Letter | Published:

Identification of Younger Dryas outburst flood path from Lake Agassiz to the Arctic Ocean

Nature volume 464, pages 740743 (01 April 2010) | Download Citation


The melting Laurentide Ice Sheet discharged thousands of cubic kilometres of fresh water each year into surrounding oceans, at times suppressing the Atlantic meridional overturning circulation and triggering abrupt climate change1,2,3,4. Understanding the physical mechanisms leading to events such as the Younger Dryas cold interval requires identification of the paths and timing of the freshwater discharges. Although Broecker et al. hypothesized in 1989 that an outburst from glacial Lake Agassiz triggered the Younger Dryas1, specific evidence has so far proved elusive, leading Broecker to conclude in 2006 that “our inability to identify the path taken by the flood is disconcerting”2. Here we identify the missing flood path—evident from gravels and a regional erosion surface—running through the Mackenzie River system in the Canadian Arctic Coastal Plain. Our modelling of the isostatically adjusted surface in the upstream Fort McMurray region, and a slight revision of the ice margin at this time, allows Lake Agassiz to spill into the Mackenzie drainage basin. From optically stimulated luminescence dating we have determined the approximate age of this Mackenzie River flood into the Arctic Ocean to be shortly after 13,000 years ago, near the start of the Younger Dryas. We attribute to this flood a boulder terrace near Fort McMurray with calibrated radiocarbon dates of over 11,500 years ago. A large flood into the Arctic Ocean at the start of the Younger Dryas leads us to reject the widespread view that Agassiz overflow at this time was solely eastward into the North Atlantic Ocean.

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  1. 1.

    et al. Routing of meltwater from the Laurentide Ice Sheet during the Younger Dryas cold episode. Nature 341, 318–321 (1989)

  2. 2.

    Was the Younger Dryas triggered by a flood? Science 312, 1146–1148 (2006)

  3. 3.

    , & Freshwater outburst to the oceans from glacial Lake Agassiz and their role in climate change during the last deglaciation. Quat. Sci. Rev. 21, 879–887 (2002)

  4. 4.

    , & in Mechanisms of Global Climate Change at Millennial Time Scales (eds Clark, P. U., Webb, R. S. & Keigwin, L. D.) 177–202 (American Geophysical Union, Monograph 112, 1999)

  5. 5.

    Stratigraphy and paleoenvironments of Richards Island and the eastern Beaufort Continental Shelf during the last glacial-interglacial cycle. Permafrost Periglacial Process. 20, 107–125 (2009)

  6. 6.

    & Late Pleistocene glacial and periglacial aeolian activity in the Tuktoyaktuk Coastlands, NWT, Canada. Quat. Sci. Rev. 25, 2552–2568 (2006)

  7. 7.

    , , , & in The Arctic Ocean Region. The Geology of North America Vol. L (eds Grantz, A., Johnson, L. & Sweeney, J. F.) 491–502 (Geological Society of America, 1990)

  8. 8.

    ed. Marine Science Atlas of the Beaufort Sea, Geology and Geophysics (Miscell. Rep. 40, Geological Survey Canada, 1987)

  9. 9.

    Late Quaternary sequence stratigraphy of the Mackenzie Delta. Can. J. Earth Sci. 33, 1064–1074 (1996)

  10. 10.

    , & Late glacial drainage systems along the northwestern margin of the Laurentide ice sheet. Quat. Sci. Rev. 13, 805–828 (1994)

  11. 11.

    in Quaternary Glaciations – Extent and Chronology Part II, Vol. 2b (eds Ehlers, J. & Gibbard, P. L.) 373–424 (Elsevier Science and Technology Books, 2004)

  12. 12.

    et al. Basal ice facies and supraglacial melt-out till of the Laurentide Ice Sheet, Tuktoyaktuk Coastlands, western Arctic Canada. Quat. Sci. Rev. 24, 681–708 (2005)

  13. 13.

    The Mackenzie Delta area, N.W.T. (Geog. Branch, Department of Mines Technical Surveys, Memoir 8, 1963)

  14. 14.

    & Arctic freshwater forcing of the Younger Dryas cold reversal. Nature 435, 662–665 (2005)

  15. 15.

    , , , & Alternative routing of Lake Agassiz overflow during the Younger Dryas: new dates, paleotopography, and a re-evaluation. Quat. Sci. Rev. 24, 1890–1905 (2005)

  16. 16.

