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Geoarchaeology of the Nehalem spit: Redistribution of beeswax galleon wreck debris by Cascadia earthquake and tsunami (∼A.D. 1700), Oregon, USA
Author(s) -
Peterson Curt D.,
Williams Scott S.,
Cruikshank Kenneth M.,
Dubè John R.
Publication year - 2011
Publication title -
geoarchaeology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.696
H-Index - 44
eISSN - 1520-6548
pISSN - 0883-6353
DOI - 10.1002/gea.20349
Subject(s) - geology , debris , foredune , fault scarp , geoarchaeology , progradation , geomorphology , subduction , oceanography , seismology , archaeology , shore , paleontology , tectonics , structural basin , geography , facies
A coincidence of the Beeswax galleon shipwreck (ca. A.D. 1650–1700) and the last Cascadia earthquake tsunami and coastal subsidence at ∼A.D. 1700 redistributed and buried wreck artifacts on the Nehalem Bay spit, Oregon, USA. Ground‐penetrating radar profiles (∼7 km total distance), sand auger probes, trenches, cutbank exposures (29 in number), and surface cobble counts (49 sites) were collected from the Nehalem spit (∼5 km 2 area). The field data demonstrate (1) the latest prehistoric integrity of the spit, (2) tsunami spit overtopping, and (3) coseismic beach retreat since the A.D. 1700 great earthquake in the Cascadia subduction zone. Wreck debris was (1) initially scattered along the spit ocean beaches, (2) washed over the spit by nearfield tsunami (6–8 m elevation), and (3) remobilized in beach strandlines by catastrophic beach retreat. Historic recovery of the spit (150 m beach progradation) and modern foredune accretion (>5 m depth) have buried both the retreat scarp strandlines and associated wreck artifacts. The recent onshore sand transport might re‐expose heavy ship remains in the offshore area if the wreck grounded in shallow water (<20 m water depth of closure). © 2011 Wiley Periodicals, Inc.