Paleomagnetism, polar wandering, and the rejuvenation of crustal mobility

The decade from 1951 to 1961 witnessed the birth of a new geophysical subdicipline, paleomagnetism. Early studies in Europe, North America, and Australia led to the following conclusions: (1) rocks could preserve directions of magnetiziation for hundreds of millions of years in red beds, (2) late Cenozoic lavas had directions of magnetiziation that led to the conclusion that the mean geomagnetic field was a geocentric dipole aligned along the axis of rotation, (3) rocks of Triassic age and older yield directions which depart widely from the present axis of rotation, (4) if these directions are used to calculate pole positions, then poles for older and older rocks fall farther and farther from the present pole of rotation, (5) these data may be used to construct polar wander curves, (6) polar wander curves from different continents do not coincide with one another, (7) they may be reconciled if the continents move with respect to each other, and (8) the distribution of climatic indicators show that the pole of rotation of Earth and the paleomagnetic pole for the same periods coincide for Phanerozoic time. These observations changed the perspectives of many Earth scientists and paved the way for seafloor spreading and plate tectonics.