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USGS Coastal and Marine Geology Program

Field Activity Details for field activity K104PS

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AKA: none

Other ID: K-1-04-PS

Status: Completed

Organization(s): USGS, Pacific Coastal and Marine Science Center

Funding Program(s): Coastal Habitats in Puget Sound (ZP00AZZ)

Principal Investigator(s): Eric Grossman

Affiliate Investigator(s):

Information Specialist(s): Bill Danforth, Eric Grossman, Andy Stevenson

Data Type(s): Electro-Magnetic: Ground Penetrating Radar, Imagery: Photo, Imagery: Video, Location-Elevation: Navigation, Sampling: Geology, Sonar: Sidescan, Sonar: Single Beam

Scientific Purpose/Goals: Submetrix swath sonar work, ship-towed video, ground penetrating radar, coring, and sediment and eelgrass grab samples.


Start Port/Location: Seattle

End Port/Location: Pt. Angeles

Start Date: 2004-03-06

End Date: 2004-03-07

Equipment Used: underwatertelevision, sidescansonar, groundpenetratingradar, vibratingcore, VanVeengrab, imagery, GPS, augercore, bathymetry

Information to be Derived: Bathymetry and substrate type (backscatter) of Skagit Bay Shallow stratigraphy and facies (

Summary of Activity and Data Gathered: Bathymetry data along delta front shows evidence that sediment is accumulating and burying eelgrass habitats. Ship tow video reveals that extensive areas previously colonized by eelgrass (in aerial photographs of 1990 and 2000) are now covered by fine sand and silt. GPR data image the distribution and morphology of tidal and distributary channels now buried beneath agricultural land. Sediments from cores show 1-3 m of recent fine marsh sediments and peats overlying more than 3-7 m of medium to coarse sands interpreted as past tide flats. Calibrated 14C ages of wood and shells more than 10 m below the marsh surface across more than 1 km2 area of the Southern Skagit Delta range 150 to 400 yr BP signifying rapid rates of vertical accumulation (2.3 to 6.3 cm/yr) over the historical period. Preliminary analyses of surface sediments show that eelgrass biomarkers may be preserved in the recent geological record and may serve as a proxy for past eelgrass abundance.

Staff: Michael Boyle, Larry Kooker

Affiliate Staff:
Greg Hood (Skagit River System Cooperative) - Scientist
Jesse Stark (NOAA) - Captain

Notes: files exist on /imgarc2/K-1-04-PS/

Staff information imported from InfoBank
Eric Grossman (USGS Western Region) - Chief Scientist
Mike Boyle (USGS Western Region) - Mechanical Engineer
Larry Kooker (USGS Western Region) - Electronic Engineer
Andy Stevenson (USGS Western Region) - Information Specialist
Bill Danforth (USGS Woods Hole) - Information Specialist
Greg Hood (Skagit River System Cooperative) - Scientist
Jesse Stark (NOAA) - Captain



North: 48.41931 South: 48.26192 West: -122.597 East: -122.48172




Grossman, E.E., Dartnell, P., and Finlayson, D.P., 2018, High-resolution bathymetry and acoustic-backscatter data collected in 2004, 2005, 2007, and 2010 in Skagit Bay, Washington: U.S. Geological Survey data release.


Data Acquired

Survey EquipmentSurvey InfoData Type(s)Data Collected
underwatertelevision --- Video
sidescansonar --- Sidescan
groundpenetratingradar --- Ground Penetrating Radar
vibratingcore --- Geology
Station Information
VanVeengrab --- Geology
Station Information
imagery --- Photo
Station Information
GPS --- Navigation
Best file with nav in ArcInfo E00 format
Global positioning system (GPS) data k-1-04-ps.060 (Provisional best file)
Global positioning system (GPS) data k-1-04-ps.061 (Provisional best file)
augercore --- Geology
Station Information
bathymetry --- Single Beam
File list

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