Assertion: magnetic field's pole | /r/CapableOf | migrate over the course of a few hundred
Facets:
value: from one orientation
type: OTHER
value: spontaneously
type: TEMPORAL
Source sentences:
text: Some scientists have produced models for the core of the Earth wherein the magnetic field is only quasi-stable and the poles can spontaneously migrate from one orientation to the other over the course of a few hundred to a few thousand years.