Archaeomagnetic dating Archaeomagnetic dating uses the ability of certain materials to record the Earth's magnetic field (geomagnetic field) to provide a date.The Earth's field changes in both strength (intensity) and direction over time.By tracking and cross-dating past changes in the location of the magnetic field, geophysicists have reconstructed a series of magnetic polar positions extending back more than 2,000 years. At archaeological sites, hearths constructed of iron-bearing clays are ideal for archaeolomagnetic sampling because they were subjected to repeated hot firings.This series of dated positions is known as the "archaeomagnetic reference curve." (Stacey Lengyel, 2010.
Archaeomagnetic dating works because the earth’s magnetic field "wanders," continually changing its position in response to changes in the flow of liquid iron in the planet's core. As the clay cools, the alignment of the iron “fixes,” preserving a record of the magnetic field at a specific time in the past.If the magnetism recorded within an archaeological material is compared with a record of the changes in the Earth's ancient field (geomagnetic field ), a date can be produced.Archaeomagnetic dating is a derivative dating method.Directions to the east of true north are positive, directions to the west are negative.Demagnetisation Action to eliminate the remanent magnetisation of a sample.Geomagnetic field The Earth's magnetic field that resembles the field of a centric magnetic dipole inclined about 11.4° to the rotation axis of the Earth.