Palaeomagnetism is the study of past magnetic fields recorded by geological or archaeological material, also spelled paleomagnetism. A measured direction or polarity can be compared with a dated regional or global magnetic sequence to constrain an event's age.
The magnetic component must belong to the event being dated: subsequent heating or chemical change can produce remagnetization. Laboratory separation of magnetic components and independent geological relationships are therefore part of the dating argument.[ref]
Rocks and Paleomagnetics Laboratory by United States Geological Survey. Research uses and separation of original and secondary magnetizations
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