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Cited by 106Geology and Paleoclimatology ResearchCryospheric studies and observationsGeological formations and processes

The DOI matches its Crossref record; 93 of the 93 references it cites were found in a registry or an index; none of the 77 sources its claims cite is checked for support yet.

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

Open access
Darvill, C. M., Menounos, B., Goehring, B. M., Lian, O. B., Caffee, M. W.·2018·Geophysical Research Letters
DOI 10.1029/2018gl079419
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Abstract

The timing of Cordilleran Ice Sheet deglaciation along the central coast of British Columbia, Canada, informs climate forcing and early human migration. Thirty-two 10Be 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.

Overview

AI snapshot

Written from the paper’s full text.

TL;DR

New 10Be exposure ages from the central coast of British Columbia show the western margin of the Cordilleran Ice Sheet was retreating by 18.1 ± 0.2 ka, earlier than some ice-sheet simulations and prior to maximum extents of other sectors. The data indicate diachronous deglaciation and imply ice-free coastal areas existed by at least 18.1 ka, with a low-altitude site exposed by 17.7 ± 0.3 ka.

Key findings

  • The western Cordilleran Ice Sheet margin was retreating by 18.1 ± 0.2 ka (n = 5) and a low-altitude site was exposed by at least 17.7 ± 0.3 ka (n = 4).
  • Parts of the southern margin reached a maximum at ca. 17.6–16.6 ka, while the western margin had already retreated, demonstrating a diachronous response during deglaciation.
  • A moraine on Mt. Buxton yielded 16.6 ± 0.5 ka (n = 5), and nearby Hunter Island erratics yielded 16.8 ± 0.5 ka (n = 5), consistent with an advance or still-stand around 17–16 ka.
  • Later exposure ages include Hecate Island at 14.2 ± 0.5 ka (n = 4 after excluding two bedrock outliers), King Island at 14.5 ± 0.7 ka (n = 4), and Rivers Inlet at 13.8 ± 0.1 ka (n = 3), indicating ice thinning and retreat into fjords.

Methods

  • The authors sampled 32 boulders and bedrock surfaces for cosmogenic 10Be exposure dating from seven locations on the western Canadian coast: moraine boulders (n = 8), erratic boulders (n = 15), and glacially smoothed bedrock (n = 9).
  • Samples were collected above the established marine limit and not corrected for glacioisostatic adjustment; 10Be/9Be ratios were measured at PRIME Lab, and ages calculated with CRONUScalc using a combined production rate of 3.92 atoms g−1 a−1 and the “Sf” scaling scheme.
  • Ages are presented as minimum exposure ages with internal analytical errors and as site groups using medians and interquartile ranges.

Limitations

  • The paper states that ages were not corrected for surface erosion, snow cover, or glacio-isostatic adjustment, so they represent minimum exposure ages.
  • The authors exclude two Hecate Island bedrock ages as outliers, likely due to nuclide inheritance from insufficient subglacial erosion, and note that a bedrock knoll may have shielded those samples.
  • The text states that postglacial sea-level change west of Calvert Island before 16 ka remains uncertain; more generally, the study’s small per-site sample sizes and reliance on minimum ages are evident from the presented data.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1029/2018gl079419

Cites

93 of 93 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Verification

Claims the paper makes

0 of 77 cited sources checked · 0 supported · 0 flagged

  • Findingown data

    A low-altitude site on the western margin was exposed by at least 17.7 ± 0.3 ka.

    “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.”
    Quote in the paperSubstantial claim
  • Findingown data

    The western margin of the Cordilleran Ice Sheet along the central coast of British Columbia was retreating by 18.1 ± 0.2 ka.

    “These data show the western ice margin was retreating by 18.1 ± 0.2 ka, consistent with the global record of ice mass loss.”
    • Also stated in: § 5.1. Diachronous Marginal Retreat · hedged
      “Our 10 Be dating chronology reveals that the western margin of the Cordilleran Ice Sheet along the central coast of British Columbia retreated to the present-day coastline by at least 18.1 ± 0.2 ka; earlier than simulated by ice sheet models (Seguinot et al., 2016).”
    • Also stated in: § 10.1029/2018GL079419 · boosted
      “Our study shows that retreat of the western margin of the Cordilleran Ice Sheet during the last deglaciation occurred earlier than previously thought, by at least 18.1 ka and prior to the maxima of other parts of the ice sheet.”
    Quote in the paperSubstantial claim
  • Findingown data

    The Hecate Island exposure ages are similar to samples from King Island exposed by thinning ice at 14.5 ± 0.7 ka (n = 4).

