Late Pleistocene mountain glaciation in Alaska: Key chronologies

Jason P. Briner, Darrell S Kaufman

Research output: Contribution to journalArticle

53 Citations (Scopus)

Abstract

Moraine sequences of mountain glaciers can be used to infer spatial and temporal patterns of climate change across the globe. Alaska is an accessible high-latitude location in the Northern Hemisphere and contains a rich record of alpine glaciation. Here, we highlight the key chronologies from three mountain ranges in Alaska that reveal the timing and spatial extent of Late Pleistocene glaciation, and pay particular attention to age of the penultimate glaciation. The most extensive glacier advance of the last glaciation occurred prior to the last global glacial maximum. Cosmogenic exposure ages from moraine boulders in three sites spanning 800 km indicate that this penultimate advance most likely culminated during marine isotope stage (MIS) 4 or early MIS 3. During MIS 2, more limited glacier expansion generated multiple moraines that span from prior to the global Last Glacial Maximum (LGM) through the Lateglacial period. Glaciers retreated from their terminal positions ca. 27-25 ka in arctic Alaska and ca. 22-19 ka in southern Alaska. Moraines in at least two ranges date to 12-11 ka, indicating a glacial advance during the Younger Dryas period. Reconstructed equilibrium-line altitudes of both penultimate and MIS 2 glaciers were lowered only 300-600m - much less than elsewhere in the Americas. Alaska is documented to have been more arid during MIS 2, perhaps due in large part to the exposure of the Bering-Chukchi platform during eustatic sea-level lowering. The restricted ice extent is also consistent with the output of climate models that simulate a lack of significant summer cooling.

Original languageEnglish (US)
Pages (from-to)659-670
Number of pages12
JournalJournal of Quaternary Science
Volume23
Issue number6-7
DOIs
StatePublished - Sep 2008

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marine isotope stage
glaciation
chronology
Pleistocene
glacier
mountain
moraine
glacier advance
equilibrium line
last glaciation
Younger Dryas
Last Glacial Maximum
climate modeling
Northern Hemisphere
Mountains
Isotopes
Glacier
Late Pleistocene
Chronology
sea level

Keywords

  • Alaska
  • Chronology
  • Glaciation
  • Late Pleistocene
  • Mountain glacier

ASJC Scopus subject areas

  • Earth and Planetary Sciences (miscellaneous)
  • Palaeontology

Cite this

Late Pleistocene mountain glaciation in Alaska : Key chronologies. / Briner, Jason P.; Kaufman, Darrell S.

In: Journal of Quaternary Science, Vol. 23, No. 6-7, 09.2008, p. 659-670.

Research output: Contribution to journalArticle

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