North Canary Basin, 12 Northeast Providence Channel, 35, 36 Northwest Atlantic Mid-Ocean Canyon, 22, 67, 68, 69, 70, 71 Ocean-basin floor, 1, 15, 25, 55-82, 102, 107 abyssal floor, 1, 15, 55-74 crustal structure, 80-81, 102 oceanic rises, 1, 15, 55, 74-78 seamounts of, 78-79 seismicity of, 80 Oceanic crust, 80-81, 100, 102 Oceanic rises Bermuda Rise, 74-77 Corner Rise, 64, 77 definition, 74 distribution, 74 Rio Grande Rise, 74 Rockall Rise, 78 Oceanographer Canyon, 43 Old Bahama Channel, 36 Olivine gabbro, 99 Orthogeosyncline, 54 Orthoquartzite, 53 Outer ridges Antilles Outer Ridge, 32, 33, 36, 52, 53, 59, 60 definition, 20 sediments on, 53 Southeast Newfoundland Ridge, 22, 63, 67, 70, 71, 72 Paleozoic outcrops, 99 Pelagic deposits, 53, 81, 99, 107 Photographs, sea floor, 39, 50, 59, 79 Physiographic diagram, preparation of, 3, 4, 5 Physiographic province chart, Atlantic Ocean, 3, 16 Plant debris, 60 Plato Seamount, 98 Pleistocene beaches, submerged, 42 Portuguese submarine canyons Lisbon, 37 Nazaré, 37 Setúbal, 37 Precision Depth Recorder (PDR) accuracy of, 8 development of, 8 operation of, 9 positions of PDR sounding tracks, 6 Precision Depth Recorder (PDR) records, 28, 32, 34, 36, 38, 58, 64, 73, 78, 91, 92 Puerto Rico Trench, 36 Puerto Rico (Trench) Abyssal Plain, 17, 36, 52, 56, 60 Recent sediments, erosion of, 50 Red clay, 33, 76, 106 Reflections, sub-bottom, 25, 32, 41, 105-106 Research vessels ALBATROSS III, vii ATLANTIS, vii, 7, 8, 79 CARYN, vii, 78 DISCOVERY II, vii KEVIN MORAN, 70 METEOR, 83, 98 TALISMAN, 99 THETA, vii, 2, 7 VEMA, vii, 6, 72 Rift Mountains, 1, 15, 84, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 107 Rift Valley, 1, 15, 84, 90, 91, 93, 94, 95, 96, 98, 99, 100, 101, 102, 103, 107 Rio Grande Rise, 74 Ripple Marks, 39, 50, 51, 59, 79 Rock dredging, 39, 42, 43, 45, 46, 47, 76 Rockall Rise, 78 Sable Island, 24 Sable Island Bank, 24 Sand, deep-sea, 28, 60, 61, 74 Scarps, 61 Abyssal Plain, 61 Bermuda Rise, 76 Mid-Atlantic Ridge, 83 Scotian Shelf, 23, 24 Scour marks, photographs of, 39, 59 Seamounts Ampere, 78 Atlantis, 98 Caryn, 78 Cruiser, 98 Great Meteor, 98 Josephine, 78 Kelvin, 77, 78 Milne, 79 Muir, 76 Plato, 98 Seamount Groups Atlantis-Plato-Cruiser-Great Meteor Seamount Group, 98 Horseshoe Seamount Group, 59, 78 Kelvin Seamount Group, 76, 77, 78 Muir Seamount Group, 76 Seamounts, sedimentary processes on, 59, 77 Sediment distribution abyssal plain, 74 Bermuda Rise, 76 continental margin, 53 correlation with topography, 107 map of North Atlantic, facing page, 122 Mid-Atlantic Ridge, 99