    & Two possible routings for overflow from Lake Agassiz during the Younger Dryas. A Reply to Comments by T. Fisher, T. Lowell and H. Loope on “Alternative routing of Lake Agassiz overflow during the Younger Dryas: new dates, paleotopography, and a re-evaluation”. Quat. Sci. Rev. 25, 1142–1145 (2006)

  17. 17.

    , , & Stratigraphic constraints on late Pleistocene glacial erosion and deglaciation of the Chukchi margin, Arctic Ocean. Quat. Res. 67, 234–245 (2007)

  18. 18.

    & Glacial Lake Agassiz: the northwestern outlet and paleoflood. Geology 21, 9–12 (1993)

  19. 19.

    , & Preboreal oscillation caused by a glacial Lake Agassiz flood. Quat. Sci. Rev. 21, 873–878 (2002)

  20. 20.

    & Geomorphology and Quaternary history of the Mackenzie River Valley near Fort Good Hope, N.W.T., Canada. Can. J. Earth Sci. 10, 26–41 (1973)

  21. 21.

    & Cataclysmic late Pleistocene flooding from glacial Lake Missoula: a review. Quat. Sci. Rev. 4, 1–41 (1985)

  22. 22.

    , & Changes in the bathymetry and volume of glacial Lake Agassiz between 11,000 and 9300 yr B.P. Quat. Res. 54, 174–181 (2000)

  23. 23.

    & Buried Channels and Glacial-Drift Aquifers in the Fort McMurray Region, Northeast Alberta (EUB/AGS Earth Sciences Report, Alberta Geological Survey, 2007)

  24. 24.

    , & in Glacial Lake Agassiz (eds Teller, J. T. & Clayton, L.) 309–329 (Geological Association of Canada, Special Paper 26, 1985)

  25. 25.

    in Sedimentology, Geomorphology, and History of the Central Lake Agassiz Basin, Field Trip Guidebook B2 (eds Teller, J. T., Thorleifson, L. H., Matile, G. & Brisbin, W. C.) 55–94 (Geological Association of Canada Annual Meeting, 1996)

  26. 26.

    , & Evidence from the Lake Champlain Valley for a later onset of the Champlain Sea and implications for late glacial meltwater routing to the North Atlantic. Palaeogeogr. Palaeoclimatol. Palaeoecol. 246, 62–74 (2007)

  27. 27.

    et al. Geochemical proxies of North American freshwater routing during the Younger Dryas cold event. Proc. Natl Acad. Sci. USA 104, 6556–6561 (2007)

  28. 28.

    et al. Freshwater forcing of abrupt climate change during the last glaciation. Science 293, 283–287 (2001)

  29. 29.

    & Modeling the history of Lake of the Woods since 11,000 cal yr B.P. using GIS. J. Paleolimnol. 33, 483–498 (2005)

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The Mackenzie Delta research was funded by the Royal Society, the Quaternary Research Association, the British Society for Geomorphology and the Geological Survey of Canada. The Aurora Research Institute (Inuvik) and the Polar Continental Shelf Project provided logistical support. J.T.T. and Z.Y. thank the Natural Sciences and Engineering Research Council of Canada for support through the Discovery Grants Program. We thank R. A. Ashurst, P. Coles and D. K. Murton for laboratory and cartographic assistance, J. R. Mackay for drawing our attention to the Fort Good Hope region, and C. D. Clark, M. R. Frogley and E. J. Rhodes for comments. We also thank V. R. Baker and G. A. Duller for reviews that improved the manuscript considerably.

Author Contributions J.B.M. and M.D.B. designed the field research in the Mackenzie Delta region; J.B.M. and S.R.D. performed the stratigraphic analyses and interpreted the palaeogeography; M.D.B. collected samples and performed the luminescence dating; J.T.T. and Z.Y. studied and modelled the Fort McMurray region. J.B.M., J.T.T. and M.D.B. drafted the manuscript, with all authors contributing to it.

Author information


  1. Permafrost Laboratory, Department of Geography, University of Sussex, Brighton BN1 9QJ, UK

    • Julian B. Murton
  2. Sheffield Centre for International Drylands Research, Department of Geography, Winter Street, University of Sheffield, Sheffield S10 2TN, UK

    • Mark D. Bateman
  3. Geological Survey of Canada, 9860 West Saanich Road, Sidney, British Columbia V8L 4B2, Canada

    • Scott R. Dallimore
  4. Department of Geological Sciences, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada

    • James T. Teller
    •  & Zhirong Yang


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Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Julian B. Murton.

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    Supplementary information

    This file contains Supplementary Figures 1-6 with legends, Supplementary Methods, Supplementary Tables 1-2, a Supplementary Discussion and Supplementary References.

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