km may stand for:*Kilometre *KM - the Michaelis constant in Michaelis-Menten kinetics*Kernel methods*Kettle Moraine High School...
below sea level

Sea level

Turbidity current

A turbidity current or density current is a current of rapidly moving, sediment-laden water moving down a slope through air, water, or another fluid....
s, volcanic

Volcano

A volcano is an opening, or rupture, in a planet's surface or Crust , which allows hot, molten rock, ash, and gases to escape from below the surface....
and earthquake

Earthquake

Characteristics

Submarine canyons are more common on steep slopes than on gentle slopes. They show erosion

Erosion

For morphological image processing operations, see Erosion 'For use of in dermatopathology, see Erosion Erosion is the removal of solids in the natural environment....
through all substrates, from unlithified

Lithification

Lithification is the process in which sediments compact under pressure, expel connate fluids, and gradually become solid rock. Essentially, lithification is a process of porosity destruction through Compaction and cementation ....
sediment

Sediment

Sediment is any particulate matter that can be sediment transport by fluid dynamics, and which eventually is deposited.Sediments are most often transported by water transported by wind and glaciers....
to crystalline rock

Rock (geology)

In geology, rock is a naturally occurring solid aggregate of minerals and/or mineraloids.The Earth's outer solid layer, the lithosphere, is made of rock....
. They are more densely spaced on steep slopes while being rare on gentle slopes. The walls are generally very steep and can be near vertical. The walls are subject to erosion by turbidity currents, bioerosion

Bioerosion

Bioerosion describes the erosion of hard Substrate s – and less often terrestrial substrates – by living organisms by a number of mechanisms....
, or slumping.

Examples

Congo canyon, the largest river canyon, extending from the Congo river
Congo River

The Congo River is the largest river in Western Central Africa. Its overall length of 4,700 km makes it the second longest in Africa ....
, is 800 km (500 mile
Mile

A mile is a Units of measurement of length, usually used to measure distance, in a number of different systems. In contemporary English contexts, mile most commonly refers to the statute mile of 5,280 Feet or the nautical mile of 1,852 meters ....
s) long, and 1200 metre
Metre

The metre or meter is a Unit of measurement of length. It is the SI base unit of length in the metric system and in the International System of Units , used around the world for general and scientific purposes....
s (3900 ft
Ft

selfref|On Wikipedia, Ft may refer to...
) deep.
Amazon canyon, extending from the Amazon river
Amazon River

The Amazon River of South America is the list of rivers by length in the world by volume, with a total river flow greater than the next top eight largest rivers combined....
Hudson Canyon
Hudson Canyon

The Hudson Canyon is a submarine canyon that begins from the shallow outlet of New York Harbor and extends out over 400 nautical miles seaward across the continental shelf, finally connecting to the deep ocean basin at a depth of 3 to 4 km below sea level....
, extending from the Hudson river
Hudson River

The Hudson River, called Muh-he-kun-ne-tuk , the Great Mohegan by the Iroquois, or as the Lenape Native Americans called it in Unami, Muhheakantuck, is a river that flows from north to south through eastern New York....
Ganges canyon, extending from the Ganges river
Ganges River

The 'Ganges' is one of the major rivers of the Indian subcontinent, flowing east through the Gangetic Plain of northern India into Bangladesh....
Indus canyon, extending from the Indus river
Indus River

File:Indian subcontinent CIA.pngThe Indus River is the longest river in Pakistan and the twenty-first largest river in the world, in terms of annual flow, on the Indian Subcontinent....
Monterey Canyon
Monterey Canyon

Monterey Canyon, or Monterey Submarine Canyon, is a submarine canyon in Monterey Bay, California. It is the subject of ongoing study by the scientists at the Monterey Bay Aquarium Research Institute,the Moss Landing Marine Laboratories, and other oceanography institutions....
, off the coast of central California
California

California is a U.S. state on the West Coast of the United States of the United States, along the Pacific Ocean. It is bordered by Oregon to the north, Nevada to the east, Arizona to the southeast, and to the south the Mexico state of Baja California....
La Jolla and Scripps canyon
Scripps Canyon

Scripps Canyon is a narrow underwater gorge located in the Pacific Ocean off the coast of southern California, USA. The canyon is approximately one mile long, which joins to La Jolla Canyon offshore....
, off the coast of La Jolla, southern California
Southern California

Southern California, or So Cal, is defined as the southern portion of the U.S. state of California. Its population centers on the cities of Los Angeles, California, San Diego, California, San Bernardino, California, and Riverside, California....
Whittard Canyon, Atlantic Ocean
Atlantic Ocean

