Misplaced Pages

#377622

35-595: The sea formed upon separation of the North American Plate and Greenland Plate that started about 60 million years ago and stopped about 40 million years ago. It contains one of the world's largest turbidity current channel systems, the Northwest Atlantic Mid-Ocean Channel (NAMOC), that runs for thousands of kilometers along the sea bottom toward the Atlantic Ocean. The Labrador Sea is

70-557: A craton . Along most of the edges of this craton are fragments of crustal material called terranes , which are accreted to the craton by tectonic actions over a long span of time. Much of North America west of the Rocky Mountains is composed of such terranes. The southern boundary with the Cocos plate to the west and the Caribbean plate to the east is a transform fault , represented by

105-408: A breeding ground for several types of pinnipeds (including Atlantic walrus and bearded , grey , harbor , harp , hooded and ringed seals ). Several cetacean species feed in these abundant waters in early spring, including blue , fin , humpback , long-finned pilot , minke , North Atlantic right , sei and sperm whales . The sea contains one of the two primary populations of sei whales,

140-615: A line joining this ledge with the East extreme of Cape St. Charles (52°13'N) in Labrador. Natural Resources Canada uses a slightly different definition, putting the northern boundary of the Labrador Sea on a straight line from a headland on Killiniq Island abutting Lady Job Harbour to Cape Farewell. The Labrador Sea is about 3,400 m (1,859 fathoms ; 11,155 feet ) deep and 1,000 km (621 miles ; 540 nautical miles ) wide where it joins

175-540: A major source of the North Atlantic Deep Water , a cold water mass that flows at great depth along the western edge of the North Atlantic. The Labrador Sea formed upon separation of the North American Plate and Greenland Plate that started about 60 million years ago ( Paleocene ) and stopped about 40 million years ago. A sedimentary basin , which is now buried under the continental shelves, formed during

210-509: A narrow stream of hot mantle convecting up from the Earth's core–mantle boundary called a mantle plume , although some geologists think that upper mantle convection is a more likely cause. The Yellowstone and Anahim hotspots are thought to have first arrived during the Miocene period and are still geologically active, creating earthquakes and volcanoes. The Yellowstone hotspot is most notable for

245-702: A part of the boundary. The rest of the southerly margin which extends east to the Mid-Atlantic Ridge and marks the boundary between the North American plate and the South American plate is vague but located near the Fifteen-Twenty fracture zone around 16°N. On the northerly boundary is a continuation of the Mid-Atlantic Ridge called the Gakkel Ridge . The rest of the boundary in the far northwestern part of

280-476: A relatively low vorticity, i.e. the tendency to form vortices, than any other water in North Atlantic that reflects its high homogeneity. It has a potential density of 27.76–27.78 mg/cm relatively to the surface layers, meaning it is denser, and thus sinks under the surface and remains homogeneous and unaffected by the surface fluctuations. The northern and western parts of the Labrador Sea are covered in ice between December and June. This drift ice serves as

315-535: Is relatively low, at 31–34.9 parts per thousand. Two-thirds of the sea is covered in ice in winter. Tides are semi-diurnal (i.e. occur twice a day), reaching 4 m (2.2 fathoms; 13 ft). There is an anticlockwise water circulation in the sea. It is initiated by the East Greenland Current and continued by the West Greenland Current , which brings warmer, more saline waters northwards, along

350-591: Is used to make herbal teas , are common in the area, both on the Greenland and Canadian coasts. North American Plate The North American plate is a tectonic plate containing most of North America , Cuba , the Bahamas , extreme northeastern Asia , and parts of Iceland and the Azores . With an area of 76 million km (29 million sq mi), it is the Earth's second largest tectonic plate, behind

385-672: The Atlantic Ocean and the 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 and Nunavut and Resolution Island , off Baffin Island . The strait is about 750 km (470 mi) long with an average width of 125 km (78 mi), varying from 70 km (43 mi) at

SECTION 10

#1732836934378

420-642: The Cretaceous . Onset of magmatic sea-floor spreading was accompanied by volcanic eruptions of picrites and basalts in the Paleocene at the Davis Strait and Baffin Bay. Between about 500 BC and 1300 AD, the southern coast of the sea contained Dorset , Beothuk , and Inuit settlements; Dorset tribes were later replaced by Thule people . Download coordinates as: The International Hydrographic Organization defines

455-642: The Pacific plate (which borders the plate to the west). It extends eastward to the seismically active Mid-Atlantic Ridge at the Azores triple junction plate boundary where it meets the Eurasian plate and Nubian plate . and westward to the Chersky Range in eastern Siberia. The plate includes both continental and oceanic crust . The interior of the main continental landmass includes an extensive granitic core called

