<P> Paleomagnetism ( or palaeomagnetism in the United Kingdom ) is the study of the record of the Earth 's magnetic field in rocks , sediment , or archeological materials . Certain minerals in rocks lock - in a record of the direction and intensity of the magnetic field when they form . This record provides information on the past behavior of Earth 's magnetic field and the past location of tectonic plates . The record of geomagnetic reversals preserved in volcanic and sedimentary rock sequences ( magnetostratigraphy ) provides a time - scale that is used as a geochronologic tool . Geophysicists who specialize in paleomagnetism are called paleomagnetists . </P>
paleomagnetism is a dating method based on changes in the earth 's polarity as demonstrated by
volcanic and sedimentary rock sequences ( magnetostratigraphy )