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116-791: Viscount Melville Sound , formerly Melville Sound, is an arm of the Arctic Ocean in the Kitikmeot Region , Nunavut and the Inuvik Region , Northwest Territories , Canada. Forming part of the Parry Channel , it separates Victoria Island and Prince of Wales Island from the Queen Elizabeth Islands . East of the sound , via Barrow Strait , lies Lancaster Sound , leading into Baffin Bay ; westward lies

232-884: A Native American source population related to the Ainu ancestors, the Jōmon . Paleo-Indian skeletons in the Americas such as Kennewick Man (Washington State), Hoya Negro skeleton (Yucatán), Luzia Woman and other skulls from the Lagoa Santa site (Brazil), Buhl Woman (Idaho), Peñon Woman III , two skulls from the Tlapacoya site (Mexico City), and 33 skulls from Baja California have exhibited certain craniofacial traits distinct from most modern Native Americans, leading physical anthropologists to posit an earlier "Paleoamerican" population wave. The most basic measured distinguishing trait

348-677: A branch of Ancient East Asians migrated to Northeastern Siberia, and mixed with descendants of the ANE, leading to the emergence of Ancient Paleo-Siberian and Native American populations in Extreme Northeastern Asia. However, the Beringian standstill hypothesis is not supported by paternal DNA evidence, which may reflect different population histories for paternal and maternal lineages in Native Americans, which

464-615: A daughter population of ancient East Asians, who they encountered around 25,000 years ago, which led to the emergence of Native American ancestral populations. However, the exact location where the admixture took place is unknown, and the migratory movements that united the two populations are a matter of debate. One theory supposes that Ancient North Eurasians migrated south to East Asia , or Southern Siberia , where they would have encountered and mixed with ancient East Asians. Genetic evidence from Lake Baikal in Russia supports this area as

580-751: A durable and extensive geographic feature connecting Siberia with Alaska. With the rise of sea level after the Last Glacial Maximum (LGM), the Beringian land bridge was again submerged. Estimates of the final re-submergence of the Beringian land bridge based purely on present bathymetry of the Bering Strait and eustatic sea level curve place the event around 11,000 years BP (Figure 1). Ongoing research reconstructing Beringian paleogeography during deglaciation could change that estimate and possible earlier submergence could further constrain models of human migration into North America. The onset of

696-482: A lineage found among Native Americans and Han Chinese, emerged around 20,000 BP, constraining the emergence of D4h3 to post-LGM. Age estimates based on Y-chromosome micro-satellite diversity place origin of the American Haplogroup Q1a3a (Y-DNA) at around 15,000 to 10,000 BP. Greater consistency of DNA molecular evolution rate models with each other and with archaeological data may be gained by

812-404: A lure for coastal migration. Reconstruction of the southern Beringian coastline also suggests potential for a highly productive coastal marine environment. Pollen data indicate a warm period culminating between 17,000 and 13,000 BP followed by cooling between 13,000 and 11,500 BP. Coastal areas deglaciated rapidly as coastal alpine glaciers, then lobes of Cordilleran ice, retreated. The retreat

928-505: A much earlier date, possibly 40,000 years ago, followed by a much later second wave of immigrants. The Clovis First theory, which dominated thinking on New World anthropology for much of the 20th century, was challenged in the 2000s by the secure dating of archaeological sites in the Americas to before 13,000 years ago. The archaeological sites in the Americas with the oldest dates that have gained broad acceptance are all compatible with an age of about 15,000 years. This includes

1044-747: A number of continental shelves , including the Canadian Arctic shelf, underlying the Canadian Arctic Archipelago , and the Russian continental shelf , which is sometimes called the "Arctic Shelf" because it is larger. The Russian continental shelf consists of three separate, smaller shelves: the Barents Shelf, Chukchi Sea Shelf and Siberian Shelf . Of these three, the Siberian Shelf is the largest such shelf in

1160-486: A warming of approximately 5–8 °C (9–14 °F), the region reached an average annual temperature of 10–20 °C (50–68 °F). The surface waters of the northernmost Arctic Ocean warmed, seasonally at least, enough to support tropical lifeforms (the dinoflagellates Apectodinium augustum ) requiring surface temperatures of over 22 °C (72 °F). Settlement of the Americas While there

1276-716: Is Molloy Hole in the Fram Strait , at about 5,550 m (18,210 ft). The two major basins are further subdivided by ridges into the Canada Basin (between Beaufort Shelf of North America and the Alpha Ridge ), Makarov Basin (between the Alpha and Lomonosov Ridges), Amundsen Basin (between Lomonosov and Gakkel ridges), and Nansen Basin (between the Gakkel Ridge and the continental shelf that includes

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1392-464: Is a stub . You can help Misplaced Pages by expanding it . Arctic Ocean Main five oceans division: Further subdivision: The Arctic Ocean is the smallest and shallowest of the world's five oceanic divisions . It spans an area of approximately 14,060,000 km (5,430,000 sq mi) and is the coldest of the world's oceans. The International Hydrographic Organization (IHO) recognizes it as an ocean, although some oceanographers call it

1508-506: Is a long-standing open question. While advances in archaeology , Pleistocene geology , physical anthropology , and DNA analysis have progressively shed more light on the subject, significant questions remain unresolved. The " Clovis first theory" refers to the hypothesis that the Clovis culture represents the earliest human presence in the Americas about 13,000 years ago. Evidence of pre-Clovis cultures has accumulated and pushed back

1624-414: Is a section referred to as the sub-surface layer. It is a product of Atlantic water that enters through canyons and is subjected to intense mixing on the Siberian Shelf. As it is entrained, it cools and acts a heat shield for the surface layer on account of weak mixing between layers. However, over the past couple of decades a combination of the warming and the shoaling of Atlantic water are leading to