    “The Hecate Island ages are similar to samples exposed by thinning ice at 14.5 ± 0.7 ka (n = 4) and 13.8 ± 0.1 ka (n = 3) from King Island and Rivers Inlet, respectively (Figures 3.6 and 3.7).”
    Quote in the paperNot a substantial claim
  • Findingown data

    King Island was exposed by ice thinning into fjords at 14.5 ± 0.7 ka.

    “At a similar time, two other sites were exposed by ice thinning into fjords below: 14.5 ± 0.7 ka for King Island and 13.8 ± 0.1 ka for Rivers Inlet (Figures 2 and 3).”
    Quote in the paperSubstantial claim
  • Findingown data

    The Hecate Island exposure ages are similar to samples from Rivers Inlet exposed by thinning ice at 13.8 ± 0.1 ka (n = 3).

    “The Hecate Island ages are similar to samples exposed by thinning ice at 14.5 ± 0.7 ka (n = 4) and 13.8 ± 0.1 ka (n = 3) from King Island and Rivers Inlet, respectively (Figures 3.6 and 3.7).”
    Quote in the paperNot a substantial claim
  • It may state two separate claims as one. 16
  • Probably not a substantial claim. 8

  • It may state two separate claims as one.

    Findingown data

    There is high internal consistency within the 10Be data set, with low interquartile ranges for each site and median ages between sites consistent with ice retreating and thinning north and eastward.

    “There is high internal consistency within the data set, with low interquartile ranges for each site and median ages between sites that are consistent with ice retreating and thinning north and eastward.”
    Quote in the paperSubstantial claim

  • It may state two separate claims as one.

    Findingcitation

    A moraine deposited at 16.6 ± 0.5 ka on the western flank of Mt. Buxton on Calvert Island accords with the well-dated maximum of the Puget Lobe ca. 17.6-16.6 ka and exposure ages from the northern, western, and southern margins of the ice sheet.

    “On Calvert Island, a moraine deposited at 16.6 ± 0.5 ka on the western flank of Mt.Buxton accords with the well-dated maximum of the Puget Lobe ca.17.6-16.6ka (Porter & Swanson, 1998) and exposure ages from the northern, western, and southern margins of the ice sheet.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Porter & Swanson, 1998 source

  • It may state two separate claims as one.

    Findingown data

    Between 16.6 and 14.2 ka, net retreat of the western ice sheet margin was only 10-km northward of Mt. Buxton, but it thinned markedly.

    “Between 16.6 and 14.2 ka, net retreat of the western ice sheet margin was only 10-km northward of Mt.Buxton, but it thinned markedly.”
    Quote in the paperSubstantial claim

  • It may state two separate claims as one.

    Findingcitation

    Hecate Island was exposed at 14.2 ± 0.5 ka, likely during retreat following a readvance of the ice sheet.

    “Hecate Island was exposed at 14.2 ± 0.5 ka, likely during retreat following a readvance of the ice sheet given the similarity between our exposure ages and radiocarbon ages for a readvance on Calvert Island (Eamer et al., 2017).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Eamer et al., 2017

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • It may state two separate claims as one.

    Findingown data

    Removal of the two Hecate Island bedrock samples results in a small change in the median age (from 14.8 to 14.2 ka) but a large change in the interquartile range (from ±3.1 to ±0.5 ka).

    “The removal of these two bedrock samples results in a small change in the median age (from 14.8 to 14.2 ka) but a large change in the interquartile range (from ±3.1 to ±0.5 ka).”
    Quote in the paperSubstantial claim

  • It may state two separate claims as one.

    Premisecitation

    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.

    “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, 2002a;Blaise et al., 1990;Davies et al., 2011;Luternauer, Clague, et al., 1989;Luternauer, Conway, et al., 1989).”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites Barrie & Conway, 1999 source
    • cites Blaise et al., 1990 source
    • cites Davies et al., 2011 source

  • Probably not a substantial claim.

