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Triangle Cove Marsh

USGS Topo Sheet: Juniper Beach

Geographic coordinates: 48°12.42' N, 12228.45'° W

Paleoseismic record: Insufficient fieldwork has been completed to evaluate the paleoseismic potential of this site.

Setting: Triangle Cove faces is a 1.4-km-long, 0.8-km-wide bay that is almost blocked by a narrow spit extending northeast from the base of the bluffs along the east coast of Camano Island almost to Barnum Point. Most of the cove is covered with mud and sand flats. A 400-m-wide marsh has developed between the spit and the bluffs and a 100-m-wide marsh borders stream at the head of the cove. The marsh behind the spit is largely undeveloped, but it is entirely (?) diked and so the central part of the marsh may have prograded out from the edges recently. The marsh behind a low berm at the head of the cove is probably natural, but it is small and only the western part may be inundated by normal tides.

Stratigraphic description: Silty sand in two gouge cores (<0.5 m) beneath the smaller area of marsh at the head of the cove looks more like fluvial sediment than tidal sediment. The marsh behind the spit was not cored.

Paleontology/Paleoecology: No paleontologic work has been completed.

Geologic interpretation: Tidal marsh peat in the marshes around Triangle Cove is probably thin (<0.5 m), and so it is unlikely to contain much of a record of prehistoric coseismic land-level changes, tsunamis, or storms. However, reconnaissance coring of the marsh behind the spit should be completed.

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., Triangle Cove Marsh, 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/triangle.htm
Modified July 29, 2002 by Susan Rhea