A Submarine canyon is a steep-sided valley on the seafloor of the continental slope. Submarine canyons are generally found as extensions to large rivers, and have been found to extend 1km below sea level, and extend for hundreds of kilometers.

Characteristics

Submarine canyons are more common on steep slopes than on gentle slopes. They show erosion through all substrates, from unlithified sediment to crystalline rock. They are more densely spaced on steep slopes while being rare on gentle slopes. The walls are generally very steep or vertical. The walls are subject to erosion by turbidity currents, bioerosion, or slumping. A turbidity current or density current is a current of of rapidly moving, sediment-laden water moving down a slope through air, water, or another fluid. ... Bioerosion describes the erosion of hard ocean substrates by living organisms by a number of mechanisms. ...

Examples of submarine canyons

• Congo canyon, the largest river canyon, extending from the Congo river, is 800 km (500 miles) long, and 1,200m (4000 ft) deep.
• Amazon canyon, extending from the Amazon river
• Hudson canyon[1], extending from the Hudson river
• Ganges canyon, extending from the Ganges river
• Indus canyon, extending from the Indus river
• Monterey bay canyon, off the coast of central California
• La Jolla and Scripps canyon, off the coast of southern California
• Bering canyon, in the Bering sea

Image of Kinshasa and Brazzaville, taken by NASA; the Congo River is visible in the center of the photograph Length 4,380 km Elevation of the source  m Average discharge 41,800 m³/s Area watershed 3,680,000 km² Origin   Mouth  Atlantic Ocean Basin countries Dem. ... Length 6,296 km Elevation of the source 5,597 m Average discharge 219,000 m³/s Area watershed 6,915,000 km² Origin  Nevado Mismi Mouth  Atlantic Ocean Basin countries Brazil (62. ... View of the Hudson in the 1880s showing Jersey City The Hudson River, called Muh-he-kun-ne-tuk in Mahican, is a river running mainly through New York State but partly forming the boundary between the states of New York and New Jersey. ... Early morning on the Ganges The River Ganges hu (Ganga in Indian languages) (Devanagiri गंगा) is a major river in northern India. ... The Indus (Daria-e-Sindh, सिन्‍धु नदी) (known as Sindhu to Indians and in Sanskrit, as Sinthos in Greek, and Sindus in Latin) is the principal river of Pakistan. ... State nickname: The Golden State Other U.S. States Capital Sacramento Largest city Los Angeles Governor Arnold Schwarzenegger (R) Official languages English Area 410,000 km² (3rd)  - Land 404,298 km²  - Water 20,047 km² (4. ... State nickname: The Golden State Other U.S. States Capital Sacramento Largest city Los Angeles Governor Arnold Schwarzenegger (R) Official languages English Area 410,000 km² (3rd)  - Land 404,298 km²  - Water 20,047 km² (4. ...

Formation of submarine canyons

Two mechanisms have been suggested for the formation of submarine canyons, which may have worked in concert:

• Canyons may have been carved during a time when sea level was lower than present and rivers were able to flow out to the edge of the shelf. This theory is supported by the fact that many (but not all) canyons are found offshore from major rivers. A difficulty with this theory is that the sea level would have had to have been 3000m lower to account for the canyons.
• Canyons may have been carved by turbidity currents, or dense, sediment-laden currents triggered by earthquake which flow down the continental margin.

Global earthquake epicenters, 1963–1998 An earthquake is a trembling or a shaking movement of the Earths surface. ...

External links

• Modern deep-water canyons