archeomagnetic dating

archeomagnetic dating

[¦är·kē·ō‚mag¦ned·ik ′dā·diŋ]
(geophysics)
An absolute dating method based on the earth's shifting magnetic poles. When clays and other rock and soil materials are fired to approximately 1300°F (700°C) and allowed to cool in the earth's magnetic field, they retain a weak magnetism which is aligned with the position of the poles at the time of firing. This allows for dating, for example, of when a fire pit was used, based on the reconstruction of pole position for earlier times.