    Premisecitation

    The central coast of British Columbia represents a key location in the proposed coastal route for the first human migration into the Americas.

    “This region represents a key location in the proposed coastal route for the first human migration into the Americas (Mann & Peteet, 1994;B. A. Potter et al., 2017B. A. Potter et al., , 2018)).”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites Mann & Peteet, 1994 source
    • cites B. A. Potter et al., 2017

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites B. A. Potter et al., 2018

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim. The paper’s conclusions may not depend on it. The paper may give no reason why it holds.

    Interpretationreasoning

    The early retreat of the western ice margin exposed numerous islands that could have been used by early people migrating southward.

    “The early retreat of the western ice margin exposed numerous islands that could have been used by early people migrating southward.”
    Quote in the paperNot a substantial claim

  • It may state two separate claims as one.

    Premisecitation

    Maximum and minimum limiting radiocarbon ages from Vancouver Island demonstrate that ice advanced over the island after 19.6 ka and retreated before 15.7 ka.

    “Maximum and minimum limiting radiocarbon ages from Vancouver Island (Al-Suwaidi et al., 2006) demonstrate that ice advanced over the island after 19.6 ka and retreated before 15.7 ka.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Al-Suwaidi et al., 2006 source

  • Probably not a substantial claim.

    Premisenone given

    The time at which the ice margin left the continental shelf along the central coast of British Columbia remains uncertain.

    “However, the time at which the ice margin left the continental shelf along the central coast of British Columbia (Figure 1) remains uncertain.”
    Quote in the paperSubstantial claim

  • It may state two separate claims as one.

    Study design and conductown data

    Two ages from glacially smoothed bedrock samples on Hecate Island were excluded because they fall well outside the upper bounds of the interquartile range and do not overlap, within 1σ analytical errors, with any other samples from Hecate Island.

    “However, we exclude two ages obtained from glacially smoothed bedrock samples on Hecate Island since they fall well outside the upper bounds of the interquartile range and do not overlap, within 1σ analytical errors, with any other samples from Hecate Island.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim. The paper’s conclusions may not depend on it.

    Premisecitation

    Genetic data suggest that the first human migration south of the Cordilleran Ice Sheet may have occurred after ca. 16.0 ka.

    “Genetic data suggest that the first human migration south of the Cordilleran Ice Sheet may have occurred after ca.16.0 ka (Llamas et al., 2016;Moreno-Mayar et al., 2018;Raghavan et al., 2015;Skoglund & Reich, 2016), but the route taken around the continental ice sheets remains unclear (Potter et al., 2017(Potter et al., , 2018)).”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites Llamas et al., 2016 source
    • cites Moreno-Mayar et al., 2018 source
    • cites Raghavan et al., 2015 source

  • It may state two separate claims as one.

    Interpretationcitation

    This finding is consistent with a trend of ice sheet thinning by around 14.0 ka, during which the Cordilleran Ice Sheet contributed 2.5-3.0 m to eustatic sea-level rise.

    “This finding is consistent with a trend of ice sheet thinning by around 14.0 ka, during which the Cordilleran Ice Sheet contributed 2.5-3.0 m to eustatic sea-level rise (Lambeck et al., 2014;Margold et al., 2014;Menounos et al., 2017), potentially contributing to meltwater pulses at this time (Gomez et al., 2015;Gregoire et al., 2016Gregoire et al., , 2012;;Ivanovic et al., 2017).”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites Lambeck et al., 2014 source
    • cites Margold et al., 2014 source
    • cites Menounos et al., 2017 source

  • Probably not a substantial claim. The paper’s conclusions may not depend on it.

    Study design and conductown data

    Using the median and interquartile ranges yields similar results to the weighted mean and standard error calculated to include uncertainty on the production rate.

    “Using the median and interquartile ranges yields similar results to the weighted mean and standard error calculated to include uncertainty on the production rate (supporting information Table S1).”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim. The paper’s conclusions may not depend on it.

    Study design and conductnone given

    Two bedrock exposure ages from Hecate Island were excluded from the analysis.

    “Note that the two bedrock ages from Hecate Island have been excluded (see main text for discussion).”
    Quote in the paperNot a substantial claim

  • It may state two separate claims as one.

