Interpretation of Sedimentary Environments from National Oceanic and Atmospheric Administration (NOAA) Survey H12298 in Block Island Sound (Geographic, WGS 84, H12298SEDENV.SHP)

The GeoTIFF images of the multibeam and sidescan-sonar data from survey H12298 and the point data layers from bottom photography and grain-size analyses of sediments collected from this survey area were imported into the ArcMap 9.3.1. Bottom features were interpreted based on the bathymetry, sidescan, bottom photography, and textural analyses. The individually interpreted features (i.e. boulders) were outlined using the available graphic tools. This and all subsequent process steps were completed by the same person, Katherine McMullen.

Sedimentary environments were interpreted largely based on the sea floor interpretations, although some polygons have different borders to reflect overlap or other features. The h12298interp.shp file was copied and renamed in ArcCatalog 9.3.1 and polygon labels were changed to reflect sedimentary environments. Boulders, cobbles, and glaciolacustrine sediments indicate environments of erosion or nondeposition in this study area, sand waves indicate coarse-grained bedload transport, and the remaining modern marine sediments are likely environments characterized by sorting and reworking. In areas where the interpretation polygons overlapped, the dominant feature on the sea floor was used. Polygons with overlap were intersected, clipped, and either merged with the dominant area or relabeled using the tools in ArcMap 9.3.1.
In outlining the borders of the sedimentary environments in the H12298 area, we attempted to match those in adjacent study areas (USGS Open-File Reports 2007-1012, 2012-1005, and 2014-1160). The interpretations in OFR 2012-1005 were done using 4-m bathymetry, so some features visible in the 2-m bathymetry of overlapping and adjacent areas in this survey were not discernable. Likewise, features that overlap two adjoining surveys are often difficult to outline when the data from only one survey is available. Thus, the sedimentary environments have some minor discrepancies with adjoining study areas.

Edits to the metadata were made to fix any errors that MP v 2.9.36 flagged. This is necessary to enable the metadata to be successfully harvested for various data catalogs. In some cases, this meant adding text "Information unavailable" or "Information unavailable from original metadata" for those required fields that were left blank. Other minor edits were probably performed (title, publisher, publication place, etc.). Attempted to modify http to https where appropriate. The source information was incomplete and had to be modified to meet the standard. Updated the link to the field activity. The metadata date (but not the metadata creator) was edited to reflect the date of these changes. The metadata available from a harvester may supersede metadata bundled within a download file. Compare the metadata dates to determine which metadata file is most recent.

Added keywords section with USGS persistent identifier as theme keyword.