Continental Drift Alfred Wegener (1912) l First serious proponent l Took time to look carefully at the data & carefully study it l Many scientists have ideas and don't follow up l Many geologists were more familiar with the data, but couldn't bring themselves to believe it l Wegener looked at the facts in the perspective of the theory & looked for consistencies Alfred manning the weather station, Greenland
Fit of the Continents A modern view than Wegener’s uses 1000 or 2000 m isobath as estimate of edge of continental crust
Fit of Structural Elements
Pennsylvanian (300 Ma) Glaciation Glacial striations in bedrock, South Australia
Pennsylvanian (300 Ma) Glaciation Using present continental locations Arrows indicate ice movement directions
Pennsylvanian (300 Ma) Glaciation Using pre-drift continental locations Arrows indicate ice movement directions
Fossil Evidence Glossopteris: an ancient seed fern (200 Ma) Distribution of Glossopteris fossils
Fossil Evidence Mesosaurus couldn’t swim in open ocean Distribution of Mesosaurus fossils
Paleomagnetism The Earth as a dipole Magnetic declination and inclination
Paleomagnetism Magnetization of volcanic rocks and sediments
Paleomagnetism “Polar Wandering” curves
l In spite of this data, the theory of continental drift died off in the 1950s, mainly because the geophysicists could not find an adequate mechanism to move the rigid crust and mantle