SUCCESSES AND FAILURES IN GEODYNAMICS: FROM PAST TO FUTURE

Abstract

The evolution of Earth models is reviewed and the open questions and problems are highlighted. Generally, evolution of science was not linear, but proceeded in “steps” of paradigms; where old ones remained within useful limits. “Geodynamic hypotheses”, while embedded into the general concepts of space and time, were often mutually exclusive and competing until the 1900s. Wegener's concept of continental drift was the first successful globally unifying view, but it was discarded by most Earth scientists. The “real” change of paradigms did not come before mid-century through geophysical observations in paleomagnetism, seismology, bathymetry, seafloor geology and dating, leading to the “New Global Tectonics” of seafloor spreading and plate tectonics. Although real-time plate kinematics is now firmly established through direct geodetic observations from radio-astronomy and with the aid of artificial satellites, knowledge is incomplete and must be continually “updated”. Quite a number of problems are not yet solved. These may, some day, lead to another change of paradigms, but certainly not back to “fixism”. Problems are related to scale, frame of reference, and especially dynamics. However, plate tectonics is presently the most successful theory in the history of geology. Further developments will be driven by discoveries of apparent dilemmas, contradictions and paradoxes.