HR: 08:35h
AN: U31B-03    [Abstracts]
TI: Paleogeography, Plates and the Role of Latitude
AU: * Irving, E
EM: tirving@pgc-gsc.nrcan.gc.ca
AF: Geological Survey of Canada, PO Box 6000, North Saanich, BC V8L4B2 Canada
AB: In the 1920s, Wegener, Koppen and Argand created the first mobilistic paleogeography, which for many reasons did not prosper. Mobilism was revived in the 50s and 60s through measurements of long-term motion of crustal blocks relative to earth's spin axis (apparent polar wander APW and latitude change, 1954) and relative to each other (plate tectonics 1967/8). In the past decade, seismic and geodetic arrays and campaigns have observed compatible short-term motions. Creer's discovery of apparent polar wander (APW) which we celebrate today, initiated the development of a new mobilistic paleogeography based on physical measurement of latitude change and rotation of crustal blocks; attempts to make unambiguous reconstructions encountered difficulties not the least of which was the adamantine fixism of earth science institutions. However, the advent of plate tectonics a decade later (1967/8) provided the natural spherical framework for integrating not only measurements of tectonic motion on which it was initially based, but also APW and measurements of latitude change; this was done regionally in 1971 and globally in 1973. At this point the new paleogeography can be said to have matured; over the last 30 years it has become the basis for reconstructing the evolution of earth's surface features vital for understanding evolution of life, long-term climate change, measuring large-scale deformation in mobile belts, etc. I shall illustrate the key steps in this progression from Creer's first path to the present day.
DE: 1700 HISTORY OF GEOPHYSICS
DE: 1525 Paleomagnetism applied to tectonics (regional, global)
DE: 1527 Paleomagnetism applied to geologic processes
DE: 1560 Time variations--secular and long term
SC: Union [U]
MN: 2004 AGU Fall Meeting