1740-477: Is cloudy year-round, with mean cloud cover ranging from 60% in winter to over 80% in summer. The temperature of the surface water of the Arctic Ocean is fairly constant at approximately −1.8 °C (28.8 °F), near the freezing point of seawater . The density of sea water, in contrast to fresh water, increases as it nears the freezing point and thus it tends to sink. It is generally necessary that

1856-565: Is contained in a polar climate characterized by persistent cold and relatively narrow annual temperature ranges. Winters are characterized by the polar night , extreme cold, frequent low-level temperature inversions, and stable weather conditions. Cyclones are only common on the Atlantic side. Summers are characterized by continuous daylight ( midnight sun ), and air temperatures can rise slightly above 0 °C (32 °F). Cyclones are more frequent in summer and may bring rain or snow. It

1972-551: Is general agreement that the Americas were first settled from Asia, the pattern of migration and the place(s) of origin in Eurasia of the peoples who migrated to the Americas remain unclear. The traditional theory is that Ancient Beringians moved when sea levels were significantly lowered due to the Quaternary glaciation , following herds of now-extinct Pleistocene megafauna along ice-free corridors that stretched between

2088-540: Is less than 100%. The HTLV virus genome has been mapped, allowing identification of four major strains and analysis of their antiquity through mutations. The highest geographic concentrations of the strain HLTV-1 are in sub-Saharan Africa and Japan. In Japan, it occurs in its highest concentration on Kyushu . It is also present among African descendants and native populations in the Caribbean region and South America. It

2204-627: Is not uncommon and has been observed in other populations. A 2019 study suggested that Native Americans are the closest living relatives to 10,000-year-old fossils found near the Kolyma River in northeastern Siberia. A study published in July 2022 suggested that people in southern China may have contributed to the Native American gene pool, based on the discovery and DNA analysis of 14,000-year-old human fossils. The contrast between

2320-511: Is now Western Canada , would have allowed migration before the beginning of the Holocene . However, a 2016 study has argued against this, suggesting that the peopling of North America via such a corridor is unlikely to significantly pre-date the earliest Clovis sites. The study concludes that the ice-free corridor in what is now Alberta and British Columbia "was gradually taken over by a boreal forest dominated by spruce and pine trees" and that

2436-664: Is one of the five mtDNA haplogroups found in Indigenous Americans. Native Americans mostly belong to the X2a clade, which has never been found in the Old World . According to Jennifer Raff , X2a probably originated in the same Siberian population as the other four founding maternal lineages, and that there is no compelling reason to believe it is related to X lineages found in Europe or West Eurasia. The Kennewick man fossil

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2552-677: Is predominantly cyclonic on the Eurasian side and anticyclonic in the Canadian Basin . Water enters from both the Pacific and Atlantic Oceans and can be divided into three unique water masses. The deepest water mass is called Arctic Bottom Water and begins around 900 m (3,000 ft) depth. It is composed of the densest water in the World Ocean and has two main sources: Arctic shelf water and Greenland Sea Deep Water. Water in

2668-809: Is rare in Central America and North America. Its distribution in the Americas has been regarded as due to importation with the slave trade. The Ainu have developed antibodies to HTLV-1, indicating its endemicity to the Ainu and its antiquity in Japan. A subtype "A" has been defined and identified among the Japanese (including Ainu ), and among Caribbean and South American isolates. A subtype "B" has been identified in Japan and India. In 1995, Native Americans in coastal British Columbia were found to have both subtypes A and B. Bone marrow specimens from an Andean mummy about 1500 years old were reported to have shown

2784-537: Is the dolichocephaly of the skull. Some modern isolated populations such as the Pericúes of Baja California and the Fuegians of Tierra del Fuego exhibit that same morphological trait. Other anthropologists advocate an alternative hypothesis that evolution of an original Beringian phenotype gave rise to a distinct morphology that was similar in all known Paleoamerican skulls, followed by later convergence towards

2900-495: Is the highest volumetric inflow to the Arctic Ocean, equalling about 10 times that of the Pacific inflow, and it creates the Arctic Ocean Boundary Current. It flows slowly, at about 0.02 m/s. Atlantic Water has the same salinity as Arctic Bottom Water but is much warmer (up to 3 °C [37 °F]). In fact, this water mass is actually warmer than the surface water and remains submerged only due to

3016-499: The Alexander Archipelago . The now-submerged coastal plain has potential for more refugia. Pollen data indicate mostly herb/shrub tundra vegetation in unglaciated areas, with some boreal forest towards the southern end of the range of Cordilleran ice. The coastal marine environment remained productive, as indicated by fossils of pinnipeds . The highly productive kelp forests over rocky marine shallows may have been

3132-687: The Arctic Mediterranean Sea . It has also been described as an estuary of the Atlantic Ocean . It is also seen as the northernmost part of the all-encompassing world ocean . The Arctic Ocean includes the North Pole region in the middle of the Northern Hemisphere and extends south to about 60°N . The Arctic Ocean is surrounded by Eurasia and North America, and the borders follow topographic features:

3248-744: The Bering Strait on the Pacific side and the Greenland Scotland Ridge on the Atlantic side. It is mostly covered by sea ice throughout the year and almost completely in winter . The Arctic Ocean's surface temperature and salinity vary seasonally as the ice cover melts and freezes; its salinity is the lowest on average of the five major oceans, due to low evaporation , heavy fresh water inflow from rivers and streams, and limited connection and outflow to surrounding oceanic waters with higher salinities. The summer shrinking of

3364-811: The Buttermilk Creek Complex in Texas, the Meadowcroft Rockshelter site in Pennsylvania and the Monte Verde site in southern Chile. Archaeological evidence of pre- Clovis people points to the South Carolina Topper Site being 16,000 years old, at a time when the glacial maximum would have theoretically allowed for lower coastlines. It has often been suggested that an ice-free corridor, in what

