Swath Bathymetry

Swath bathymetry and derivative products such as slope, hillshaded relief, and rugosity maps provide information not only on water depth, but also the roughness and smoothness of the sea floor, which correlates with sea floor texture and depositional environment. The shaded-relief bathymetry image of the sea floor offshore of northeastern Massachusetts between Cape Ann and Salisbury Beach is colored to represent depths in meters, relative to the local mean lower low water (MLLW) datum. Rocky areas are readily distinguishable from sand areas in shaded relief imagery.  Fine-grained deposits on the inner continental shelf  are characterized by smooth contours; for example, the southeastern part of the study area in water depths greater than 40-meters. Rock and coarse grained material are associated with crenulated contours and rugged topography; for example, the sea floor just offshore of the Massachusetts-New Hampshire border.