Geomagnetic field reversal

Significant deficiencies are present in the physical dating methods used to infer temporal relationships for the paleoanthropological and archaeological record for the whole of the Middle Pleistocene (about 730,000 to 125,000 B.P.) (11), and for the interval of time up to the initiation of the 14C time scale. There are no recognized major reversals of the earth s geomagnetic field after 730,000 years ago. Many important sites are not in areas of vol-canism, and even for those that are, there are often serious analytical prob-... 

Palaeomagnetic Secular Variation (PSV) Regional, short lasting fluctuations (lO to in years), of the geomagnetic field of smaller amplitude than those involved in complete reversals of the Earth s geomagnetic field. 

The study of palaeomagnetism has extended knowledge of the secular magnetic variation into the geological past and it is clear that the direction of the geomagnetic field has reversed many times. The source of the field and the cause of the variations are not known with any certainty but the source is believed to be associated with dynamo action in the earth s liquid core. 

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