The Northwest Atlantic Mid-Ocean Channel (NAMOC) is the main body of a

turbidity current 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. T ...

system of channels and canyons running on the sea bottom from the

Hudson Strait Hudson Strait (french: Détroit d'Hudson) links the Atlantic Ocean and Labrador Sea to Hudson Bay in Canada. This strait lies between Baffin Island and Nunavik, with its eastern entrance marked by Cape Chidley in Newfoundland and Labrador ...

, through the

Labrador Sea The Labrador Sea (French: ''mer du Labrador'', Danish: ''Labradorhavet'') is an arm of the North Atlantic Ocean between the Labrador Peninsula and Greenland. The sea is flanked by continental shelves to the southwest, northwest, and northeast. It ...

and ending at the Sohm Abyssal Plain in the

Atlantic Ocean The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe ...

. Contrary to most other such systems which fan away from the main channel, numerous

tributaries A tributary, or affluent, is a stream or river that flows into a larger stream or main stem (or parent) river or a lake. A tributary does not flow directly into a sea or ocean. Tributaries and the main stem river drain the surrounding drainag ...

run into the NAMOC and end there. The density of those tributaries is the highest near the

Labrador Peninsula The Labrador Peninsula, or Quebec-Labrador Peninsula, is a large peninsula in eastern Canada. It is bounded by the Hudson Bay to the west, the Hudson Strait to the north, the Labrador Sea to the east, and the Gulf of Saint Lawrence to the sout ...

, but the longest tributary, called Imarssuak Mid-Ocean Channel (IMOC), originates in the Atlantic Ocean. Most topography data on the NAMOC originate from wide-range

sonar Sonar (sound navigation and ranging or sonic navigation and ranging) is a technique that uses sound propagation (usually underwater, as in submarine navigation) to navigate, measure distances (ranging), communicate with or detect objects on o ...

scans. With a total length of about , NAMOC is one of the longest underwater channels in the world. It is 100–200 m deep and 2–5 km wide at the channel floor. The rising levees of the NAMOC (about 100 m above the sea bed) often hinder confluence of some tributaries, which instead run along NAMOC for hundreds of km. Its western (right-hand, max. height 250 m) levee rises some 100 m above the eastern one (max. height 150 m). This asymmetry is attributed to the

Coriolis effect In physics, the Coriolis force is an inertial or fictitious force that acts on objects in motion within a frame of reference that rotates with respect to an inertial frame. In a reference frame with clockwise rotation, the force acts to the ...

affecting the turbidity currents, which reach velocities of 6–8.5 m/s and deposit silt and clay over the channel. The levee is absent in some parts of the NAMOC, for example between 56°N and 57°N, due to the local side-flows of sand. The meandering of the NAMOC is relatively small compared to other underwater channels, such as Amazon Canyon. It is more developed in the northern part with a period increasing from 25 km between 59°45'N and 56°N to 50 km between 56°N and 54°30'N. The channel becomes on average more straight towards the south, but it still contains abrupt turns due to local seamounts sea bed fractures.

References

{{reflist, 2 Physical oceanography Labrador Sea Oceanography

See also

References