The Atlantic Ocean is the second-largest of the world's oceanic divisions; with a total area of about 106.4 million square kilometres . It covers approximately one-fifth of the Earth's surface....
off southwest Ireland
Ireland

Ireland is the List of islands by area in Europe, and the twentieth-largest island in the world. It lies to the north-west of continental Europe and is surrounded by hundreds of islands and islet....
Bering Canyon
Bering Canyon

The Bering Canyon is the longest of the Bering Sea canyons; it extends about 400 km across the Bering shelf and slope. It is confined at its eastern edge by the Aleutian Islands....
, in the Bering sea
Bering Sea

The Bering Sea is a body of water in the Pacific Ocean that comprises a deep water basin, which then rises through a narrow slope into the shallower water above the continental shelf....
Zhemchug Canyon
Zhemchug Canyon

Zhemchug Canyon is a giant underwater canyon located in the middle of the Bering Sea. This submarine canyon is the largest canyon in the ocean....
the largest submarine canyon in the world, also in the Bering sea

Formation

Many mechanisms have been proposed for the formation of submarine canyons, and during the 1940s and 1950s the primary causes of submarine canyons were subject to active debate.

An early and obvious theory was that the canyons present today were carved during glacial times, when sea level was about 125 meters below present sea level, and rivers flowed to the edge of the continental shelf. However, while many (but not all) canyons are found offshore from major rivers, subaerial river erosion cannot have been active to the water depths as great as 3000 meters where canyons have been mapped, as it is well established (by many lines of evidence) that sea levels did not fall to those depths.

The major mechanism of canyon erosion is now thought to be turbidity currents and underwater landslide

Landslide

File:Guatemala landslide.jpgA landslide is a List of geological phenomena which includes a wide range of ground movement, such as rock falls, deep failure of slopes and shallow debris flows, which can occur in offshore, coastal and onshore environments....
s. Turbidity currents are dense

Density

The density of a material is defined as its mass per unit volume. The symbol of density is ....
, sediment-laden current

Current (fluid)

File:Water patterns.JPGA current, in a river or stream, is the flow of water influenced by gravity as the water moves downhill to reduce its potential energy....
s which flow downslope when an unstable mass of sediment that has been rapidly deposited on the upper slope fails, perhaps triggered by earthquakes. There is a spectrum of turbidity- or density-current types ranging from "mud

MUD

In Online game, a MUD , pronounced /m?d/, is a multi-user real-time virtual world described entirely in text. It combines elements of role-playing games, hack and slash, interactive fiction, and online chat....
dy water" to massive mudflow, and evidence of both these end members can be observed in deposits associated with the deeper parts of submarine canyons and channels, such as lobate deposits (mudflow) and levee

Levee

A levee, lev?e, dike , embankment, floodbank or stopbank is a natural or artificial slope or wall to regulate water levels....
s along channels.

Mass wasting

Mass wasting

Mass wasting, also known as slope movement or mass movement, is the geomorphology process by which soil, regolith, and rock move downslope under the force of gravity....
, slumping, and submarine landslides are forms of slope failures (the effect of gravity on a hillslope) observed in submarine canyons. Mass wasting is the term used for the slower and smaller action of material moving downhill; and would commonly include the effects of bioerosion: the burrowing, ingestion

Ingestion

Ingestion is the consumption of a substance by an organism. In animals, it normally is accomplished by taking in the substance through the mouth into the gastrointestinal tract, such as through eating or drinking....
and defecation

Defecation

Defecation is the final act of digestion by which organisms eliminate solid, semisolid or liquid waste material from the digestive tract via the anus....
of sediment performed by organism

Organism

In biology, an organism is any life thing . In at least some form, all organisms are capable of response to stimulus , reproduction, growth and developmental biology, and maintenance of homeostasis as a stable whole....
s. Slumping is generally used for rotational movement of masses on a hillside. Landslides, or slides, generally comprise the detachment and displacement of sediment masses. All are observed; all are contributory processes.

It is now understood that many mechanisms of submarine canyon creation have had effect to greater or lesser degree in different places, even within the same canyon, or at different times during a canyon's development. However, if a primary mechanism must be selected, the downslope lineal morphology

Geomorphology

Geomorphology is the scientific study of landforms and the processes that shape them. Geomorphologists seek to understand why landscapes look the way they do: to understand landform history and dynamics, and predict future changes through a combination of field observation, physical experiment, and numerical mathematical model....
of canyons and channels and the transportation of excavated or loose materials of the continental slope over extensive distances require that various kinds of turbidity or density currents act as major participants.

Submarine canyon

Characteristics

Examples

Formation

See also

External links