3480-608: The Cretaceous period, the Canadian Basin opened, and tectonic activity due to the assembly of Alaska caused hydrocarbons to migrate toward what is now Prudhoe Bay. At the same time, sediments shed off the rising Canadian Rockies built out the large Mackenzie Delta. The rifting apart of the supercontinent Pangea , beginning in the Triassic period, opened the early Atlantic Ocean. Rifting then extended northward, opening

3596-614: The Eurasian Basin , which is 4,000–4,500 m (13,100–14,800 ft) deep, and the Amerasian Basin (sometimes called the North American or Hyperborean Basin), which is about 4,000 m (13,000 ft) deep. The bathymetry of the ocean bottom is marked by fault block ridges, abyssal plains , ocean deeps , and basins. The average depth of the Arctic Ocean is 1,038 m (3,406 ft). The deepest point

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3712-655: The Franz Josef Land ). The crystalline basement rocks of mountains around the Arctic Ocean were recrystallized or formed during the Ellesmerian orogeny, the regional phase of the larger Caledonian orogeny in the Paleozoic Era. Regional subsidence in the Jurassic and Triassic periods led to significant sediment deposition, creating many of the reservoirs for current day oil and gas deposits. During

3828-584: The Independence I and Independence II cultures of northeastern Canada and Greenland ( c.  2400–1800 BC and c.  800–1 BC ); and the Groswater of Labrador and Nunavik . The Dorset culture spread across Arctic North America between 500 BC and AD 1500. The Dorset were the last major Paleo-Eskimo culture in the Arctic before the migration east from present-day Alaska of

3944-461: The Laurentide and Cordilleran ice sheets. Another route proposed is that, either on foot or using boats , they migrated down the Pacific coast to South America as far as Chile . Any archaeological evidence of coastal occupation during the last Ice Age would now have been covered by the sea level rise , up to a hundred metres since then. The precise date for the peopling of the Americas

4060-554: The M'Clure Strait and the Arctic Ocean / Beaufort Sea . The sound is a part of the Northwest Passage . In 1854, Edward Belcher abandoned his ship, HMS Resolute , in the sound while searching for Sir John Franklin and his lost expedition . In 1855 HMS Resolute was found drifting off Baffin Island , and was later ceremonially returned to Queen Victoria . This Kitikmeot Region , Nunavut location article

4176-544: The North American extinction event that occurred at the end of the Pleistocene. Their genome , however, contains evidence of a bottleneck – something that can be used to test hypothesis on migrations between the two continents. Early human groups were largely nomadic , relying on following food sources for survival. Mobility was part of what made humans successful. As nomadic groups, early humans likely followed

4292-603: The Northwest Passage , to " Cathay " ( China ) caused water to win out, and by 1723 mapmakers such as Johann Homann featured an extensive "Oceanus Septentrionalis" at the northern edge of their charts. The few expeditions to penetrate much beyond the Arctic Circle in that era added only small islands, such as Novaya Zemlya (11th century) and Spitzbergen (1596), though, since these were often surrounded by pack-ice , their northern limits were not so clear. The makers of navigational charts , more conservative than some of

4408-564: The Puget lowlands up to 16,800 BP. Even during the maximum extent of coastal ice, unglaciated refugia persisted on present-day islands, that supported terrestrial and marine mammals. As deglaciation occurred, refugia expanded until the coast became ice-free by 15,000 BP. The retreat of glaciers on the Alaskan Peninsula provided access from Beringia to the Pacific coast by around 17,000 BP. The ice barrier between interior Alaska and

4524-625: The Sea of Okhotsk , shows a marked shift from tree and shrub pollen to herb pollen prior to 30,000 BP, as herb tundra replaced boreal forest and shrub steppe going into the LGM. A similar record of tree/shrub pollen being replaced with herb pollen as the LGM approached was recovered near the Kolyma River in Arctic Siberia. The abandonment of the northern regions of Siberia due to rapid cooling or

4640-580: The Thule people , ancestors of the modern Inuit . The Thule Tradition lasted from about 200 BC to AD 1600, arising around the Bering Strait and later encompassing almost the entire Arctic region of North America. The Thule people were the ancestors of the Inuit, who now live in Alaska, Northwest Territories , Nunavut , Nunavik (northern Quebec), Labrador and Greenland. For much of European history ,

4756-684: The Ulchis of the lower Amur River region (4 among 87 sampled, or 4.6%), along with Subhaplogroup C1a (1 among 87, or 1.1%). Subhaplogroup C1a is regarded as a close sister clade of the Native American Subhaplogroup C1b. Subhaplogroup D1a has also been found among ancient Jōmon skeletons from Hokkaido The modern Ainu are regarded as descendants of the Jōmon. The occurrence of the Subhaplogroups D1a and C1a in

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4872-653: The Wisconsin glaciation , the Earth's ocean water was, to varying degrees over time, stored in glacier ice. As water accumulated in glaciers, the volume of water in the oceans correspondingly decreased, resulting in lowering of global sea level . The variation of sea level over time has been reconstructed using oxygen isotope analysis of deep sea cores, the dating of marine terraces, and high-resolution oxygen isotope sampling from ocean basins and modern ice caps. A drop of eustatic sea level by about 60 to 120 metres (200 to 390 ft) from present-day levels, commencing around 30,000 years Before Present (BP), created Beringia ,

4988-440: The "Clovis people likely came from the south, not the north, perhaps following wild animals such as bison ". An alternative hypothesis for the peopling of America is coastal migration , which may have been feasible along the deglaciated (but now submerged) coastline of the Pacific Northwest from about 16,000 years ago. Pre-LGM migration across Beringia has been proposed to explain purported pre-LGM ages of archaeological sites in

