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Constraints on regional drivers of relative sea-level change around Cordova, Alaska

Garrett, E.; Barlow, N.L.M.; Cool, H.; Kaufman, D.; Shennan, I.; Zander, P.

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E. Garrett

N.L.M. Barlow

H. Cool

D. Kaufman

I. Shennan

P. Zander


New records of paleoenvironmental change from two lakes near Cordova, south central Alaska, combined with analysis of previously reported sediment sequences from the adjacent Copper River Delta, provide quantitative constraints on a range of Earth system processes through their expression in relative sea-level change. Basal sediment ages from Upper Whitshed Lake indicate ice-free conditions by at least 14,140 – 15,040 cal yr BP. While Upper and Lower Whitshed Lakes provide only upper limits to relative sea-level change, interbedded layers of freshwater peat and intertidal silt extending more than 11 m below present sea level in Copper River Delta indicate net submergence over the last 6000 years and multiple earthquake deformation cycles. In contrast, Lower Whitshed Lake, situated just above present high tide level, records only one episode of marine sedimentation, commencing AD 1120 – 1500, that we interpret as the result of isostatic subsidence due to Little Ice Age mass accumulation of the Chugach Mountain glaciers. Lower Whitshed Lake also records isostatic uplift at the end of the Little Ice Age before the end of marine sedimentation caused by ~1.5 m coseismic uplift in the great Alaska earthquake of AD 1964. We successfully explain the records of relative sea-level change from both Copper River Delta and the Whitshed Lakes by integrating the effects of eustatic sea-level rise, glacial isostasy, earthquake deformation cycles, sediment loading, sediment compaction and late Holocene changes in glacier mass into a single model. This approach provides initial quantitative constraints on the individual contributions of these processes. Taking reasonable estimates of eustasy, post-Last Glacial Maximum and Neoglacial glacial isostatic adjustment and a simple earthquake deformation cycle, we demonstrate that sediment loading and sediment compaction are both contributors to relative sea-level rise at Copper River Delta, together producing subsidence averaging approximately 1.2 mm yr-1 over the mid to late Holocene. Further isolation basin studies have the potential to greatly improve our understanding of the individual contributions of these processes in this highly dynamic region.


Garrett, E., Barlow, N., Cool, H., Kaufman, D., Shennan, I., & Zander, P. (2015). Constraints on regional drivers of relative sea-level change around Cordova, Alaska. Quaternary Science Reviews, 113, 48-59.

Journal Article Type Article
Acceptance Date Dec 9, 2014
Publication Date Apr 1, 2015
Deposit Date Dec 9, 2014
Publicly Available Date Dec 16, 2014
Journal Quaternary Science Reviews
Print ISSN 0277-3791
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 113
Pages 48-59
Keywords Relative sea level, Little Ice Age, 1964 Alaskan earthquake, Isolation basin, Diatom.


Accepted Journal Article (7.8 Mb)

Copyright Statement
NOTICE: this is the author’s version of a work that was accepted for publication in Quaternary Science Reviews. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Quaternary Science Reviews, 113, 1 April 2015, 10.1016/j.quascirev.2014.12.002.

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