Reference Work Entry

Structural Geology and Tectonics

Part of the series Encyclopedia of Earth Science pp 15-18

Apparent polar wander

  • Rob Van Der Voo

Apparent polar wander (APW) can be defined as the movement of the pole with respect to a given tectonic element (plate, continent, craton, block, etc.) that is assumed to be fixed in the present-day geographic coordinate system. Since most of the evidence for APW has come from paleomagnetism (the study of the remanent magnetization in rocks), the pole referred to here is the magnetic pole. However, it is assumed that the magnetic polar axis, on the average, coincides with the rotation axis of the Earth, so APW may also refer to the geographic pole. Paleomagnetic studies of Late Tertiary to Recent rocks and studies of paleoclimates and paleolatitudes support this assumption (Irving, 1964; McElhinny, 1973).

There are two methods of presenting paleomagnetic information for the geological past. By measuring the direction of the magnetic vector in rock samples and by carefully applying reliability criteria to these measurements, paleomagneticians can deduce the orientation and ...

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