scholarly journals Initial peopling of North America: paleogeography and archaeology

2019 ◽  
pp. 131-140
Author(s):  
S. A. Vasilyev
Keyword(s):  
North America ◽  
Land Bridge ◽  
Southeastern Part ◽  
Single Wave ◽  
The North ◽  
Human Movements ◽  
The Pacific ◽  
The Usa ◽  
The Last Glacial Maximum ◽  
The Last Glacial

The paper contains a summary of the new data relevant to the time and routes of the first peopling of the New World. The first unambiguous traces of humans are dated by the time span after the Last Glacial Maximum. The chronology and orientation of prehistoric migrations depended on the Late Pleistocene paleogeography. Instead of a postulated single wave of migration oriented from NW to SE from the Bering Land Bridge via the Mackenzie ice-free corridor to the territory lying southwards from the ice sheets we argue about a complicated picture of human movements of different age and direction. It seems that the earliest inhabitants penetrated from Beringia to the main area of North America following the Pacific coast and later dispersed to the east. The migration along the Mackenzie ice-free corridor should have place later. The Clovis culture seems to originate in the southeastern part of the USA territory then dispersing in northern and western directions along the whole continent. The Final Pleistocene saw the ‘inverse’ migration of the Paleoindians to the north, along the Mackenzie corridor to Beringia.

scholarly journals The cave-dwelling dipluran (Diplura, Campodeidae) on the edge of the Last Glacial Maximum in Vancouver Island caves, North America (Canada)

2019 ◽  
Vol 29 ◽  
pp. 59-77 ◽  
Author(s):  
Alberto Sendra ◽  
Craig Wagnell
Keyword(s):  
North America ◽  
Last Glacial Maximum ◽  
Vancouver Island ◽  
Glacial Maximum ◽  
Land Bridge ◽  
Last Glacial ◽  
The North ◽  
Body Distribution ◽  
The Last Glacial Maximum ◽  
The Last Glacial

A new cave-dwelling dipluran of the North American endemic genus Haplocampa is described, coming from a couple of caves excavated in a small limestone karstic area near Port Alberni, Vancouver Island (British Columbia, Canada). To Haplocampa belong five soil-dwelling species. L. M. Ferguson cited no less than eight more species living in soil and cave habitats in several US states but without producing any formal descriptions. Haplocampa, in spite of its large lateral crests on the unequal claws, has clear taxonomical features as a Campodeinae and is closely related with the cave-dwelling Pacificampa and Eumesocampa genera, due to sharing similar macrosetae body distribution and absence or reduction of the lateral process. The new proposed species, Haplocampawagnelli Sendra, sp. n., is rather interesting for its troglomorphic features: antennae with 32 antennomeres; olfactory chemoreceptors, each a multiperforated, folded-spiral structure; and numerous gouge sensilla. In addition, it is one of the northernmost troglomorphic species to have colonised – presumably recently – an area occupied by the Late Wisconsinian North America ice sheet during the Last Glacial Maximum. Furthermore, the close affinities between Haplocampa, Pacificampa (from caves in the extreme east of continental Asia and the southern Japanese Islands), Metriocampa (from the east of Asia and North America) and Eumesocampa (endemic to North America) suggest probable dispersal events over the Bering Land Bridge.

On thin ice: problems with Stanford and Bradley's proposed Solutrean colonisation of North America

Antiquity ◽  
2014 ◽  
Vol 88 (340) ◽  
pp. 606-613 ◽  
Author(s):  
Michael J. O'Brien ◽  
Matthew T. Boulanger ◽  
Mark Collard ◽  
Briggs Buchanan ◽  
Lia Tarle ◽  
...  
Keyword(s):  
North America ◽  
Iberian Peninsula ◽  
North Atlantic ◽  
Food Supply ◽  
Ice Shelf ◽  
Southern France ◽  
The North ◽  
The North Atlantic ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Across Atlantic ice: the origin of America's Clovis culture(Stanford & Bradley 2012) is the latest iteration of a controversial proposal that North America was first colonised by people from Europe rather than from East Asia, as most researchers accept. The authors, Dennis Stanford and Bruce Bradley, argue that Solutrean groups from southern France and the Iberian Peninsula used watercraft to make their way across the North Atlantic and into North America during the Last Glacial Maximum (LGM). According to Stanford and Bradley, this 6000km journey was facilitated by a continuous ice shelf that provided fresh water and a food supply.AcrossAtlantic ice has received a number of positive reviews. Shea (2012: 294), for example, suggests that it is “an excellent example of hypothesis-building in the best tradition of processual archaeology. It challenges American archaeology in a way that will require serious research by its opponents”. Runnels (2012) is equally enthusiastic.

