What is Paleomagnetism?
Magnetic Polarity Time Scale: 0-65 Ma
Cooper, R.A., Agterburg, F.P., Alloway, B.V., Beu, A.G., Crampton, J.S., Graham, I.J., Naish, T.R., Sadler, P.M. & Wilson, G.S., 2004. Chapter 1, Introduction. in Cooper, R.A. (ed.), 2004. The New Zealand Geological Timescale. Institute of Geological and Nuclear Sciences Monograph 22, pp. 1-28.
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Paleomagnetism as a Dating Indicator
Paleomagnetism is a proven tool for documenting and more precisely dating indicators of climate, earth deformation and changes in the natural environment from sedimentary sequences.
The earth's magnetic field is constantly changing. Essentially, it has two stable orientations - a "normal" field where North magnetic and geographic poles coincide, and a "reversed" field where the magnetic and geographic poles are opposite. - and it oscillates between the two.
This random reversal pattern of the earth's polarity provides a unique record - one that is key to palaeomagnetism. Charting the long-term history of the earth's geomagnetic field, by recording fossil magnetism in rocks and sediments, enables us to determine when the sediment was deposited. Individual sediment layers as old as 100 million years can be dated to a precision of less than a thousand years.