Geomagnetic dating of rocks is possible because directoryofdating com
For tectonic plates with continents, it is possible to measure the present-day motion of the plates using GPS (Global Positioning System).
To measure the motion accurately enough, special GPS measuring stations are established and continuously record the location of the station.
This part of the study was carried out at the ESRF synchrotron facility in Grenoble, France, and this made it possible to observe the changes of the magnetic order in iron oxide.
The surprising result was that the hematite remained magnetic up to a temperature of around 925 °C (1,200 K) -- the temperature prevailing in the subducted slabs beneath the western part of Pacific Ocean at the Earth's transition zone depth.
Earth's mantle, on the other hand, has been considered to be 'magnetically dead' for the most part.Background: The geomagnetic poles of the Earth -- not to be confused with the geographic poles -- are constantly moving.As a result of this movement they have actually changed positions with each other every 200,000 to 300,000 years in the recent history of the Earth.The last poles flip happened 780,000 years ago, and last decades scientists report acceleration in the movement of the Earth magnetic poles.Flip of magnetic poles would have profound effect on modern human civilisation.
Now researchers show that a form of iron oxide can also retain its magnetic properties in Earth's mantle.