International Hydrographic Bureau (Monaco), vii, 3, 5, 11, 12 Josephine Seamount, 78 KEVIN MORAN, Tug, 70 Kelvin Seamount Group, 72, 77, 78 Labrador Basin, 12 Lahave Bank, 24 Lamont Geological Observatory, 3, 6, 8, 21 Landward slopes of trenches, 1, 19, 36 Laurentian Channel, 23 Lisbon Submarine Canyon, 37 Lower Continental Rise Hills, 56 Lower Step, Mid-Atlantic Ridge, 1, 15, 90, 91, 94, 95, 96 Madeira Abyssal Plain, 56, 58, 61 Madeira Island, profile near, 28, 29 Madeira Rise, 58, 61 Magnetic anomalies continental margin, 51, 52 Mid-Atlantic Ridge, 51, 100, 101 ocean-basin floor, 51, 65, 72 seamounts, 51 Magnetic surveys airborne, 51 ship-towed, 51 Manganese nodules, 39, 78 Mantle, 80, 102 Marginal basin-outer ridge complex, 20, 36 Marginal escarpments Bay of Biscay, 19, 37 Blake, 19, 32, 35 Gulf of Mexico, 19, 33 New Zealand, 19 Marginal plateaus, 18, 32, 37 Blake Plateau, 17, 32, 47, 48, 59 Western Europe, 37 Marginal trenches, 20, 36, 53, 107 filled, 52-54 Pacific, 19, 60 Puerto Rico Trench, 17, 36, 52, 56, 60 Marginal trench-outer ridge complex, 1, 20, 36, 53 Matawan (Cretaceous) formation, 44, 45, 46 Mercator projection, 3 METEOR, Research Vessel, 83, 98 Mid-Atlantic Ridge axial profile, 96 crest provinces, 1, 84 flank provinces, 1, 95 heat flow, 103 High Fractured Plateau, 1, 90, 94, 95 limits of, 83 Lower Step, 1, 90, 94, 95 Middle Step, 1, 90, 94, 95 ocean-bottom photographs, 78, 99 origin of, 103 rocks of, 99 Rift Mountains, 1, 90, 92, 94 Rift Valley, 1, 84, 90, 91, 92, 93, 94 sediments on, 99 seismicity of, 98, 99 structure of, 81, 100, 102, 107 trilobites from, 99 type profile, 90 Upper Step, 1, 90, 94, 95 Mid-Atlantic Ridge Expeditions (1947-48), 99 Middle Step, 1, 15, 94, 95, 96 Mid-ocean canyons Bay of Bengal, 66 Bay of Biscay, 60 deep-sea channels, 66 definition, 66 distribution of, 66-72 equatorial Atlantic, 66 Gulf of Alaska, 66 Mid-Ocean Canyon No. 2., 71-72 Northwest Atlantic Mid-Ocean Canyon, 22, 66-72 Mid-Oceanic Ridge, 1, 15, 83-104, 107 crest provinces, 1, 15, 83 definition, 83 flank provinces, 1, 15, 95 Milne Seamount, 79 Morpho-tectonic provinces, 2 MUIR, U.S.S., 76 Nares Abyssal Plain, 56, 57, 59, 74, 81 National Geographic Society, vii, 99 Navarro (Cretaceous) formation, 44, 45, 46 Navidad Bank, 34, 36 Navigational control, accuracy of, 5 Nazaré Submarine Canyon, 37 Newfoundland Abyssal Plain, 56, 58 Newfoundland Basin, 12, 56, 67, 68, 69, 70, 71 Nomenclature of deep-sea relief 11, 12, 15 North America Basin, 12 North Atlantic Ocean major basins of, 12 map of earthquakes in, facing page, 122 map of sediment distribution, facing page, 122 soundings, 5 structure section, 102