Early retreat of the Alaska Peninsula Glacier Complex and the implications for coastal migrations of First Americans

Misarti, Nicole; Finney, Bruce P.; Jordan, James W.; Maschner, Herbert D. G.; Addison, Jason A.; Shapley, Mark; Krumhardt, Andrea P.; Begét, James E.

doi:10.1016/j.quascirev.2012.05.014

Cited by 63 publications

(36 citation statements)

References 31 publications

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“…Surface exposure ages from islands to the north of Haida Gwaii demonstrate that ice retreat occurred by ca. 17.0 ka (Lesnek et al, 2018), similar to deglacial ages from lakes on the Alaskan Peninsula (Misarti et al, 2012). Marine records indicate that ice reached the edge of the continental shelf at its last maximum and formed an extensive margin across Queen Charlotte Sound (Barrie & Conway, 1999, 2002aBlaise et al, 1990;Davies et al, 2011;.…”

Section: Introductionsupporting

confidence: 53%

Retreat of the Western Cordilleran Ice Sheet Margin During the Last Deglaciation

Darvill

Menounos

Goehring

et al. 2018

Geophysical Research Letters

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The timing of Cordilleran Ice Sheet deglaciation along the central coast of British Columbia, Canada, informs climate forcing and early human migration. Thirty-two 10 Be exposure ages from glacial erratics and local bedrock on the western margin of the former ice sheet represent the earliest exposure ages for the Cordilleran Ice Sheet during the last deglaciation. These data show the western ice margin was retreating by 18.1 ± 0.2 ka, consistent with the global record of ice mass loss. In contrast, parts of the southern margin reached a maximum at ca. 17.6-16.6 ka, and our data demonstrate a diachronous response of the Cordilleran Ice Sheet during deglaciation. We also show that a low altitude site was exposed by at least 17.7 ± 0.3 ka, implying that numerous ice-free areas existed along the coastal margin by this time, providing a viable route for the first humans entering the Americas.Plain Language Summary Large ice sheets have advanced and retreated multiple times over the last several hundred thousand years in response to cyclical changes in incoming solar radiation. The Cordilleran Ice Sheet, which once covered much of western Canada, was thought to have advanced and retreated later than others during its last major cycle. The retreat of this ice sheet also opened routes that allowed the first people to enter the Americas. We show that the western margin of the ice sheet retreated earlier than previously thought. Other margins of the ice sheet advanced later, creating a complex picture through time. The early retreat of the western ice margin exposed numerous islands that could have been used by early people migrating southward.

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Section: Introductionsupporting

confidence: 53%

Retreat of the Western Cordilleran Ice Sheet Margin During the Last Deglaciation

Darvill

Menounos

Goehring

et al. 2018

Geophysical Research Letters

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“…We interpret this unit as being deposited soon after glaciers retreated from their Last Glacial Maximum (LGM) position, likely between 17 and 14 ka (Kopczynski et al, 2017;Mann & Peteet, 1994;Misarti et al, 2012). Above the base, the unit features moderate-amplitude parallel reflectors and ranges from 25 to 50 m thick.…”

Section: Methods and Datamentioning

confidence: 92%

Tsunamigenic Splay Faults Imply a Long‐Term Asperity in Southern Prince William Sound, Alaska

Liberty

Haeussler

2019

Geophysical Research Letters

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Coseismic slip partitioning and uplift over multiple earthquake cycles is critical to understanding upper‐plate fault development. Bathymetric and seismic reflection data from the 1964 Mw9.2 Great Alaska earthquake rupture area reveal sea floor scarps along the tsunamigenic Patton Bay/Cape Cleare/Middleton Island fault system. The faults splay from a megathrust where duplexing and underplating produced rapid exhumation. Trenchward of the duplex region, the faults produce a complex deformation pattern from oblique, south‐directed shortening at the Yakutat‐Pacific plate boundary. Spatial and temporal fault patterns suggest that Holocene megathrust earthquakes had similar relative motions and thus similar tsunami sources as in 1964. Tsunamis during future earthquakes will likely produce similar run‐up patterns and travel times. Splay fault surface expressions thus relate to plate boundary conditions, indicating millennial‐scale persistence of this asperity. We suggest structure of the subducted slab directly influences splay fault and tsunami generation landward of the frontal subduction zone prism.

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“…As Yesner (1980) and others have discussed (Simenstad et al 1978;Laughlin 1980;Yesner 1987Yesner , 1988Siegel-Causey et al 1991;Maschner 1998;Savinetsky et al 2004), the remains of mammals, birds and fish found in North Pacific archaeological sites are not only a good measure of relative abundance at the time of harvesting but also provide a measure of change Grey fill represents periods with significant changes in air temperature which correlates with sea surface temperatures, storminess, and ocean circulation, conditions that drive ocean productivity (Misarti et al 2009). Data were reconstructed from various climatic proxies for the North Pacific, Gulf of Alaska, and greater Bering Sea region (Huesser et al 1985;Mann and Hamilton 1995;Mason et al 1995;Budd et al 1998;Mann et al 1998;Calkin et al 2001;Hu et al 2001;Mann 2001;Finney et al 2002;Jordan and Krumhardt 2003;Magny and Haas 2004;D'Arrigo et al 2005;Loso et al 2006;Misarti 2007;Misarti et al 2009Misarti et al , 2012. Adapted with modification from Maschner et al (2009a).…”

Section: Population Trends: Long Termmentioning

confidence: 99%

The decline of Steller sea lions (Eumetopias jubatus) in the North Pacific: insights from indigenous people, ethnohistoric records and archaeological data

et al. 2013

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A number of hypotheses have been proposed to explain the most recent decline (1977–2012) of Steller sea lions (SSL; Eumetopias jubatus) in the Gulf of Alaska and Aleutian Islands. We examined hypotheses about fisheries competition, environmental change, predation, anthropogenic effects and disease using observations of modern Aleut and archaeological, ethnohistoric and ethnographic data from the western Gulf of Alaska and Aleutian Islands. These data indicate that Steller sea lion numbers have declined and recovered repeatedly over the past 4500 years and were last at critically low numbers during the 1870s–1930s. Steller sea lions appear to have been more abundant during the cool periods – and lower during the warmer periods. Observations by local peoples, explorers, early government surveyors and biologists since the late 1800s suggest that low populations of SSL have been associated with high populations of Gadidae fishes (Pacific cod – Gadus macrocephalus and walleye pollock – Theragra chalcogramma) and are consistent with the ocean climate hypothesis to explain the decline of sea lions. They suggest that removals by people and killer whales (Orcinus orca) did not cause the sea lion declines, but could have compounded the magnitude of the decline as sea lion numbers approached low densities. Archaeological, anthropological and ethnohistorical analyses demonstrate that fluctuations have occurred in the North Pacific over hundreds to thousands of years and provide context for understanding the changes that occur today and the changes that will continue to occur in the future.

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Early retreat of the Alaska Peninsula Glacier Complex and the implications for coastal migrations of First Americans

Cited by 63 publications

References 31 publications

Retreat of the Western Cordilleran Ice Sheet Margin During the Last Deglaciation

Retreat of the Western Cordilleran Ice Sheet Margin During the Last Deglaciation

Tsunamigenic Splay Faults Imply a Long‐Term Asperity in Southern Prince William Sound, Alaska

The decline of Steller sea lions (Eumetopias jubatus) in the North Pacific: insights from indigenous people, ethnohistoric records and archaeological data

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