5104-409: The Americas followed by isolation of the northern population following closure of the ice-free corridor. Evidence of Australo-Melanesians admixture in Amazonian populations was found by Skoglund and Reich (2016). A study of the diversification of mtDNA Haplogroups C and D from southern Siberia and eastern Asia, respectively, suggests that the parent lineage (Subhaplogroup D4h) of Subhaplogroup D4h3,

5220-408: The Americas occurring around 10,000 to 15,000 years after isolation of the small founding population . Another model (Kitchen et al. 2008) proposes that migration into Beringia occurred approximately 36,000 BP, followed by 20,000 years of isolation in Beringia. A third model (Nomatto et al. 2009) proposes that migration into Beringia occurred between 40,000 and 30,000 BP, with a pre-LGM migration into

5336-663: The Americas such as Bluefish Caves and Old Crow Flats in the Yukon Territory , and Meadowcroft Rock Shelter in Pennsylvania. The oldest archaeological sites on the Alaskan side of Beringia date to around 14,000 BP. It is possible that a small founder population had entered Beringia before that time. However, archaeological sites that date closer to the LGM on either the Siberian or the Alaskan side of Beringia are lacking. Biomarker and microfossil analyses of sediments from Lake E5 and Burial Lake in northern Alaska suggest human presence in eastern Beringia as early as 34,000 years ago. These sedimentary analyses have been suggested to be

5452-412: The Arctic Ocean as mafic oceanic crust material erupted out of a branch of Mid-Atlantic Ridge. The Amerasia Basin may have opened first, with the Chukchi Borderland moved along to the northeast by transform faults. Additional spreading helped to create the "triple-junction" of the Alpha-Mendeleev Ridge in the Late Cretaceous epoch . Throughout the Cenozoic Era, the subduction of the Pacific plate,

5568-427: The Arctic Ocean has a uniquely complex system of water flow. It resembles some hydrological features of the Mediterranean Sea , referring to its deep waters having only limited communication through the Fram Strait with the Atlantic Basin , "where the circulation is dominated by thermohaline forcing". The Arctic Ocean has a total volume of 18.07 × 10 km , equal to about 1.3% of the World Ocean. Mean surface circulation

5684-403: The Arctic Ocean. Much of the Arctic ice pack is also covered in snow for about 10 months of the year. The maximum snow cover is in March or April—about 20–50 cm (7.9–19.7 in) over the frozen ocean. The climate of the Arctic region has varied significantly during the Earth's history. During the Paleocene–Eocene Thermal Maximum 55 million years ago, when the global climate underwent

5800-402: The Arctic Ocean: Different authorities put various marginal seas in either the Arctic Ocean or the Atlantic Ocean, including: Hudson Bay , Baffin Bay , the Norwegian Sea , and Hudson Strait . The main islands and archipelagos in the Arctic Ocean are, from the prime meridian west: There are several ports and harbours on the Arctic Ocean. The ocean's Arctic shelf comprises

5916-408: The Canadian Archipelago. As noted, the process of ice formation and movement is a key driver in Arctic Ocean circulation and the formation of water masses. With this dependence, the Arctic Ocean experiences variations due to seasonal changes in sea ice cover. Sea ice movement is the result of wind forcing, which is related to a number of meteorological conditions that the Arctic experiences throughout

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6032-408: The European region of the Arctic Ocean was heavily contested : the Allied commitment to resupply the Soviet Union via its northern ports was opposed by German naval and air forces. Since 1954 commercial airlines have flown over the Arctic Ocean (see Polar route ). The Arctic Ocean occupies a roughly circular basin and covers an area of about 14,056,000 km (5,427,000 sq mi), almost

6148-410: The Fram Strait is what allows for both inflow and outflow on the Atlantic side of the Arctic Ocean. Because of this, it is influenced by the Coriolis force , which concentrates outflow to the East Greenland Current on the western side and inflow to the Norwegian Current on the eastern side. Pacific water also exits along the west coast of Greenland and the Hudson Strait (1–2 Sv), providing nutrients to

6264-489: The LGM, due to cold and dry conditions. Coastal environments during the Last Glacial Maximum were complex. The lowered sea level, and an isostatic bulge equilibrated with the depression beneath the Cordilleran Ice Sheet, exposed the continental shelf to form a coastal plain. While much of the coastal plain was covered with piedmont glaciers, unglaciated refugia supporting terrestrial mammals have been identified on Haida Gwaii , Prince of Wales Island , and outer islands of

6380-401: The Last Glacial Maximum after 30,000 years BP saw the expansion of alpine glaciers and continental ice sheets that blocked migration routes out of Beringia. By 21,000 years BP, and possibly thousands of years earlier, the Cordilleran and Laurentide ice sheets coalesced east of the Rocky Mountains , closing off a potential migration route into the center of North America. Alpine glaciers in

6496-497: The Last Glacial Maximum, climates in eastern Siberia fluctuated between conditions approximating present day conditions and colder periods. The pre-LGM warm cycles in Arctic Siberia saw flourishes of megafaunas. The oxygen isotope record from the Greenland Ice Cap suggests that these cycles after about 45,000 BP lasted anywhere from hundreds to between one and two thousand years, with greater duration of cold periods starting around 32,000 BP. The pollen record from Elikchan Lake, north of

6612-419: The Lomonosov Ridge, which appears to be continental crust separated from the Barents-Kara Shelf in the Paleocene and then starved of sediment. It may contain up to 10 billion barrels of oil. The Gakkel Ridge rift is also poorly understand and may extend into the Laptev Sea. In large parts of the Arctic Ocean, the top layer (about 50 m [160 ft]) is of lower salinity and lower temperature than