scholarly journals A Geophysical and Climatological Assessment of New Guinea — Implications for the Origins of Saccharum

2020 ◽  
Author(s):  
Dyfed Lloyd Evans
Keyword(s):  
Global Climate ◽  
New Guinea ◽  
North Coast ◽  
Tsunami Modelling ◽  
The North ◽  
The Pacific ◽  
Human Colonization ◽  
The Last Glacial Maximum ◽  
Modern Form ◽  
The Last Glacial

AbstractAny assessment of whether or not Saccharum species are native or introduced in New Guinea require an evolutionary (in a geological sense), geophysical and climatological assessment of the island. Like many of the land masses circling the Pacific (in the volcanically active region known as the ‘ring of fire’) New Guinea is geologically young, with the island in its modern form not pre-dating 2 Ma. Novel modelling of the 74 ka youngest Toba supereruption indicates a potential extinction level tsunami and loss of habitat. The late Pleistocene megafaunal mass extinction and the last glacial maximum (33–16 ka) are two global effects that would have significantly altered the flora on New Guinea; though the implications of these events on New Guinea have not previously been studied. Even if the genus Saccharum was established on the island during pre-historic times the consequences of Toba and other global climate change events means that it would have been eliminated from New Guinea and would have had to be re-introduced during the period of human colonization. Indeed, given the evolution of Saccharum’s immediate ancestors in Africa and Indochina it is most parsimonious to conclude that it was never native to New Guinea, but was introduced by humans relatively recently.Little work has been done on palaeotsunami evidence and ancient tsunami modelling in New Guinea. However, the recent recognition that the Aitape skull (dating to about 6 ka) may have been the victim of a tsunami (Goff et al. 2017) show that, in the past, tsunami have pen etrated significantly (about 10 km in this case) into the interior of the island to have a profound effect on biodiversity. This tsunami would have left the north coast of the island impoverished of plant life for several decades after.

scholarly journals Northern Westerlies during the Last Glacial Maximum: Results from CMIP5 Simulations

2018 ◽  
Vol 31 (3) ◽  
pp. 1135-1153 ◽  
Author(s):  
Na Wang ◽  
Dabang Jiang ◽  
Xianmei Lang
Keyword(s):  
North America ◽  
Last Glacial Maximum ◽  
Lower Troposphere ◽  
Glacial Maximum ◽  
Jet Stream ◽  
Last Glacial ◽  
The North ◽  
Poleward Shift ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Abstract Based upon simulations from phase 5 of the Coupled Model Intercomparison Project (CMIP5), the vertical and regional characteristics of the northern westerlies during the Last Glacial Maximum (LGM) are investigated in this study. At the Northern Hemispheric scale, all nine available models simulate a poleward shift of the 200-hPa jet, and eight models simulate an equatorward shift of the 850-hPa jet compared to the preindustrial period; these shifts are of approximately 2°–3° latitude for the arithmetic multimodel mean. The upper-tropospheric cooling in the tropics, possibly due to reduced latent heat release, is expected to account for the poleward shift of the 200-hPa jet through the thermal wind relationship. Changes in the midlatitude baroclinic instability in response to the amplified polar cooling are associated with the jet stream in the lower troposphere through anomalous eddy activity. In particular, the types of predominant baroclinic eddies are regionally dependent. The behavior of the 850-hPa jet over the North Pacific is steered by transient eddies and characterized by a southward displacement during the LGM. By contrast, the remarkable enhancement of the North Atlantic jet stream throughout the troposphere is associated with the notably increased stationary eddy momentum convergence, presumably due to the presence of the Laurentide ice sheet over North America. In comparison with the proxy records, although there is no observational evidence explicitly indicating changes of the upper-level northern westerlies, the simulated LGM 850-hPa westerly wind field is indirectly concordant with the reconstructed moisture conditions over the Mediterranean region and southwestern North America.

scholarly journals A simple mixing explanation for late Pleistocene changes in the Pacific-South Atlantic benthic δ<sup>13</sup>C gradient

