A turbidite is the geologic deposit of a turbidity current, which is a type of amalgamation of fluidal and sediment gravity flow responsible for distributing vast amounts of clastic sediment into the deep ocean.
A submarine canyon is a steep-sided valley cut into the seabed of the continental slope, sometimes extending well onto the continental shelf, having nearly vertical walls, and occasionally having canyon wall heights of up to 5 km, from canyon floor to canyon rim, as with the Great Bahama Canyon. Just as above-sea-level canyons serve as channels for the flow of water across land, submarine canyons serve as channels for the flow of turbidity currents across the seafloor. Turbidity currents are flows of dense, sediment laden waters that are supplied by rivers, or generated on the seabed by storms, submarine landslides, earthquakes, and other soil disturbances. Turbidity currents travel down slope at great speed, eroding the continental slope and finally depositing sediment onto the abyssal plain, where the particles settle out.
A turbidity current is most typically an underwater current of usually rapidly moving, sediment-laden water moving down a slope; although current research (2018) indicates that water-saturated sediment may be the primary actor in the process. Turbidity currents can also occur in other fluids besides water.
Monterey Canyon, or Monterey Submarine Canyon, is a submarine canyon in Monterey Bay, California with steep canyon walls measuring a full 1 mile in height from bottom to top, which height/depth rivals the depth of the Grand Canyon itself. It is the largest such submarine canyon along the West coast of the North American continent, and was formed by the underwater erosion process known as turbidity current erosion. Many questions remain unresolved regarding the exact nature of its origins, and as such it is the subject of several ongoing geological and marine life studies being carried out by scientists stationed at the nearby Monterey Bay Aquarium Research Institute, the Moss Landing Marine Laboratories, and other oceanographic institutions.
The Bengal Fan, also known as the Ganges Fan, is the largest submarine fan on Earth.
The Hudson Canyon is a submarine canyon that begins from the shallow outlet of the estuary at the mouth of the Hudson River. It extends out over 640 km (400 mi) seaward across the continental shelf finally connecting to the deep ocean basin at a depth of 3 to 4 km below sea level. It begins as a natural channel of several kilometers width, starting as a 20–40 m depression at Hudson Channel southward from Ambrose Light, then carving through a deep notch of about 1 km depth in the shelf break, and running down the continental rise. Tidally associated flows of about 30 cm/s (1.1 km/h) up and down the deeper parts of the canyon have been recorded. As silt, sand and mud are carried down the Hudson River, they flow into the canyon and out into the deep sea.
A subaqueous fan is a fan-shaped deposit formed beneath water, and are commonly related to glaciers and crater lakes.
The continental rise is a low-relief zone of accumulated sediments that lies between the continental slope and the abyssal plain. It is a major part of the continental margin, covering around 10% of the ocean floor.
Abyssal channels are channels in Earth's sea floor. They are formed by fast-flowing floods of turbid water caused by avalanches near the channel's head, with the sediment carried by the water causing a build-up of the surrounding abyssal plains. Submarine channels and the turbidite systems which form them are responsible for the accumulation of most sandstone deposits found on continental slopes and have proven to be one of the most common types of hydrocarbon reservoirs found in these regions.
Submarine landslides are marine landslides that transport sediment across the continental shelf and into the deep ocean. A submarine landslide is initiated when the downwards driving stress exceeds the resisting stress of the seafloor slope material, causing movements along one or more concave to planar rupture surfaces. Submarine landslides take place in a variety of different settings, including planes as low as 1°, and can cause significant damage to both life and property. Recent advances have been made in understanding the nature and processes of submarine landslides through the use of sidescan sonar and other seafloor mapping technology.
A contourite is a sedimentary deposit commonly formed on continental rise to lower slope settings, although they may occur anywhere that is below storm wave base. Countourites are produced by thermohaline-induced deepwater bottom currents and may be influenced by wind or tidal forces. The geomorphology of contourite deposits is mainly influenced by the deepwater bottom-current velocity, sediment supply, and seafloor topography.
Hemipelagic sediment, or hemipelagite, is a type of marine sediment that consists of clay and silt-sized grains that are terrigenous and some biogenic material derived from the landmass nearest the deposits or from organisms living in the water. Hemipelagic sediments are deposited on continental shelves and continental rises, and differ from pelagic sediment compositionally. Pelagic sediment is composed of primarily biogenic material from organisms living in the water column or on the seafloor and contains little to no terrigenous material. Terrigenous material includes minerals from the lithosphere like feldspar or quartz. Volcanism on land, wind blown sediments as well as particulates discharged from rivers can contribute to Hemipelagic deposits. These deposits can be used to qualify climatic changes and identify changes in sediment provenances.
The Northwest Atlantic Mid-Ocean Channel (NAMOC) is the main body of a turbidity current system of channels and canyons running on the sea bottom from the Hudson Strait, through the Labrador Sea and ending at the Sohm Abyssal Plain in the Atlantic Ocean. Contrary to most other such systems which fan away from the main channel, numerous tributaries run into the NAMOC and end there. The density of those tributaries is the highest near the Labrador Peninsula, but the longest tributary, called Imarssuak Mid-Ocean Channel (IMOC), originates in the Atlantic Ocean.
A sediment gravity flow is one of several types of sediment transport mechanisms, of which most geologists recognize four principal processes. These flows are differentiated by their dominant sediment support mechanisms, which can be difficult to distinguish as flows can be in transition from one type to the next as they evolve downslope.
Congo Canyon is a submarine canyon found at the end of the Congo River in Africa. It is one of the largest submarine canyons in the world.
The Quinault Canyon is a submarine canyon, off Washington state, in Olympic Coast National Marine Sanctuary.
Cascadia Channel is the most extensive deep-sea channel currently known of the Pacific Ocean. It extends across Cascadia Abyssal Plain, through the Blanco Fracture Zone, and into Tufts Abyssal Plain. Notably, Cascadia Channel has tributaries, akin to river tributaries.
The Astoria Fan is a submarine fan. It has sediment, radiating asymmetrically southward from the mouth of the Astoria Canyon. From Astoria Canyon's mouth, the fan extends about 100 kilometres (62 mi) to its western end, which is the Cascadia Channel. The fan proper ends 160 kilometres (99 mi) south of the canyon mouth, although its depositional basin extends southward another 150 kilometres (93 mi) to the Blanco Fracture Zone.
Madeira Abyssal Plain, also called Madeira Plain, is an abyssal plain situated at the center and deepest part of the Canary Basin. It is a north-northeast to south-southeast elongated basin that almost parallels the Mid-Atlantic Ridge. Its western boundary is marked by a chain of seamounts known as the either Seewarte Seamounts or Atlantis-Great Meteor Seamount Chain. Its eastern boundary is a distinct break of slope that marks the foot of the African Continental Rise. This abyssal plain occupies an area of about 68,000 km2 (26,000 sq mi). Across this basin, slope angles are generally less than 0.01°.
The Kaikōura Canyon is a geologically active submarine canyon located southwest of the Kaikōura Peninsula off the northeastern coast of the South Island of New Zealand. It is 60 kilometres (37 mi) long, and is generally U-shaped. The canyon descends into deep water and merges into an ocean channel system that can be traced for hundreds of kilometres across the deep ocean floor. At the head of the Kaikōura Canyon, the depth of water is around 30 metres (98 ft), but it drops rapidly to 600 metres (2,000 ft) and continues down to around 2,000 metres (6,600 ft) deep where it meets the Hikurangi Channel. Sperm whales can be seen close to the coast south of Goose Bay, because the deep water of the Kaikōura Canyon is only one kilometre (0.62 mi) off the shoreline in this area.