6728-444: The North American polar region goes back at least 17,000–50,000 years, during the Wisconsin glaciation . At this time, falling sea levels allowed people to move across the Bering land bridge that joined Siberia to northwestern North America (Alaska), leading to the Settlement of the Americas . Early Paleo-Eskimo groups included the Pre-Dorset ( c.  3200–850 BC ); the Saqqaq culture of Greenland (2500–800 BC);

6844-508: The Pacific coast broke up starting around 16,200 BP. The ice-free corridor to the interior of North America opened between 13,000 and 12,000 BP. Glaciation in eastern Siberia during the LGM was limited to alpine and valley glaciers in mountain ranges and did not block access between Siberia and Beringia. The paleoclimates and vegetation of eastern Siberia and Alaska during the Wisconsin glaciation have been deduced from high resolution oxygen isotope data and pollen stratigraphy . Prior to

6960-608: The average winter value of 15,600,000 km (6,023,200 sq mi). The seasonal variations are about 7,000,000 km (2,702,700 sq mi), with the maximum in April and minimum in September. The sea ice is affected by wind and ocean currents, which can move and rotate very large areas of ice. Zones of compression also arise, where the ice piles up to form pack ice. Icebergs occasionally break away from northern Ellesmere Island , and icebergs are formed from glaciers in western Greenland and extreme northeastern Canada. Icebergs are not sea ice but may become embedded in

7076-504: The beginning of the cooling period that led into the LGM. A compilation of archaeological site dates throughout eastern Siberia suggest that the cooling period caused a retreat of humans southwards. Pre-LGM lithic evidence in Siberia indicate a settled lifestyle that was based on local resources, while post-LGM lithic evidence indicate a more migratory lifestyle. A 2021 discovery of human footprints in relict lake sediments near White Sands National Park in New Mexico demonstrated there

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7192-475: The chronology of the controversial Pedra Furada rock shelter in Piauí , Brazil . More recently, studies at the archaeological sites Santa Elina (27000-10000 years BP) in the midwest, and Rincão I (20000-12000 years BP) in southeastern Brazil also show associations of evidence of human presence with sediments dating from before the LGM. A 2003 study dated evidence for the controlled use of fire to before 40,000 years ago. Additional evidence has been adduced from

7308-457: The coastal ranges and the Alaskan Peninsula isolated the interior of Beringia from the Pacific coast. Coastal alpine glaciers and lobes of Cordilleran ice coalesced into piedmont glaciers that covered large stretches of the coastline as far south as Vancouver Island and formed an ice lobe across the Straits of Juan de Fuca by 18,000 BP. Coastal alpine glaciers started to retreat around 19,000 BP while Cordilleran ice continued advancing in

7424-441: The collision of India with Eurasia, and the continued opening of the North Atlantic created new hydrocarbon traps. The seafloor began spreading from the Gakkel Ridge in the Paleocene Epoch and the Eocene Epoch, causing the Lomonosov Ridge to move farther from land and subside. Because of sea ice and remote conditions, the geology of the Arctic Ocean is still poorly explored. The Arctic Coring Expedition drilling shed some light on

7540-576: The deglaciated landscape increased slowly. The earliest possible viability of the ice-free corridor as a human migration route has been estimated at 11,500 BP. Birch forests were advancing across former herb tundra in Beringia by 17,000 BP in response to climatic amelioration, indicating increased productivity of the landscape. Analyses of biomarkers and microfossils preserved in sediments from Lake E5 and Burial Lake in northern Alaska suggest early humans burned Beringian landscapes as early as 34,000 years ago. The authors of these studies suggest that fire

7656-563: The development of human Y-chromosome DNA haplogroups (yDNA haplogroups ) and human mitochondrial DNA haplogroups (mtDNA haplogroups) characteristic of Native American populations. Models of molecular evolution rates were used to estimate the ages at which Native American DNA lineages branched off from their parent lineages in Asia and to deduce the ages of demographic events. One model (Tammetal 2007) based on Native American mtDNA Haplotypes (Figure 2) proposes that migration into Beringia occurred between 30,000 and 25,000 BP, with migration into

7772-472: The early 21st century, the models of the chronology of migration are divided into two general approaches. The first is the short chronology theory , that the first migration occurred after the LGM, which went into decline after about 19,000 years ago, and was then followed by successive waves of immigrants. The second theory is the long chronology theory, which proposes that the first group of people entered Beringia, including ice-free parts of Alaska, at

7888-454: The early human groups who hunted them. Bison , a type of megafauna, have been identified as an ideal candidate for the tracing of human migrations out of Europe because of both their abundance in North America as well as being one of the first megafauna for which ancient DNA was used to trace patterns of population movement. Unlike other types of fauna that moved between the Americas and Eurasia ( mammoths , horses , and lions ), Bison survived

8004-437: The explorers who travelled closer and closer to the pole reported, the polar ice cap is quite thick and persists year-round. Fridtjof Nansen was the first to make a nautical crossing of the Arctic Ocean, in the Fram Expedition from 1893 to 1896. The first surface crossing of the ocean was led by Wally Herbert in 1969, in a dog sled expedition from Alaska to Svalbard , with air support. The first nautical transit of

8120-401: The food from Eurasia to the Americas – part of the reason why tracing megafaunal DNA is so helpful for garnering insight to these migratory patterns. The grey wolf originated in the Americas and migrated into Eurasia prior to the Last Glacial Maximum – during which it was believed that remaining populations of the grey wolf residing in North America faced extinction and were isolated from

8236-440: The formation of Atlantic Deep Water. The overturning of this water plays a key role in global circulation and the moderation of climate. In the depth range of 150–900 m (490–2,950 ft) is a water mass referred to as Atlantic Water. Inflow from the North Atlantic Current enters through the Fram Strait, cooling and sinking to form the deepest layer of the halocline, where it circles the Arctic Basin counter-clockwise. This

