Sea Floor Spreading and Continental Drift

I/Seismic Geography. Bathymetry of the Oceans.- General remarks.- tertiary foldings.- transcurrent faults.- island arcs.- the ridge crests.- bathymetry of the oceans.- the focal mechanism of earthquakes and the direction of tectonic stress.- II/Results of Magnetic Measurements at Sea. Transverse Fractures.- The magnetic anomalies of the ridges.- linear anomalies in the neighborhood of island arcs and coasts.- the east pacific rise and the great transcurrent fractures.- active and fossil fractures.- return to the east pacific rise.- III/Reversals of the Earth’s Magnetic Field. The Vinematthews Hypothesis.- Remanent magnetization of lavas and the magnetic field in the past.- periods of polarity and intervening events.- magnetization of ocean sediments and various phenomena connected with reversals.- theoretical examination of the origin Of reversals.- vine-Matthews hypothesis.- transform faults.- focal mechanisms of earthquakes occurring on ridges.- IV/Ocean Spreading.- From ridges to trenches.- simple examples of expansion.- expansions without ridges.- local changes in the rate of expansion.- worldwide variations of expansion.- overall pattern of the anomalies.- their enumeration and dating.- V/Continental Drift.- Floor spreading, drift, and paleomagnetism.- reconstruction of continental blocks.- the hypothesis of rigid plates.- kinematic considerations and the first applications of the plate hypothesis.- the synthesis of le pichon.- ancient spreadings.- VI/Study of the Oceanic Crust by Seismic Refraction and Gravimetry.- Seismic refraction. crustal structure, seismic study of the ridges.- dredging of igneous rocks.- transverse fractures and the seismic anisotropy due to sea floor spreading; gravimetric study of ridges and grabens.- continental margins.- complete studyof trenches.- VII/Heat Flow Through the Ocean Floor.- World heat flow distribution.- heat flow on the ridges.- interpretation of the results.- VIII/The Nature of the Upper Mantle, and Theories of Convection.- Thermal convection, cause of ocean spreading.- properties of the upper mantle given by seismology.- temperature and composition of the upper mantle.- rheology of the mantle.- convection by vertical instability.- convection by gorizontal instability.- IX/Oceans and Continents. Conclusion.- Birth of the oceanic crust.- death of the oceanic crust.- the ocean floor as a conveyor belt conclusion.- X/Recent Progress.- magnetic anomalies and the sea floor.- ridges andrifts, transform faults.- compressive boundaries.- kinematics of plate motions.- dynamics and thermodynamics of plate motions.- terrestrial heat flow.- epicontinental seas.- gravity anomalies and plate theory.- orogenesis on the plate theory.- application of plate tectonics to ancient continental movements.- References.