    Interpretationown data

    Our new reconstruction demonstrates that at least parts of the western coastal margin were exposed by 18.1 ka, strengthening the case for a viable coastal route available to the first humans entering the Americas.

    “Our new reconstruction demonstrates that at least parts of the western coastal margin were exposed by 18.1 ka, strengthening the case for a viable coastal route available to the first humans entering the Americas.”
    Quote in the paperSubstantial claim

  • It may state two separate claims as one.

    Interpretationcitation

    The western edge of the Cordilleran Ice Sheet advanced across Hecate Strait at ca. 30.0 ka and reached Haida Gwaii after ca. 22.0 ka, but was retreating by ca. 19.4 ka.

    “The timing of deglaciation reported here agrees with findings from north of the study area (Blaise et al., 1990;Clague et al., 1982;Mathewes & Clague, 2017;Warner et al., 1982), implying that the western edge of the Cordilleran Ice Sheet advanced across Hecate Strait at ca. 30.0 ka and reached Haida Gwaii after ca.22.0 ka, but was retreating by ca.19.4 ka (Figure 4i).”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites Blaise et al., 1990 source
    • cites Clague et al., 1982 source
    • cites Mathewes & Clague, 2017 source

  • Probably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.

    Premisecitation

    The regional signature of ocean temperatures in the Northeast Pacific during deglaciation has been linked to the strength of the California Current driven by movement of the Intertropical Convergence Zone, in turn linked to the growth and decay of the Laurentide and Cordilleran ice sheets.

    “The regional signature of ocean temperatures in the Northeast Pacific during deglaciation has been linked to the strength of the California Current driven by movement of the Intertropical Convergence Zone, in turn linked to the growth and decay of the Laurentide and Cordilleran ice sheets (Taylor et al., 2015).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Taylor et al., 2015 source

  • It may state two separate claims as one.

    Interpretationcitation

    The pattern of ice retreat was complex, and ice remained proximal until ca. 15.0 ka, but ice-free or partially ice-free islands along the coast may have facilitated southward human migration.

    “The pattern of ice retreat was complex, and ice remained proximal until ca.15.0 ka (Davies et al., 2011;Lesnek et al., 2018;Menounos et al., 2017), but ice-free or partially ice-free islands along the coast may have facilitated southward human migration (Erlandson et al., 2011;Mandryk et al., 2001).”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites Davies et al., 2011 source
    • cites Lesnek et al., 2018

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites Menounos et al., 2017 source

  • Probably not a substantial claim.

    Study design and conductnone given

    Tandem collection of boulders and bedrock allowed assessment of resetting of nuclide concentrations by subglacial erosion.

    “Tandem collection of boulders and bedrock allowed us to assess resetting of nuclide concentrations by subglacial erosion.”
    Quote in the paperSubstantial claim

  • It may state two separate claims as one.

    Interpretationcitation

    Short-lived cooling of surface ocean temperatures in the eastern Pacific and Gulf of Alaska at 17-16 ka may have slowed the retreat of ice on the western margin and triggered the advance of the Puget Lobe to the south.

    “Short-lived cooling of surface ocean temperatures in the eastern Pacific (Figure 4d) and Gulf of Alaska (Figure 4c) at 17-16 ka may have slowed the retreat of ice on the western margin and triggered the advance of the Puget Lobe to the south (Cosma & Hendy, 2008;Davies et al., 2011;Hendy & Cosma, 2008;Maier et al., 2018;Praetorius & Mix, 2014;Praetorius et al., 2015;Taylor et al., 2014).”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites Cosma & Hendy, 2008

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites Davies et al., 2011 source
    • cites Hendy & Cosma, 2008 source

  • It may state two separate claims as one.

    Premisecitation

    The chronology and viability of the interior corridor remain contentious, but it likely became ice-free between 15.0 and 13.0 ka, and viable sometime thereafter.

    “The chronology and viability of this interior corridor remain contentious, but it likely became ice-free between 15.0 and 13.0 ka, and viable sometime thereafter (Heintzman et al., 2016;Hickin et al., 2015;Jackson et al., 1999;Munyikwa et al., 2017;Pedersen et al., 2016;B. A. Potter et al., 2017).”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites Heintzman et al., 2016

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites Hickin et al., 2015 source
    • cites Jackson et al., 1999 source

  • It may state two separate claims as one.

