Polar wander

Polar wander is the motion of a pole in relation to a fixed reference frame. It can be used, for example, to measure the degree to which Earth's magnetic poles have been observed to move relative to the Earth's rotation axis. It is also possible to use continents as a static entity and observe the relative motion of the magnetic pole on the different continents; by doing so, the relative motion of those two continents to each other can be observed over geologic time.

The magnetic poles are relatively stationary in position over time and because of this, researchers often use magnetic minerals, like magnetite, in order to find at what latitude the continent was positioned relative to the magnetic poles of that time. Since the continents have been moving relative to the pole; it is as if they were immobile and the magnetic pole was moving instead. If enough data is collected, it is then possible to reconstruct the motion of the continents relative to the magnetic poles. The apparent polar wander is the path that the magnetic pole appears to take according to the data on a continent. When multiple continents are moving relative to each other, the path their magnetic pole will follow will be different from the others. Conversely, when two continents are moving parallel to each other their path will be the same.

True polar wander represents the shift in the geographical poles relative to Earth’s surface, after accounting for the motion of the tectonic plates. This motion is caused by the rearrangement of the mantle and the crust in order to align the maximum inertia with the current rotation axis (fig.1). This is similar to a spinning top; when its rotation is disturbed, it slowly recovers and it will realign its rotation axis to its position of maximum inertia. The difference is that unlike Earth, the spinning top’s mass distribution is constant through its volume over time. Evidence for true polar wander has been observed from the study of large apparent polar wander datasets which, when corrected for the motion of the magnetic pole, display this polar wander. Modern polar wander can be evaluated from precise measurement using stars or satellite measurements, however filtering to remove the wobble of the Earth is required. The formation of supercontinents could initiate a faster polar wander. That is, because the supercontinent creates an extra mass concentration where they are located, the planet tries to re-orient the supercontinent towards the equator.

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