Continental DriftAlfred Wegener (1912) First serious proponent Took time to look carefully at

the data & carefully study it Many scientists have ideas

and don't follow up Many geologists were more

familiar with the data, but couldn't bring themselves to believe it

Wegener looked at the facts in the perspective of the theory & looked for consistencies

Alfred manning the weather station, Greenland - 1913

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 EvidenceGlossopteris: an ancient seed fern(200 Ma)

Distribution of Glossopteris fossils

Fossil Evidence

Mesosaurus couldn’t swim in open ocean

Distribution of Mesosaurus fossils

PaleomagnetismThe Earth as a dipole

Magnetic declination and inclination

PaleomagnetismMagnetization of volcanic rocks and sediments

Paleomagnetism“Polar Wandering” curves

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