Scripps Institution of Oceanography, United States

The shallow stratigraphy of the New Jersey continental margin is revealed by sediment recovered with the R/V Marion Dufresne and during ODP Legs 150 and 174A. Shelf facies are dominated by sand beds and sands with soft sediment deformation that contain clasts of Cretaceous to Pleistocene age. The age of the clasts suggests that these chaotic sands were transported from the coastal plain across the shelf by rivers. These massive shelf sands were deposited during glacial times and are interpreted as prodelta facies. Widespread erosion and sediment failure are documented along intercanyon regions of the continental slope. Oxygen-isotope stratigraphy calibrated with radiocarbon ages indicates that the Holocene is missing from the slope (Site 1073). A sharp contact at 20cm below the seafloor indicates erosion. Other studies have shown that Stages 1-5 are missing from the nearby slope (Sites 902-903), presumably due to erosion. Sediment facies in intercanyon areas contain soft-sediment deformation and clay clasts, which are the same age as that of the matrix. These sediments are interpreted as muddy slumps and debris flows derived from localized slope failures. These events occurred during both glacial and interglacial phases. The continental slope is deeply incised by complex submarine canyon systems, which were actively excavated during the Pleistocene. Some canyons have been infilling. For example, Berkeley Canyon contains 50 m of debris-flow deposits capped by 5 m of hemipelagic clay. In contrast, Alvin Dives show Eocene chalks exposed along the floor of Hendrickson Canyon. Backscatter patterns on GLORIA images mark the paths of Pleistocene mass-transport deposits extending from the canyon mouths across the continental rise where the thickest (215 m) and most complex deposits have been cored (Site 905). Alvin Dives and camera surveys across the lower slope and rise show large talus blocks partially covered by pelagic sediment.