Sediment sample locations

Gray shaded-relief image (or map) is used to provide a 3D representation of the floor of San Francisco Bay, or bathymetry (water depth). The land surrounding San Francisco Bay is colored to also provide a 3D representation of relief, or topography (land elevation). Locations of USGS sediment samples collected in winter 2008 within the San Francisco Bay study area are shown as dots on the shaded-relief map, and these samples are used to verify, or groundtruth, the bathymetric map.