December 09, 2012
Hangi stones track earth magnetic flows
Scientists are using ancient hangi stones to track changes in the earth’s magnetic field.
Dr Gillian Turner from Victoria University says in other parts of the world pottery is used to build up historical data.
That’s because when pottery is fired, the minerals in the clay are demagnetised.
As they cool they pick up a charge again in the direction of the prevailing magnetic field.
Dr Turner says the lack of pottery in the southwest Pacific meant a gap in the international record, until her team discovered the same effect in the cooking stones used for earth ovens, especially the volcanic boulders preferred by Māori.
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