Cosmogenic 36Cl dating of the Foothills erratics train, Alberta, Canada

Jackson, L E; Phillips, Fred M.; Shimamura, K; Little, E C

doi:10.1130/0091-7613(1997)025<0195:ccdotf>2.3.co;2

Cited by 88 publications

(61 citation statements)

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“…1950) (9). Ice sheet coalescence would have formed an impenetrable barrier to terrestrial dispersals between Beringia to the north and interior North America to the south that lasted at least until glaciers retreated near the end of the Pleistocene.…”

mentioning

confidence: 99%

Bison phylogeography constrains dispersal and viability of the Ice Free Corridor in western Canada

Heintzman

Froese

Ives

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

148

133

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The Ice Free Corridor has been invoked as a route for Pleistocene human and animal dispersals between eastern Beringia and more southerly areas of North America. Despite the significance of the corridor, there are limited data for when and how this corridor was used. Hypothetical uses of the corridor include: the first expansion of humans from Beringia into the Americas, northward postglacial expansions of fluted point technologies into Beringia, and continued use of the corridor as a contact route between the north and south. Here, we use radiocarbon dates and ancient mitochondrial DNA from late Pleistocene bison fossils to determine the chronology for when the corridor was open and viable for biotic dispersals. The corridor was closed after ∼23,000 until 13,400 calendar years ago (cal y BP), after which we find the first evidence, to our knowledge, that bison used this route to disperse from the south, and by 13,000 y from the north. Our chronology supports a habitable and traversable corridor by at least 13,000 cal y BP, just before the first appearance of Clovis technology in interior North America, and indicates that the corridor would not have been available for significantly earlier southward human dispersal. Following the opening of the corridor, multiple dispersals of human groups between Beringia and interior North America may have continued throughout the latest Pleistocene and early Holocene. Our results highlight the utility of phylogeographic analyses to test hypotheses about paleoecological history and the viability of dispersal routes over time.

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mentioning

confidence: 99%

Bison phylogeography constrains dispersal and viability of the Ice Free Corridor in western Canada

Heintzman

Froese

Ives

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

148

133

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“…Although an ice-free corridor would have existed between the Laurentide (LIS) and Cordilleran (CIS) ice sheets during buildup and retreat, most researchers now agree that ice sheet confluence and mutual deflection did occur along the Rocky Mountain Front during the Last Glacial Maximum (LGM) (Levson and Rutter, 1996;Jackson et al, 1997;Dyke, 2004;Bednarski and Smith, 2007). The Athabasca River valley area of south-west Alberta was a key location in resolving this debate, since ice-flow indicators clearly demonstrate that a major Late Wisconsinan CIS outlet glacier emerging from the valley converged with the LIS and was deflected to the south-east ( Fig.…”

Section: Introductionmentioning

confidence: 99%

“…1; Roed, 1975;Levson and Rutter, 1996). This south-easterly deflection of confluent ice flows is delineated by the dispersal pattern of lithologically distinctive glacially transported debris, which includes a train of metamorphic erratics originating west of the Rocky Mountains, and the Foothills erratics train which comprises Rocky Mountains derived quartzites that extends from the Athabasca Valley as far south as the international border (Stalker, 1956;Roed et al, 1967;Jackson et al, 1997).…”

Section: Introductionmentioning

confidence: 99%

Reconstructing the confluence zone between Laurentide and Cordilleran ice sheets along the Rocky Mountain Foothills, south‐west Alberta

Utting

Atkinson

Pawley

et al. 2016

J Quaternary Science

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Landform mapping near the Athabasca valley was fundamental to determining whether or not the Late Wisconsinan Laurentide and Cordilleran Ice Sheets coalesced. In this paper we examine the detailed landform record using new LiDAR digital elevation and hillshade models of the area of confluence and eventual desuturing of these ice sheets. This work reveals an earlier more extensive Cordilleran advance prior to coalescence with the LIS. When the ice sheets coalesced, the flow pattern is dominated by ice flow along the mountain front, with Cordilleran ice flowing out of major trunk valleys but Laurentide ice flowing into the Foothills up smaller valleys. This flow pattern implies that when the ice sheets coalesced the CIS was already waning, or at least was not at its maximum. Deglaciation was interrupted by several re-advances, likely related to the destabilizing effect of proglacial lakes along the ice margin.

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“…Cosmogenic isotope methods have recently been applied to late Wisconsin landscapes in New England (Larsen, 1996), the Great Lakes region , and along the southwestern LIS margin (Jackson et al, 1997(Jackson et al, , 1999. Larsen (1996) dated a boulder resting on the LGM end moraine in New Jersey and estimated its exposure time as about 21,500 yr, consistent with the radiocarbon chronology.…”

Section: Chronology and Climate Historymentioning

confidence: 91%

“…They also found that bedrock near the ice margin contained inherited isotopes that made cosmogenic dating near (within 30 km) the margin impossible. Jackson et al (1997Jackson et al ( , 1999 showed that the southwestern LIS margin reached its greatest extent during the LGM sometime before 18,000 yr ago. These methods hold the promise of more closely limiting the age of glacial events if the problems of inheritance can be overcome, and uncertainty in isotope production rates can be reduced.…”

Section: Chronology and Climate Historymentioning

confidence: 99%