490-803: The Swan Islands Transform Fault under the Caribbean Sea and the Motagua Fault through Guatemala . The parallel Septentrional and Enriquillo–Plantain Garden faults running through Hispaniola and bounding the Gonâve microplate , and the parallel Puerto Rico Trench running north of Puerto Rico and the Virgin Islands and bounding the Puerto Rico–Virgin Islands microplate , are also

525-739: The Yellowstone Caldera and the many calderas that lie in the Snake River Plain , while the Anahim hotspot is most notable for the Anahim Volcanic Belt in the Nazko Cone area. For the most part, the North American plate moves in roughly a southwest direction away from the Mid-Atlantic Ridge at a rate of about 2.3 centimeters (~1 inch) per year. At the same time, the Pacific plate is moving to

560-474: The cod fishing had already depleted the fishes' population near the Labrador and West Greenland banks, and was therefore halted in 1992. Other fishery targets include haddock , Atlantic herring , lobster , several species of flatfish , and pelagic fish , such as sand lance and capelin . They are most abundant in the southern parts of the sea. The Labrador duck was a common bird on the Canadian coast until

595-744: The 19th century, but is now extinct. Other coastal animals include the Labrador wolf ( Canis lupus labradorius ), woodland caribou ( Rangifer tarandus caribou ), moose ( Alces alces ), black bear ( Ursus americanus ), Canada lynx ( Lynx canadensis ), red fox ( Vulpes vulpes ), Arctic fox ( Alopex lagopus ), wolverine ( G. gulo ), American mink ( Neogale vison ), North American river otter ( Lontra canadensis ), snowshoe hare ( Lepus americanus ), grouse ( Dendragapus spp.), osprey ( Pandion haliaetus ), raven ( Corvus corax ), ducks , geese , swans , partridge and pheasant . Occasionally, coastal polar bear ( Ursus maritimus ) sightings occur along

630-436: The Atlantic Ocean. It becomes shallower, to less than 700 m (383 fathoms; 2,297 ft) towards Baffin Bay (see depth map ) and passes into the 300 km (190 mi; 160 nmi) wide Davis Strait . A 100–200 m (55–109 fathoms; 330–660 ft) deep turbidity current channel system, which is about 2–5 km (1.2–3.1 mi; 1.1–2.7 nmi) wide and 3,800 km (2,400 mi; 2,100 nmi) long, runs on

665-458: The Baffin Current is somewhat slower at about 0.2 m/s (0.66 ft/s). The Labrador Current maintains the water temperature at 0 °C (32 °F) and salinity between 30 and 34 parts per thousand. The sea provides a significant part of the North Atlantic Deep Water (NADW) — a cold water mass that flows at great depth along the western edge of the North Atlantic, spreading out to form

700-565: The Greenland coasts up to the Baffin Bay. Then, the Baffin Island Current and Labrador Current transport cold and less saline water southward along the Canadian coast. These currents carry numerous icebergs and therefore hinder navigation and exploration of the gas fields beneath the sea bed. The speed of the Labrador current is typically 0.3–0.5 m/s (0.98–1.64 ft/s), but can reach 1 m/s (3.3 ft/s) in some areas, whereas

735-602: The Northeast limit of the Gulf of St. Lawrence – a line running from Cape Bauld (North point of Kirpon Island , 51°40′N 55°25′W  /  51.667°N 55.417°W  / 51.667; -55.417  ( Cape Bauld ) ) to the East extreme of Belle Isle and on to the Northeast Ledge ( 52°02′N 55°15′W  /  52.033°N 55.250°W  / 52.033; -55.250  ( Belle Isle ) ). Thence

SECTION 20

#1732836934378

770-596: The bottom of the sea, near its center from the Hudson Strait into the Atlantic. It is called the Northwest Atlantic Mid-Ocean Channel (NAMOC) and is one of the world's longest drainage systems of Pleistocene age. It appears as a submarine river bed with numerous tributaries and is maintained by high-density turbidity currents flowing within the levees . The water temperature varies between −1 °C (30 °F) in winter and 5–6 °C (41–43 °F) in summer. The salinity

805-731: The coast of Alaska and the Cascadia subduction zone to the north, the San Andreas Fault through California , the East Pacific Rise in the Gulf of California , and the Middle America Trench to the south. On its western edge, the Farallon plate has been subducting under the North American plate since the Jurassic period. The Farallon plate has almost completely subducted beneath

840-639: The eastern entrance to 240 km (150 mi) at Deception Bay. English navigator Sir Martin Frobisher was the first European to report entering the strait, in 1578. He named a tidal rip at the entrance the Furious Overfall and called the strait Mistaken Strait , since he felt it held less promise as an entrance to the Northwest Passage than the body of water that was later named Frobisher Bay . Later in his 1587 voyage, explorer John Davis sailed by

