Archaeomagnetic dating

Posted by / 01-Dec-2020 13:29

Archaeomagnetic dating

The discs are marked with a line which points towards the present position of the magnetic pole - which is measured with a highly accurate compass.Then the discs and the small blocks of soil attached beneath them are carefully removed.Samples have been taken for both archaeomagnetic and radiocarbon dating, and the results are compared.Close agreement is observed between both techniques, with the archaeomagnetic age of AD 603999 overlapping the calibrated age of AD 770890.

Small samples of soil or burnt building materials are prepared in situ by having small plastic discs glued to the surface of the layer.In the lab afterwards, the difference in orientation between the line showing the present magnetic pole and the orientation of the magnetised particles in the soil, reflecting the pole's position at the time of burning, can be determined.These differences in magnetic orientation, which can give us an accurate date, are compared to a known curve of the movement of the earth's magnetic pole.The curve has been well-documented for Britain, but in many other areas of the world there is a lot less certainty in using this technique.Reference archaeomagnetic secular variation (SV) curves recently have been proposed for the Iberian Peninsula and may now be used for archaeomagnetic dating.

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The pole moves around, but magnetised deposits stay fixed on its position at the time of burning.