8352-571: The genetic profiles of the Hokkaido Jōmon skeletons and the modern Ainu illustrates another uncertainty in source models derived from modern DNA samples. The development of high-resolution genomic analysis has provided opportunities to further define Native American subclades and narrow the range of Asian subclades that may be parent or sister subclades. The common occurrence of the mtDNA Haplogroups A, B, C, and D among eastern Asian and Native American populations has long been recognized, along with

8468-635: The geologic association of bones at the Bluefish Cave and Old Crow Flats sites, and the related Bonnet Plume site, have been called into question. No evidence of human remains have been discovered at these sites. In addition to disputed archaeological sites, support for pre-LGM human presence has been found in lake sediment records of northern Alaska. Biomarker and microfossil analyses of sediments from Lake E5 and Burial Lake in suggest human presence in eastern Beringia as early as 34,000 years ago. These analyses are indeed compelling in that they corroborate

8584-456: The ice has been quoted at 50%. The US National Snow and Ice Data Center (NSIDC) uses satellite data to provide a daily record of Arctic sea ice cover and the rate of melting compared to an average period and specific past years, showing a continuous decline in sea ice extent. In September 2012, the Arctic ice extent reached a new record minimum. Compared to the average extent (1979–2000), the sea ice had diminished by 49%. Human habitation in

8700-609: The ice sheets, the oldest such sites occur in association with the Clovis complex. If humans managed to breach the continental ice sheets significantly before 13,000 BP, there should be clear evidence for it in the form of at least some stratigraphically discrete archaeological components with a relatively high artifact count. So far, no such evidence exists." Genetic studies have used high resolution analytical techniques applied to DNA samples from modern Native Americans and Asian populations regarded as their source populations to reconstruct

8816-497: The increasing influence of Atlantic water heat in melting sea ice in the eastern Arctic. The most recent estimates, for 2016–2018, indicate the oceanic heat flux to the surface has now overtaken the atmospheric flux in the eastern Eurasian Basin. Over the same period the weakening halocline stratification has coincided with increasing upper ocean currents thought to be associated with declining sea ice, indicate increasing mixing in this region. In contrast direct measurements of mixing in

8932-761: The inferences made from the Bluefish Cave and Old Crow Flats sites. In 2020, evidence emerged for a new pre-LGM site in North-Central Mexico . Chiquihuite cave , an archaeological site in Zacatecas State, has been dated to 26,000 years BP based on numerous lithic artefacts discovered there. However, there is scholarly debate over whether the artifacts should be considered evidence of human activity or if they were formed naturally. No evidence of human DNA or hearth have been unearthed. Pre-LGM human presence in South America rests partly on

9048-457: The location where the admixture took place. However, a third theory, the "Beringian standstill hypothesis", suggests that East Asians instead migrated north to Northeastern Siberia, where they mixed with ANE, and later diverged in Beringia, where distinct Native American lineages formed. This theory is supported by maternal and nuclear DNA evidence. According to Grebenyuk, after 20,000 BP,

9164-531: The lower Amur region suggests a source population from that region distinct from the Altai-Baikal source populations, where sampling did not reveal those two particular subclades. The conclusions regarding Subhaplogroup D1 indicating potential source populations in the lower Amur and Hokkaido areas stand in contrast to the single-source migration model. Subhaplogroup D4h3 has been identified among Han Chinese . Subhaplogroup D4h3 from China does not have

9280-525: The modern Native American phenotype. Archaeogenetic studies do not support a two-wave model or the Paleoamerican hypothesis of an Australo-Melanesian origin, and firmly assign all Paleo-Indians and modern Native Americans to one ancient population that entered the Americas in a single migration from Beringia. Only in one ancient specimen (Lagoa Santa) and a few modern populations in the Amazon region,

9396-483: The more fanciful cartographers, tended to leave the region blank, with only fragments of known coastline sketched in. This lack of knowledge of what lay north of the shifting barrier of ice gave rise to a number of conjectures. In England and other European nations, the myth of an " Open Polar Sea " was persistent. John Barrow , longtime Second Secretary of the British Admiralty , promoted exploration of

9512-470: The morphology of Luzia Woman fossil, which was described as Australo-Melanesian . This interpretation was challenged in a 2003 review which concluded the features in question could also have arisen by genetic drift. In November 2018, scientists of the University of São Paulo and Harvard University released a study that contradicts the alleged Australo-Melanesian origin of Luzia. Using DNA sequencing,

9628-482: The most closely related subclades grow more specific. Subhaplogroups D1 and D4h3 have been regarded as Native American specific based on their absence among a large sampling of populations regarded as potential descendants of source populations, over a wide area of Asia. Among the 3,764 samples, the Sakhalin –lower Amur region was represented by 61 Oroks . In another study, Subhaplogroup D1a has been identified among

9744-497: The north polar regions remained largely unexplored and their geography conjectural. Pytheas of Massilia recorded an account of a journey northward in 325 BC, to a land he called " Eschate Thule ", where the Sun only set for three hours each day and the water was replaced by a congealed substance "on which one can neither walk nor sail". He was probably describing loose sea ice known today as " growlers " or "bergy bits"; his "Thule"

9860-400: The north pole was made in 1958 by the submarine USS Nautilus , and the first surface nautical transit occurred in 1977 by the icebreaker NS Arktika . Since 1937, Soviet and Russian manned drifting ice stations have extensively monitored the Arctic Ocean. Scientific settlements were established on the drift ice and carried thousands of kilometres by ice floes . In World War II ,

9976-409: The only possibly recoverable remnants of humans living in Alaska during the last Glacial period. At Old Crow Flats, mammoth bones have been found that are broken in distinctive ways indicating human butchery. The radiocarbon dates on these vary between 25,000 and 40,000 BP. Also, stone microflakes have been found in the area indicating tool production. However, the interpretations of butcher marks and

