Quaternary Geodynamics in Canada
This chapter provides a rather modest introduction to the extensive Quaternary data base which currently exists and to the geophysical models which have been developed to interpret these data; it is clear that an active interplay between theory and observation is desirable. The Quaternary geological data can be brought to bear upon several vital geodynamic issues, including the question of the variation of mantle viscosity with depth, the question of the thickness of the continental lithosphere, and the question of the nature of the discontinuities in elastic parameters which are observed seismically to occur at depths of 420 and 670 km in the earth. All of these questions are of importance in attempting to understand the nature of the convective circulation in the mantle which is responsible for continental drift and seafloor spreading; the Quaternary geological record has begun to provide crucial information with which it will be possible in future to further refine our understanding.
This limited space does not allow all areas of Quaternary geodynamic research to be dealt with adequately. Some aspects not dealt with are: (1) the manner in which the isostatic adjustment process may serve to cause earthquakes by the reactivation of slip on old faults located near the ice sheet margin; (2) the manner in which the grauitationally self-consistent model of relative sea level variation may be employed to filter the modern tide gauge data to reveal more clearly the presence of any currently ongoing “eustatic” component of sea level rise due to, for example
Figures & Tables
The three major sections of this volume include six chapters describing the regional Quaternary geology of Canada, two describing the Quaternary geology and climatic history of Greenland, and six that review applied Quaternary geology in Canada, including chapters on paleobotanical analysis, geodynamics, geomorphic processes, terrain geochemistry, Quaternary resources, and the influence of the Quaternary on the present environment. Of the five accompanying plates, three depict eleven stages of Quaternary paleogeographic change between 18,000 B.P. and 5,000 B.P.; one depicts the retreat of the ice from between 18,000 B.P. and the Recent; and another reviews the status of Quaternary geologic mapping in Canada, with an extensive bibliography on the back.