SEISMOLOGY, THE PLATE-TECTONICS REVOLUTION, AND MAKING IT HAPPEN AGAIN

In keeping with the nature of the symposium, part I is a brief summary of the author's recollection of research activities in earthquake seismology at the Lamont Geological Observatory that contributed to the development of the concept of plate tectonics in the 1960's. As the productive and euphoric period of the late 1960's that marked the advent of plate tectonics waned, it was followed in the 1970's and 1980's by various efforts to cause yet another major advance in earth science. One focus of such efforts was, and is, the continental crust. A new paradigm has not yet appeared, but part II describes how the earth scientist's perspective of the continents is changing as a consequence of those efforts. Surface geology can now sometimes be extrapolated to the base of the crust. Comprehensive global exploration of the entire volume of the continental crust has become a reasonable and achievable goal. The Moho, the traditional crust-mantle boundary, is recognized as a dynamic feature and no longer is considered the lower bound of the continent. Fluids propagating for long distances horizontally in the crust may link a variety of geologic phenomena with the large-scale geodynamic processes of the interior. The story of the earth's slowly evolving continents is rapidly evolving.