Submarine canyons are steep-sided ocean valleys situated along the floor of the continental slope. Submarine canyons are believed to be extensions of continental faults or rivers. Other theories try to relate the formation of submarine canyons to the Pleistocene era when submarine canyons may have been submerged under the ocean water. Another theory states that they may have been carved by sediment transport and erosion of their overlying layers originated by water turbidity and landslides probably triggered by earthquakes, storms and ocean currents.
Submarine canyons are usually situated cutting along the regions of a continental slope. They’re more densely spaced on the steep slopes, while being uncommon on the gentler slopes. The walls of submarine canyons are usually very steep, and in some parts of the canyon, they can be virtually vertical. The walls of a submarine canyon are subject to erosion and slumping caused by earth movements, shocks, freezing and thawing. The causes of submarine canyon formation were a subject under active debate in the mid twentieth century, and many theories were discussed at that time.
Pleistocene origin
An early theory was that submarine canyons were carved during the glacial period when the sea levels drop temporarily by up to 100 meters (300 ft.) on the entire surface of the Earth. During this times, rivers might have flowed to the edge of the continental shelf; however, this theory leaves open the considerations of other theories, since while many submarine canyons, although not all, are found to coincide with major rivers, subaerial erosion could not have been occurred to depths over 300 meters (900 ft.), where submarine canyons have been charted.
Subaerial erosion
This theory states that submarine canyons have tributary systems similar to rivers cutting through valleys on the surface of the Earth. The canyons seem to slope outward along their courses and lack basin depressions. Most submarine canyons appear to be related to drainage systems, such as rivers, on land. Submarines canyons are too large to be explained by excavation of river currents on land. Those submarine canyons that seem to have been cut by rivers and erosion might have required a very powerful source of forming agent.
Scientific concensus
Scientists now understand that a variety of forming mechanisms may have contributed to the formation of submarine canyons in a lesser or greater degree throughout different periods of time during the development of the canyon. The downslope physical feature of canyons and tributary channels require that several dynamic factors take place to produce erosion and sediment transport of their overlying layers. Various kinds of turbidity currents, tidal fluctuations, storms, earthquakes and landslides are believed to contribute to the formation of submarine canyons.
Because submarine canyons occupy shallow water extensions, as well as deep ocean waters, they are inhabited by a great diversity of ocean life. Often, landslides from submarine canyon walls deposit rich-nutrient sediments on the ocean floor, which serve as food for deep-ocean organisms. Most organisms found in the depths of submarine canyons are not unique to them, but are also found in other deep-ocean habitats. The rocky protrusions along submarine canyon walls are inhabited by invertebrates, such as feather stars, corals and tunicates, and they also provide habitat for clams, worms and fish.
Submarine canyons are important ocean wild life and marine ecosystems. The Monterrey Canyon in Monterrey bay, California is the subject of ongoing research. The Monterrey canyon provides a perfect ground for scientific study due to its resemblance to deep ocean ecosystems. A series of explorations on deep-water canyons known as the Atlantic Canyons Undersea Mapping Expeditions (ACUMEN) are expected to occur between February and august 2012. The expeditions are intended to collect sufficient data to support scientific research.
