Physiographic Zones of the Sea Floor offshore of western and southern Martha's Vineyard and north of Nantucket, Massachusetts

Sea floor physiographic zones were qualitatively defined in ArcGIS, following the criteria defined by Kelley and others (1996), primarily on the basis of acoustic backscatter, bathymetrically derived slope and roughness, surficial geologic interpretations from seismic-reflection data, and textural information from bottom photographs and sediment samples. The interpretation was initiated by creating a new polygon feature class in an ArcMap 10.5 file geodatabase based on the extent of the regional bathymetric DEM (Andrews and others, 2018, and clipped to the extent of this study area). New fields called 'Confidence' and 'PhysioZo_1' were created in the attribute table. The polygon was then partitioned into multiple physiographic zone polygons using 'cut polygon' and 'auto-complete polygon' in an edit session. As each new polygon area was created, the 'PhysioZo_1' attribute field was populated with the appropriate physiographic zone label. In general, polygon editing was done at scales between 1:8,000 and 1:25,000, depending on the size of the interpreted zone and the resolution of the source data.

The polygon feature class containing the physiographic zone units was assigned topology rules, (i.e. no gaps and no overlaps). Topology errors were identified and remedied using the topology toolbar in ArcMap (10.5). Finally, the physiographic zones were exported from the geodatabase as a shapefile

The physiographic zone polygon feature class was exported to a shapefile and the 'Shape_Area' and 'Shape_Length' fields were deleted from its attribute table (ArcCatalog and ArcMap 9.3.1). Finally, the shapefile was reprojected from UTM zone 19 N, WGS84 to GCS WGS84 using ArcToolbox > Data Management Tools > Projections and Transformations > Feature > Project.

Added keywords section with USGS persistent identifier as theme keyword.