Tracklines of a multibeam survey of the Hudson Shelf Valley carried out in 1996 (polyline shapefile, geographic, WGS 84)

The Hudson Shelf Valley is the submerged seaward extension of the ancestral Hudson River drainage system and is the largest physiographic feature on the Middle Atlantic continental shelf. The valley begins offshore of New York and New Jersey at about 30-meter (m) water depth, runs southerly and then southeasterly across the Continental Shelf, and terminates on the outer shelf at about 85-m water depth landward of the head of the Hudson Canyon. Portions of the 150-kilometer-long valley were surveyed in 1996, 1998, and 2000 using a Simrad EM1000 multibeam echosounder mounted on the Canadian Coast Guard ship Frederick G. Creed. The purpose of the multibeam echosounder surveys was to map the bathymetry and backscatter intensity of the sea floor of the valley, providing a framework for geologic, oceanographic, and geochemical studies. The data from the three surveys are combined to produce grids of bathymetry and backscatter intensity at 12-m resolution that cover the entire valley and the head of the Hudson Canyon. The mapping was done by the U.S. Geological Survey in cooperation with the U.S. Army Corps of Engineers with support from the Canadian Hydrographic Service and the University of New Brunswick.