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Archaeomagnetic dating limitations definition

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Archaeomagnetic dating is the study and interpretation of the signatures of the Earth's magnetic field at past times recorded in archaeological materials. These paleomagnetic signatures are fixed when ferromagnetic materials such as magnetite cool below the Curie pointfreezing the magnetic moment of the material in the direction of the local magnetic field at that time.

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The direction and magnitude of the magnetic field of the Earth at a particular location varies with timeand can be used to constrain the age of materials. In conjunction with techniques such as radiometric datingthe technique can be used to construct and calibrate the geomagnetic polarity time scale. This is one of the dating methodologies used Archaeomagnetic dating limitations definition sites within the last 10, years.

Thellier in the s [2] and the increased sensitivity of SQUID magnetometers has greatly promoted its use. The Earth's magnetic field has two main components. Within these weaker areas the local directions and intensities change gradually secular variation.

Thus a practical precision limit...

A compass does not point to the true North Pole but to direction that is a function of the North Magnetic Pole and the local secular variation to yield a magnetic declination. The magnetic declination at any given time can be frozen into a clay formation that contains magnetite and is heated above the Curie point. In general, many cultures used long-term fire hearths made of clay bricks, or a space lined with clay, that Archaeomagnetic dating limitations definition baked into place by use.

These artifacts of occupation can yield the magnetic declination from the last time they were fired or used.

Archaeomagnetic Dating

Magnetic Domains to Geologic Terranes. Archaeomagnetic dating requires an undisturbed feature that has a high likelihood of containing a remnant magnetic moment from the last time it had passed through the Curie point. This involves sufficient mass to take samples from, and a suitable material with adequate magnetite to hold the remnant magnetism. In addition, the feature needs to be in an area for which a secular variation curve SVC exists.

Once the paleodirections of enough independently dated archaeological features are determined, they can be used to compile a secular variation record for a particular region, known as an SVC. "Archaeomagnetic dating limitations definition" Archaeomagnetic Laboratory at the Illinois State Museum has secular variation curves for the southwest, mid-continent and southeast United States.

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