As the rotation stabilized over a long time, possibly over one million years, the north-south axis of the moon reoriented and passed through different points on the surface, in a process called "true polar wander
Geophysicists refer to this crustal shifting as true polar wander
. It's the tendency of spinning objects to reorient themselves so that locations with mass excesses end up on the equator and mass deficiencies at the poles.
The idea that the wholesale relocation of Earth's continents 520,000,000 years ago, also known as "true polar wander
," coincided with a burst of animal speciation in the fossil record dates back almost 20 years to an original hypothesis by Joseph Kirschvink, professor of geobiology at the California Institute of Technology, Pasadena, and his colleagues.
Another "new" hypothesis the authors develop in several places is that major events such as the Cambrian explosion and particular extinctions were started by "true polar wander
To define the age of the Listice ChRM component, its VGP was plotted on the apparent polar wander
The amount of crustal shortening can be determined by comparing the paleolatitudes from the present day shaped continents given by the apparent polar wander
paths (APWPs) and the paleolatitiudes of the extended continents.
This strange phenomenon, called "true polar wander
," would normally take millions of years to play out.
In their model, undulating shorelines are a consequence of a phenomenon that astronomers call true polar wander
, in which Mars' axis of rotation slowly drifts in direction.
The location of Tharsis, the largest volcano in the Solar System, provides evidence of the "polar wander
The theory, known as true polar wander
, postulates that if an object of sufficient weight ever formed far from the equator, the force of the planet's rotation would gradually pull it away from the Earth's axis.
Their mass movement within the body of the Earth would affect its rotation and explain polar wander
. (5) On reaching levels of decreased pressure in the upper mantle and lower crust, ionic hydrogen would escape as molecular hydrogen and molecular gases, silane (Si[H.sub.4]) and methane (C[H.sub.4]) in particular.
Detailed studies of the angular relationships of hotspot trails show that the distance to the north magnetic pole, and by assumption the north geographic pole (= spin axis), has changed by up to 8 mm/y over the past 100 Ma, providing evidence for "true polar wander
" or movement of hotspots relative to the geographic pole (Duncan and Richards, 1991).