2009 ◽  
Vol 5 (6) ◽  
pp. 2607-2630 ◽  
Author(s):  
L. E. Lisiecki
Keyword(s):  
Late Pleistocene ◽  
Deep Water ◽  
North Pacific ◽  
Deep Ocean ◽  
South Atlantic ◽  
The North ◽  
The Pacific ◽  
The Last Glacial Maximum ◽  
The North Pacific ◽  
The Last Glacial

Abstract. The fact that the deep-ocean benthic δ13C minimum shifted from the North Pacific to the South Atlantic during the Last Glacial Maximum is often interpretted as evidence of a change in deep water circulation, such as the development of deep water ventilation in the North Pacific. This study re-evaluates the implications of changes in benthic δ13C gradients by comparing Pacific Deep Water (PDW) δ13C measurements with the values expected for the null hypothesis that PDW ventilation sources remained unchanged throughout the Late Pleistocene. The δ13C compositions of PDW, Northern Component Water (NCW) and Southern Component Water (SCW) are estimated from regional benthic δ13C stacks of 3–6 sites. Changes in PDW δ13C and PDW-SCW δ13C gradients over the past 800 kyr are found to be well described by a constant mixture of 60% NCW and 40% SCW plus a constant Pacific "age" offset of −0.5‰. Thus, an additional ventilation source for glacial PDW (e.g., in the North Pacific) cannot be inferred solely on the basis of changes in the Pacific-South Atlantic benthic δ13C gradient.

scholarly journals A simple mixing explanation for late Pleistocene changes in the Pacific-South Atlantic benthic δ<sup>13</sup>C gradient

2010 ◽  
Vol 6 (3) ◽  
pp. 305-314 ◽  
Author(s):  
L. E. Lisiecki
Keyword(s):  
Late Pleistocene ◽  
Deep Water ◽  
North Pacific ◽  
Deep Ocean ◽  
South Atlantic ◽  
The North ◽  
The Pacific ◽  
The Last Glacial Maximum ◽  
The North Pacific ◽  
The Last Glacial

Abstract. The fact that the deep-ocean benthic δ13C minimum shifted from the North Pacific to the South Atlantic during the Last Glacial Maximum is often interpretted as evidence of a change in deep water circulation, such as the development of deep water ventilation in the North Pacific or a decrease in Southern Ocean overturning. This study re-evaluates the implications of changes in benthic δ13C gradients by comparing Pacific Deep Water (PDW) δ13C measurements with the values expected for the null hypothesis that PDW ventilation sources remained unchanged throughout the Late Pleistocene. The δ13C compositions of PDW, Northern Component Water (NCW) and Southern Component Water (SCW) are estimated from regional benthic δ13C stacks of 3–6 sites. Changes in PDW δ13C and PDW-SCW δ13C gradients over the past 800 kyr are found to be well described by a constant mixture of 60% NCW and 40% SCW plus a constant Pacific remineralization offset of −0.5‰. Thus, a change in PDW ventilation cannot be inferred solely on the basis of changes in the Pacific-South Atlantic benthic δ13C gradient.

Geographic patterns of genetic diversity in North American trees: a continent-wide analysis

2021 ◽  
Author(s):  
Andrew V. Gougherty
Keyword(s):  
Genetic Diversity ◽  
Population Genetics ◽  
North America ◽  
North American ◽  
Tree Species ◽  
Geographic Patterns ◽  
Study Characteristics ◽  
Dispersal Traits ◽  
The Last Glacial Maximum ◽  
The Last Glacial

In the northern hemisphere, many species have been reported to have greater genetic diversity in southern populations than northern populations - ostensibly due to migration northward following the last glacial maximum (LGM). The generality of this pattern, while well-established for some taxa, remains unclear for North American trees. To address this issue, I collected published population genetics data for 73 North American tree species, and tested whether genetic diversity was associated with latitude or longitude and whether geographic trends were associated with dispersal traits, range or study characteristics. I found there were no general geographic patterns in genetic diversity, and the strength of the geographic gradients were not associated with any species or study characteristics. Species in the northern and western regions of North America tended to have more species with genetic diversity that declined with latitude, but most species had no significant trend. This work shows that North American trees have complex, individualistic, patterns of genetic diversity that may negate explanation by any particular dispersal trait or range characteristic.

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