Location and analyses of sediment samples collected on Stellwagen Bank during U.S. Geological Survey field activity 2017-044-FA, aboard the R/V Auk, September 12-14, 2017

Sediment sampling methods:
As a part of the process of mapping the sea floor, the USGS developed the SEABed Observation and Sampling System (SEABOSS) to collect samples and video and photographic images of the seabed to aid in the interpretation of seabed sonar imagery. A modified Van Veen sediment grab sampler is mounted in the center of the SEABOSS frame, which ensures the sampler is properly oriented on the seabed when a sample is collected. Before deployment, the sampler bucket's jaws are opened by collapsing the extended arms to a near-horizontal position and locking them in place with two catches. The sampler operates passively to sample the seabed; it is not spring loaded.
To collect a sediment sample, the SEABOSS frame was lowered gently onto the seabed, reducing tension on the cable, which caused the two locking catches to be automatically released by gravity. As the cable was retrieved, the grab sampler's arms were pulled upward, closing the bucket around the sediment, and the SEABOSS was lifted off the seabed.
The SEABOSS was retrieved and set upon a wooden platform that kept the sampler bucket and camera systems above the deck. The sampler's arms were held in the upright position manually or by tension on the cable, the two doors on the upper side of the bucket were opened, and the sediment was removed. For this project, the upper 2 cm of sediment, representing the surface of the seabed, were removed with a rectangular shovel 2-cm deep and stored in a plastic bag for grain-size analysis. The remaining sediment was dumped into a tray on the deck below the sampler and discarded, after which the sampler was washed in preparation for sampling at the next site. Further information on the SEABOSS can be found in Valentine and others (2000).

Samples were analyzed in the sediment laboratory at the USGS Woods Hole Coastal and Marine Science Center. Coarse fraction determined by sieve; fine fraction determined by Coulter Counter. Additionally carbonate concentrations were determined through acid wash analysis on the coarse fraction. See Poppe and others (2014) for analytical specifics for both grain size and carbonate measurement processes. Sediment statistics were recorded in MS Excel file (XLS) and returned to the scientist.

The Excel spreadsheet was exported as an MS-DOS CSV file using Excel 2016.

Using ArcGIS 10.6.1, the CSV file was converted to a shapefile within ArcMap using File - Add Data - Add XY data. The CSV file was selected, with the x-coordinate set to LONGITUDE and the y-coordinate set to LATITUDE. The coordinate system of the input coordinates was set to the geographic coordinate system GCS_WGS_1984. Once the event theme was added to ArcMap, the data were then converted to a shapefile by right-clicking on the event theme - Data - Export Data. All of the features were exported using the layer's source data for the coordinate system. The output shapefile was set to 2017-044-FA_sedsamps.shp.

Added keywords section with USGS persistent identifier as theme keyword.