A 12-channel seismic-reflection survey over parts of the head of Wilmington Canyon and the surrounding shelf revealed four major buried valleys and many small channels. The data indicate that the ancestral Delaware River valley was the most recent of a series of valleys to enter the canyon from the west. The head of Wilmington Canyon probably was eroded and then filled at various times from late Miocene to late Pleistocene time. Thick sedimentary sequences indicate a sediment supply from both the north and west. A large buried valley entering the canyon from the north was not mapped with the data presented here, but it is possible that such a valley exists. This is one of the first documentations of the long history of erosion of the United States east coast canyons.