10092-578: The pack ice. Icebergs pose a hazard to ships, of which the Titanic is one of the most famous. The ocean is virtually icelocked from October to June, and the superstructure of ships are subject to icing from October to May. Before the advent of modern icebreakers, ships sailing the Arctic Ocean risked being trapped or crushed by sea ice (although the Baychimo drifted through the Arctic Ocean untended for decades despite these hazards). The Arctic Ocean

10208-640: The period of the Last Glacial Maximum along with genetic evidence found from early human remains in the Americas provides evidence to support pre-Clovis migrations into the Americas. The Native American source population was formed in Siberia by the mixing of two distinct populations: Ancient North Eurasians and an ancient East Asian (ESEA) population. According to Jennifer Raff, the Ancient North Eurasian population mixed with

10324-490: The possible date of the first peopling of the Americas. Academics generally believe that humans reached North America south of the Laurentide Ice Sheet at some point between 15,000 and 20,000 years ago. Some new controversial archaeological evidence suggests the possibility that human arrival in the Americas may have occurred prior to the Last Glacial Maximum more than 20,000 years ago. During

10440-503: The presence of haplogroup X . As a whole, the greatest frequency of the four Native American associated haplogroups occurs in the Altai - Baikal region of southern Siberia. Some subclades of C and D closer to the Native American subclades occur among Mongolian, Amur, Japanese, Korean, and Ainu populations. With further definition of subclades related to Native American populations, the requirements for sampling Asian populations to find

10556-457: The presence of the A subtype. The finding ignited controversy, with contention that the sample DNA was insufficiently complete for the conclusion and that the result reflected modern contamination. However, a re-analysis indicated that the DNA sequences were consistent with, but not definitely from, the "cosmopolitan clade" (subtype A). The presence of subtypes A and B in the Americas is suggestive of

10672-421: The rate grew more rapid. The inland Cordilleran and Laurentide ice sheets retreated more slowly than did the coastal glaciers. Opening of an ice-free corridor did not occur until after 13,000 to 12,000 BP. The early environment of the ice-free corridor was dominated by glacial outwash and meltwater, with ice-dammed lakes and periodic flooding from the release of ice-dammed meltwater. Biological productivity of

10788-590: The region from 1818 to 1845 in search of this. In the United States in the 1850s and 1860s, the explorers Elisha Kane and Isaac Israel Hayes both claimed to have seen part of this elusive body of water. Even quite late in the century, the eminent authority Matthew Fontaine Maury included a description of the Open Polar Sea in his textbook The Physical Geography of the Sea (1883). Nevertheless, as all

10904-438: The rest of the population. This, however, may not be the case. Radiocarbon dating of ancient grey wolf remains found in permafrost deposits in Alaska show a continuous exchange of population from 12,500 radiocarbon years BP to beyond radiocarbon dating capabilities. This indicates that there was viable passage for grey wolf populations to exchange between the two continents. These faunas' ability to exchange populations during

11020-520: The rest. It remains relatively stable because the salinity effect on density is bigger than the temperature effect. It is fed by the freshwater input of the big Siberian and Canadian rivers ( Ob , Yenisei , Lena , Mackenzie ), the water of which quasi floats on the saltier, denser, deeper ocean water. Between this lower salinity layer and the bulk of the ocean lies the so-called halocline , in which both salinity and temperature rise with increasing depth. Because of its relative isolation from other oceans,

11136-581: The results showed that Luzia's ancestry was entirely Native American. Stones described as probable tools, hammerstones and anvils , have been found in southern California , at the Cerutti Mastodon site , that are associated with a mastodon skeleton which appeared to have been processed by humans. The mastodon skeleton was dated by thorium-230/uranium radiometric analysis, using diffusion–adsorption–decay dating models, to around 130 thousand years ago. No human bones were found and expert reaction

11252-597: The retreat of game species with the onset of the LGM has been proposed to explain the lack of archaeological sites in that region dating to the LGM. The pollen record from the Alaskan side shows shifts between herb/shrub and shrub tundra prior to the LGM, suggesting less dramatic warming episodes than those that allowed forest colonization on the Siberian side. Diverse, though not necessarily plentiful, megafauna were present in those environments. Herb tundra dominated during

11368-663: The role of salinity in density. When water reaches the basin, it is pushed by strong winds into a large circular current called the Beaufort Gyre . Water in the Beaufort Gyre is far less saline than that of the Chukchi Sea due to inflow from large Canadian and Siberian rivers. The final defined water mass in the Arctic Ocean is called Arctic Surface Water and is found in the depth range of 150–200 m (490–660 ft). The most important feature of this water mass

11484-457: The same geographic implication as Subhaplotype D1a from Amur-Hokkaido, so its implications for source models are more speculative. Its parent lineage, Subhaplotype D4h, is believed to have emerged in East Asia, rather than Siberia, around 20,000 BP. Subhaplogroup D4h2, a sister clade of D4h3, has also been found among Jōmon skeletons from Hokkaido. D4h3 has a coastal trace in the Americas. X

11600-462: The sea that sink over the continental shelf into the western Arctic Ocean and create a halocline. This water is met by Greenland Sea Deep Water, which forms during the passage of winter storms. As temperatures cool dramatically in the winter, ice forms, and intense vertical convection allows the water to become dense enough to sink below the warm saline water below. Arctic Bottom Water is critically important because of its outflow, which contributes to

11716-467: The shelf region that begins as inflow from the Pacific passes through the narrow Bering Strait at an average rate of 0.8 Sverdrups and reaches the Chukchi Sea . During the winter, cold Alaskan winds blow over the Chukchi Sea, freezing the surface water and pushing this newly formed ice out to the Pacific. The speed of the ice drift is roughly 1–4 cm/s. This process leaves dense, salty waters in