    Interpretationcitation

    Fossil evidence for deglacial refugia from these islands, as well as Haida Gwaii and Vancouver Island, add to the story of an early habitable coastal route, likely before an interior route became viable.

    “Fossil evidence for deglacial refugia from these islands, as well as Haida Gwaii (Mathewes et al., 2015) and Vancouver Island (Al-Suwaidi et al., 2006;Ward et al., 2003) add to the story of an early habitable coastal route, likely before an interior route became viable.”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites Mathewes et al., 2015 source
    • cites Al-Suwaidi et al., 2006 source
    • cites Ward et al., 2003 source
23 of 23

  • The paper relies on this without support.

    The western margin of the Cordilleran Ice Sheet was the only marine-terminating section of the ice sheet.

    “The western ice margin was the only marine terminating section of the Cordilleran Ice Sheet, so retreat may have been triggered by increased calving induced by eustatic sea-level rise (Figure 4a) and rapid deglacial isostatic adjustment (Clague, 1985(Clague, , 1989;;Margold et al., 2013).”
1 of 1

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

  • Retreat of the western margin of the Cordilleran Ice Sheet and associated postglacial uplift occurred early enough to have provided a migration route for people prior to the earliest known archaeological sites south of the ice sheets.

    “indicate that retreat of the western margin of the Cordilleran Ice Sheet and associated postglacial uplift occurred early enough to have provided a migration route for people prior to the earliest known archaeological sites south of the ice sheets”

    From The age of the opening of the Ice-Free Corridor and implications for the peopling of the Americas (2022) · cites this paper as [53]

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • Sea-level rise cites the insolation panel

    Minor

    The text cites Figure 4a for eustatic sea-level rise, but the caption identifies panel a as insolation and panel b as sea level.

  • Insolation cites the sea-level panel

    Minor

    The text cites Figure 4b for Northern Hemisphere summer insolation, but the caption identifies panel b as sea level and panel a as insolation.

  • Opposing ice-flow directions at Rivers Inlet

    Minor

    The study-area text describes ice flowing east along Rivers Inlet, while the Figure 2 caption describes it flowing westward from Rivers Inlet.

3 of 3

Citations

Cites

Flagged first, then by citations

Research works printed but not linked: 3

  1. 10.1139/e99‐038 · DOI
  2. Keddie G., 1979, The late ice age of southern Vancouver Island, The Midden Archaeological Society of British Columbia, 11, 16
  3. 10.5194/tcd‐9‐4147‐2015 · DOI

Cited by

Sorted by citations

Related

Metadata

Authors
Darvill, C. M., Menounos, B., Goehring, B. M., Lian, O. B., & Caffee, M. W.
Affiliations
  • University of Northern British Columbia (CA)
  • Tulane University (US)
  • University of the Fraser Valley (CA)
  • Purdue University West Lafayette (US)
Corresponding author
Darvill, C. M.
ORCID
Venue
Geophysical Research Letters
Publisher
American Geophysical Union (AGU)
Published
2018-09-26
Volume
45
Issue
18
Pages
9710-9720
ISSN
  • 0094-8276 (ISSN-L)
  • 1944-8007
DOI
10.1029/2018gl079419
OpenAlex
W2888958070
Cited by
105
References
91
Citations by year
2026: 5 · 2025: 4 · 2024: 7 · 2023: 9 · 2022: 22 · 2021: 34 · 2020: 9 · 2019: 13 · 2018: 2
FWCI
6.93
Type
journal article
Language
en
Open access
Licence
Locations
  • Geophysical Research Letters (publishedVersion, cc-by-nc-nd)
  • Research Explorer (The University of Manchester) (submittedVersion, cc-by-nc-nd)
Funders
  • Canada Foundation for Innovation
  • Natural Sciences and Engineering Research Council of Canada
Topics
  • Physical Sciences › Earth and Planetary Sciences › Atmospheric Science › Geology and Paleoclimatology Research
  • Physical Sciences › Earth and Planetary Sciences › Atmospheric Science › Cryospheric studies and observations
  • Physical Sciences › Earth and Planetary Sciences › Earth-Surface Processes › Geological formations and processes
Keywords
Cordilleran Ice Sheet, last deglaciation, 10Be exposure dating, glacial erratics, British Columbia coast, ice mass loss

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