875-508: The entrance to the strait. The first European to explore the strait was George Weymouth who sailed 300 nautical miles (560 km; 350 mi) beyond the Furious Overfall in 1602. The strait was named after Henry Hudson who explored it in 1610 in the ship Discovery , the same ship previously used by George Weymouth in 1602. Hudson was followed by Thomas Button in 1612, and a more detailed mapping expedition led by Robert Bylot and William Baffin in 1616. The Hudson Strait links

910-553: The largest identifiable water mass in the World Ocean . The NADW consists of three parts of different origin and salinity, and the top one, the Labrador Sea Water (LSW), is formed in the Labrador Sea. This part occurs at a medium depth and has a relatively low salinity (34.84–34.89 parts per thousand), low temperature (3.3–3.4 °C (37.9–38.1 °F)) and high oxygen content compared to the layers above and below it. LSW also has

945-689: The limits of the Labrador Sea as follows: On the North: the South limit of Davis Strait [The parallel of 60° North between Greenland and Labrador ]. On the East: a line from Cape St. Francis 47°45′N 52°27′W  /  47.750°N 52.450°W  / 47.750; -52.450  ( Cape St. Francis ) ( Newfoundland ) to Cape Farewell (Greenland). On the West: the East Coast of Labrador and Newfoundland and

980-637: The northern end of the East Pacific Rise in the mouth of the gulf to the San Andreas Fault system in the vicinity of the Salton Trough rift/ Brawley seismic zone . It is generally accepted that a piece of the North American plate was broken off and transported north as the East Pacific Rise propagated northward, creating the Gulf of California. However, it is as yet unclear whether the oceanic crust between

1015-608: The northwest at a speed of between 7 and 11 centimeters (~3-4 inches) per year. The motion of the plate cannot be driven by subduction as no part of the North American plate is being subducted, except for a small section comprising part of the Puerto Rico Trench ; thus other mechanisms continue to be investigated. One study in 2007 suggests that a mantle convective current is propelling the plate. Hudson Strait Hudson Strait ( French : Détroit d'Hudson ) in Nunavut links

1050-640: The other being the Scotian Shelf . Pods of beluga (white) whales are more common further to the north, west and south (notably in Baffin Bay , where their population reaches around 20,000 animals), and further afield in Hudson Bay and the Gulf of Saint Lawrence . While somewhat rarer in the Labrador Sea—especially since the 1950s— some sightings still take place. Additionally, pods of orca are drawn to

1085-831: The plate extends into Siberia . This boundary continues from the end of the Gakkel Ridge as the Laptev Sea Rift , on to a transitional deformation zone in the Chersky Range , then the Ulakhan Fault between it and the Okhotsk microplate , and finally the Aleutian Trench to the end of the Queen Charlotte Fault system (see also: Aleutian Arc ). The westerly boundary is the Queen Charlotte Fault running offshore along

Labrador Sea - Misplaced Pages Continue

1120-488: The rise and the mainland coast of Mexico is actually a new plate beginning to converge with the North American plate, consistent with the standard model of rift zone spreading centers generally. A few hotspots are thought to exist below the North American plate. The most notable hotspots are the Yellowstone (Wyoming), Jemez Lineament (New Mexico), and Anahim (British Columbia) hotspots. These are thought to be caused by

1155-408: The sea by the large shoals of fish, as well as the many marine mammal species they may hunt (including other cetaceans and pinnipeds), such as harbour porpoise and Atlantic white-sided , common , striped and white-beaked dolphins . The sea is also a feeding-ground for Atlantic salmon . Shrimp fisheries began in 1978, intensifying by 2000, in addition to cod fishing. However, by the 1990s ,

1190-446: The sea, mainly further north but sometimes as far south as Conception Bay and the mouth of the Gulf of Saint Lawrence. Coastal vegetation includes black spruce ( Picea mariana ), tamarack , white spruce ( P. glauca ), dwarf birch ( Betula spp.), aspen , willow ( Salix spp.), ericaceous shrubs ( Ericaceae ), cottongrass ( Eriophorum spp.), sedge ( Carex spp.), lichens and moss. Evergreen bushes of Labrador tea , which

1225-494: The western portion of the North American plate, leaving that part of the North American plate in contact with the Pacific plate as the San Andreas Fault. The Juan de Fuca , Explorer , Gorda , Rivera , Cocos and Nazca plates are remnants of the Farallon plate. The boundary along the Gulf of California is complex. The gulf is underlain by the Gulf of California Rift Zone , a series of rift basins and transform fault segments from

#377622