11832-411: The size of Antarctica . The coastline is 45,390 km (28,200 mi) long. It is the only ocean smaller than Russia , which has a land area of 16,377,742 km (6,323,482 sq mi). The Arctic Ocean is surrounded by the land masses of Eurasia (Russia and Norway), North America ( Canada and the U.S. state of Alaska), Greenland, and Iceland . Note: Some parts of the areas listed in

11948-478: The summer months. There is also evidence that the drift is associated with the phase of the Arctic Oscillation and Atlantic Multidecadal Oscillation . Much of the Arctic Ocean is covered by sea ice that varies in extent and thickness seasonally. The mean extent of the Arctic sea ice has been continuously decreasing in the last decades, declining at a rate of currently 12.85% per decade since 1980 from

12064-664: The summer, the SLP contrast is smaller, producing weaker winds. A final example of seasonal pressure system movement is the low pressure system that exists over the Nordic and Barents Seas. It is an extension of the Icelandic Low , which creates cyclonic ocean circulation in this area. The low shifts to centre over the North Pole in the summer. These variations in the Arctic all contribute to ice drift reaching its weakest point during

12180-696: The table are located in the Atlantic Ocean . Other consists of Gulfs , Straits , Channels and other parts without specific names and excludes Exclusive Economic Zones . The Arctic Ocean is connected to the Pacific Ocean by the Bering Strait and to the Atlantic Ocean through the Greenland Sea and Labrador Sea . (The Iceland Sea is sometimes considered part of the Greenland Sea, and sometimes separate.) The largest seas in

12296-475: The upper 100–150 m (330–490 ft) of ocean water cools to the freezing point for sea ice to form. In the winter, the relatively warm ocean water exerts a moderating influence, even when covered by ice. This is one reason why the Arctic does not experience the extreme temperatures seen on the Antarctic continent . There is considerable seasonal variation in how much pack ice of the Arctic ice pack covers

12412-404: The use of dated fossil DNA to calibrate molecular evolution rates. Although there is no archaeological evidence that can be used to direct support a coastal migration route during the Last Glacial Maximum , genetic analysis has been used to support this thesis. In addition to human genetic lineage, megafaunal DNA lineage can be used to trace movements of megafauna – large mammalian – as well as

12528-553: The western Arctic indicate the Atlantic water heat remains isolated at intermediate depths even under the 'perfect storm' conditions of the Great Arctic Cyclone of 2012 . Waters originating in the Pacific and Atlantic both exit through the Fram Strait between Greenland and Svalbard Island, which is about 2,700 m (8,900 ft) deep and 350 km (220 mi) wide. This outflow is about 9 Sv. The width of

12644-628: The world; it holds large oil and gas reserves. The Chukchi shelf forms the border between Russian and the United States as stated in the USSR–USA Maritime Boundary Agreement . The whole area is subject to international territorial claims . The Chukchi Plateau extends from the Chukchi Sea Shelf. An underwater ridge , the Lomonosov Ridge , divides the deep sea North Polar Basin into two oceanic basins :

12760-547: The year. For example, the Beaufort High—an extension of the Siberian High system—is a pressure system that drives the anticyclonic motion of the Beaufort Gyre. During the summer, this area of high pressure is pushed out closer to its Siberian and Canadian sides. In addition, there is a sea level pressure (SLP) ridge over Greenland that drives strong northerly winds through the Fram Strait, facilitating ice export. In

12876-669: Was a verifiable human presence in the region dating back to the LGM between 18,000 and 26,000 years ago. Later studies, reported in October 2023, confirmed that the age of the human footprints to be "up to 23,000 years old". The Clovis-first advocates have not accepted the veracity of these findings. In 2022, they said, "The oldest evidence for archaeological sites in the New World with large numbers of artifacts occurring in discrete and minimally disturbed stratigraphic contexts occur in eastern Beringia between 13,000 and 14,200 BP. South of

12992-415: Was accelerated as sea levels rose and floated glacial termini. It has been estimated that the coast range was fully ice-free between 16,000 and 15,000 BP. Littoral marine organisms colonized shorelines as ocean water replaced glacial meltwater. Replacement of herb/shrub tundra by coniferous forests was underway by 15,000 BP north of Haida Gwaii. Eustatic sea level rise caused flooding, which accelerated as

13108-429: Was found to carry the deepest branch of the X2a haplogroup, and he did not have any European ancestry that would be expected for a European origin of the lineage. The Human T cell Lymphotrophic Virus 1 ( HTLV-1 ) is a virus transmitted through exchange of bodily fluids and from mother to child through breast milk. The mother-to-child transmission mimics a hereditary trait, although such transmission from maternal carriers

13224-458: Was mixed; claims of tools and bone processing were called "not plausible" by Prof. Tom Dillehay . The Yana River Rhino Horn site (RHS) has dated human occupation of eastern Arctic Siberia to 31,300 BP. That date has been interpreted by some as evidence that migration into Beringia was imminent, lending credence to occupation of Beringia during the LGM. However, the Yana RHS date is from

13340-674: Was probably Norway , though the Faroe Islands or Shetland have also been suggested. Early cartographers were unsure whether to draw the region around the North Pole as land (as in Johannes Ruysch 's map of 1507, or Gerardus Mercator 's map of 1595) or water (as with Martin Waldseemüller 's world map of 1507). The fervent desire of European merchants for a northern passage, the Northern Sea Route or

13456-505: Was used as means of hunting megafauna. The Indigenous peoples of the Americas have an ascertained archaeological presence in the Americas dating back to about 15,000 years ago. More recent research, however, suggests a human presence dating to between 18,000 and 26,000 years ago, during the Last Glacial Maximum. There remain uncertainties regarding the precise dating of individual sites and regarding conclusions drawn from population genetics studies of contemporary Native Americans. In

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