identifier
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Wiley Slough

USGS Topo Sheet: Utsalady

Geographic coordinates: 48°19.52' N, 122°22.63' W

Paleoseismic record: Based on very limited reconnaissance, this site is unlikely to have preserved a record of recognizable paleoseismic events.

Setting: This site is on the edge of a large area of diked lowland at the south edge of the Skagit delta on Fir Island. Cores and cuts were examined near the Washington State Wildlife Area office and boat launch.

Stratigraphic description: Eight cores (2.5-cm-diameter) in former marshes that apparently developed in old river channels showed 20-80 cm of gray peaty mud over 40-60 cm of sand and silty sand. River eroded cuts along the west bank of Wiley Slough at the boat launch show massive to planar-bedded silt and fine sand with detrital organics.

Paleontology/Paleoecology: No paleontologic work has been completed.

Geologic interpretation: This site is in a complex delta environment characterized by migrating river channels with rapid erosion and deposition during river floods. Most of the area is diked and fringing marshes seaward of dikes may have developed since the dikes were built. Lithologic changes in cores produced by coseismic land-level changes and tsunamis would be difficult to distinguish from changes produced by floods and storms, especially under drained and cultivated land. However, paleoliquefaction features might be found in exposures along river channels and canals in this area.

Date of last work at site: September 1997

Status of work: No additional work is planned.

Published information on this site: None

Investigators: A. Nelson

Please use the following format in citing information from this page:

Nelson, A.R., Wiley Slough, in Bucknam, R.C., compiler, 1999, Atlas of reconnaissance data from paleoseismic studies in the Puget Sound region, Washington: U.S. Geological Survey Web Page, http://earthquake.usgs.gov/regional/pacnw/paleo/atlas.html.

This URL is: http://earthquake.usgs.gov/regional/pacnw/paleo/reports/wileyslo.htm
Modified April 19, 2004 by Susan Rhea