HARRY HESS'S 1962 SEA FLOOR SPREADING IMAGE: INITIATOR OF THE PLATE TECTONIC REVOLUTION

In the late 1950's, geology was in a crisis in the sense of T. H.Kuhn (1970). New information on polar wander paths of continents and young ocean basins contradicted old ideas of fixed continents and permanent oceans basins but no new global Earth model had yet been formulated. A speech by S. W. Carey in December, 1959, led to a new insight by H. H. Hess, who proposed continental drift by ocean floor spreading caused by mantle convection. Hess's (1962) diagram of sea floor spreading was the first of many illustrations in the unfolding plate tectonic revolution. Subsequent analyses and diagrams related magnetic reversals to sea floor spreading (e.g. Vine and Matthews, 1963, Vine, 1966); combined sea floor spreading with geophysical evidence of the existence of lithospheric plates and outlined principles of "New Global Tectonics" (e.g. Isacks, et al., 1968; Morgan, 1968; McKenzie and Parker, 1967). Application of Hess's ideas to ophiolites, known for over a century in Earth's orogenic belts, led to their reinterpretation as fragments of ocean crust and mantle formed at spreading centers and preserved on land (e.g. Hess, 1965, Moores and Vine, 1969, 1971, Moores, 1969, 1970; Dewey and Bird, 1970; Coleman, 1971). Presence of serpentinites on Mars (Guillot and Hattori, 2013) suggests exposure of ultramafic rocks on the Martian surface and supports a suggestion of short-lived plate tectonic activity on that planet (Yin, 2013). Hess's 1962 diagram arguably inspired geoscientists as geology progressed into the Plate Tectonics Revolution, going from a static to a mobile Earth.