Bathymetric Map of Geotechnical Corridor on U.S. Atlantic Continental Margin Southeast of Cape May: ABSTRACT

Abstract

A detailed bathymetric map was compiled of a geotechnical corridor study area on the continental margin approximately 138 km southeast of Cape May, New Jersey. Corrected narrow-beam echo soundings were collected on a 1 × 2.5-km trackline grid using loran C and satellite navigation systems. The bathymetric map is presented on six sheets of approximately 71.5 × 91.0 cm, having a total map size of 143 × 273 cm. The map covers approximately 6,246 sq km and has a scale of 1:40,000 with a 10-m contour interval. The map depicts three provinces: 1. The continental shelf has a slope of less than 1° and extends to the shelf break at the 120-m contour east of Wilmington Canyon but, on the west side of Spencer Canyon and extending eastward, the shelf break occurs at the 180-m contour. 2. The slope-rise break generally occurs at the 2,100-m contour west of Spencer Canyon, whereas the major change in gradient east of Spencer Canyon occurs at the 2,200-m contour. The continental slope has an average gradient of from 6 to 8°. The rise has an average gradient of less than 0.5 to 1°. 3. Numerous valleys dissect the slope; only Spencer Canyon extends onto the shelf, whereas many valleys originate at about 300 to 500 m water depths and merge on the upper rise forming relatively few canyons that extend seaward. Axial gradients of slope valleys are variable, steep to low, less than 6°, whereas valley axial gradients on the rise are very low, commonly less than 1°. Slope morphology is strikingly different from upper rise morphology--a function of a much higher frequency of valleys with steep walls as compared to the upper rise. End_of_Article - Last_Page 1667------------