Richter, C. F., 20, 22 



"Ridges" of the continental slope, 115 



Rio Grande Valley, 146 



Romieux, J., 144, 166 



Roots of mountain chains, 85, 96 



melting of, 93 



thermal expansion of, 92 

 Roti Island, 95 

 Russell, R. J., 101, 166 

 Russia, glacial moraines in, 34 

 Rutherford, H. M., 106, 166 



Oaint Helena Island, 50, 63 

 Salinity, excess, a cause of density cur- 

 rents, 141 ff, 150 

 Saluda Reservoir, 147 

 Samoa, 50, 55 



Sampling the sea floor, 8, 11, 12 

 San Carlos Reservoir, 147 

 Sandstorm near Khartoum, 137 

 Sao Miguel Island, a test of crustal 



strength, 63 

 Saumlaki Island, deformed rocks in, 89 

 Sea bottom, varied relief of, 48 

 Sea of Japan, 91 

 Sealevel, eustatic (world-wide) shifts of, 



128, 131, 136 

 Sediment, mechanism for transport of, to 



deep water, 156 

 "Sediment transports water," 141 

 Seismogram, 11, 13, 21 

 Seismogram of the recent earthquake in 



Turkey, 15 

 Seismograph, detection with the, 13, 18, 



21, 106 

 Self-acceleration of bottom currents, 138, 



150 

 Seychelles Bank, 67 

 Seychelles Islands, 23 

 Seychelles Plateau, 23, 24 

 Shake waves, 14, 18, 47 

 Shepard, F. P., on submarine vall< 



124 ff, 128, 131, 152, 166 

 Shoals, 9, 48, 50, 97 



development of, 51, 65, 70 

 Sial 



defined, 17, 18, 33, 46, 49 



of Atlantic and Indian Ocean basins 



INDEX 175 



original thickness in East Indian re- 

 gion, 94 



thickened in belts of mountain-build- 

 ing, 88, 89 

 Sibcroet Island, deformed rocks in, 89 

 Sicily, thickness of the crust under, 61 

 Silty currents. See Density currents 

 Sima, defined, 17, 18 

 Simatic crust, 33, 46, 49, 59 

 Sipoera Island, deformed rocks in, 89 

 Slopes. See Gradients 

 Smith, J. F., 162 

 Smith, P. A., investigator of submarine 



valleys, 115, 122, 140, 161, 166 

 Snake River Canyon, compared with 



submarine canyons, 122, 123 

 Society Islands, 50 

 Soembawa Island, 89 

 Sonic sounding, 6 

 South Africa, 8 

 South Georgia, relation to mountain-arc, 



82 

 South Sandwich Islands, relation to 



mountain-arc, 82 

 Southwest Pacific, velocities of earth- 

 quake waves under, 18, 20 

 Spheroid, oblate, 25 

 Spheroid, standard, 25 

 Spirit-level, showing recent changes of 



level, 39 

 "Spring-sapping," a suggested origin of 



submarine valleys, 132, 134 

 Stability of volcanic islands, 65 ff, 67 

 Stereogram of earth-shells, 46 

 Stetson, H. C, investigator of continental 



terrace, 100, 124, 128, 153, 166 

 Stevenson, R. L., 51 

 Strength 



of crust, 33, 62, 74, 77 



of earth-shells under Fennoscandia, 43 



of earth-shells under Hudson Bay, 44 



of rock in relation to pressure, 62, 78, 



97 

 Stress 



caused by deglaciation, 40, 42 



causing isostatic adjustment, 32, 42 

 "Strips" of deficient mass (negative 



anomalies of gravity), 82 



origin of, 86, 95 

 Subaerial and submarine bottom currents 



compared, 139 ff 



ys, 



