Polygons of global undersea features for geographic searches

A shapefile of 311 undersea features from all major oceans and seas has been created as an aid for retrieving georeferenced information resources. Version 1.1 of the data set also includes a linked data representation of 299 of these features and their spatial extents. The geographic extent of the data set is 0 degrees E to 0 degrees W longitude and 75 degrees S to 90 degrees N latitude. Many of the undersea features (UF) in the shapefile were selected from a list assembled by Weatherall and Cramer (2008) in a report from the British Oceanographic Data Centre (BODC) to the General Bathymetric Chart of the Oceans (GEBCO) Sub-Committee on Undersea Feature Names (SCUFN). Annex II of the Weatherall and Cramer report (p. 20-22) lists 183 undersea features that "may need additional points to define their shape" and includes online links to additional BODC documents providing coordinate pairs sufficient to define detailed linestrings for these features. For the first phase of the U.S. Geological Survey (USGS) project, Wingfield created polygons for 87 of the undersea features on the BODC list, using the linestrings as guides; the selected features were primarily ridges, rises, trenches, fracture zones, basins, and seamount chains. In the second phase of the USGS project, Wingfield and Hartwell created polygons for an additional 224 undersea features, mostly basins, abyssal plains, and fracture zones. Because USGS is a Federal agency, the attribute tables follow the conventions of the National Geospatial-Intelligence Agency (NGA) GEOnet Names Server (http://geonames.nga.mil/gns/html/).