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dc.contributor.authorBarnhardt, Walter A.
dc.contributor.authorSherrod, Brian L.
dc.date.accessioned2007-05-01T19:47:46Z
dc.date.available2007-05-01T19:47:46Z
dc.date.issued2006-08-16
dc.identifier.citationSedimentology 53 (2006): 1211-1228en
dc.identifier.urihttp://hdl.handle.net/1912/1596
dc.descriptionThis paper is not subject to U.S. copyright. The definitive version was published in Sedimentology 53 (2006): 1211-1228, doi:10.1111/j.1365-3091.2006.00809.x.en
dc.description.abstractEpisodic, large-volume pulses of volcaniclastic sediment and coseismic subsidence of the coast have influenced the development of a late Holocene delta at southern Puget Sound. Multibeam bathymetry, ground-penetrating radar (GPR) and vibracores were used to investigate the morphologic and stratigraphic evolution of the Nisqually River delta. Two fluvial–deltaic facies are recognized on the basis of GPR data and sedimentary characteristics in cores, which suggest partial emplacement from sediment-rich floods that originated on Mount Rainier. Facies S consists of stacked, sheet-like deposits of andesitic sand up to 4 m thick that are continuous across the entire width of the delta. Flat-lying, highly reflective surfaces separate the sand sheets and comprise important facies boundaries. Beds of massive, pumice- and charcoal-rich sand overlie one of the buried surfaces. Organic-rich material from that surface, beneath the massive sand, yielded a radiocarbon age that is time-correlative with a series of known eruptive events that generated lahars in the upper Nisqually River valley. Facies CF consists of linear sandbodies or palaeochannels incised into facies S on the lower delta plain. Radiocarbon ages of wood fragments in the sandy channel-fill deposits also correlate in time to lahar deposits in upstream areas. Intrusive, sand-filled dikes and sills indicate liquefaction caused by post-depositional ground shaking related to earthquakes. Continued progradation of the delta into Puget Sound is currently balanced by tidal-current reworking, which redistributes sediment into large fields of ebb- and flood-oriented bedforms.en
dc.description.sponsorshipThis study was supported by the Coastal and Marine Geology Program, and the Earthquake Hazards Program of the U.S. Geological Survey.en
dc.format.mimetypeapplication/pdf
dc.language.isoen_USen
dc.publisherBlackwellen
dc.relation.urihttps://doi.org/10.1111/j.1365-3091.2006.00809.x
dc.subjectEarthquakeen
dc.subjectGround-penetrating radaren
dc.subjectMount Rainieren
dc.subjectMultibeam bathymetryen
dc.subjectPuget Sound deltaen
dc.titleEvolution of a Holocene delta driven by episodic sediment delivery and coseismic deformation, Puget Sound, Washington, USAen
dc.typeArticleen
dc.identifier.doi10.1111/j.1365-3091.2006.00809.x


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