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The Brunhes–Matuyama reversal, named after Bernard Brunhes and Motonori Matuyama, was a
geologic Geology (). is a branch of natural science concerned with the Earth and other astronomical objects, the rocks of which they are composed, and the processes by which they change over time. Modern geology significantly overlaps all other Earth s ...
event, approximately 781,000 years ago, when the
Earth's magnetic field Earth's magnetic field, also known as the geomagnetic field, is the magnetic field that extends from structure of Earth, Earth's interior out into space, where it interacts with the solar wind, a stream of charged particles emanating from ...
last underwent reversal. Estimations vary as to the abruptness of the reversal. A 2004 paper estimated that it took over several thousand years; a 2010 paper estimated that it occurred more quickly, perhaps within a human lifetime; a 2019 paper estimated that the reversal lasted 22,000 years. The apparent duration at any particular location can vary by an order of magnitude, depending on geomagnetic latitude and local effects of non-dipole components of the Earth's field during the transition. The Brunhes–Matuyama reversal is a marker for the
Global Boundary Stratotype Section and Point A Global Boundary Stratotype Section and Point (GSSP), sometimes referred to as a golden spike, is an internationally agreed upon reference point on a stratigraphic section which defines the lower boundary of a stage on the geologic time scale. ...
(GSSP) defining the base of the
Chibanian The Chibanian, more widely known as the Middle Pleistocene (its previous informal name), is an Age (geology), age in the international geologic timescale or a Stage (stratigraphy), stage in chronostratigraphy, being a division of the Pleistocen ...
Stage and
Middle Pleistocene The Chibanian, more widely known as the Middle Pleistocene (its previous informal name), is an Age (geology), age in the international geologic timescale or a Stage (stratigraphy), stage in chronostratigraphy, being a division of the Pleistocen ...
Subseries at the Chiba section, Japan, which was officially ratified in 2020 by the
International Union of Geological Sciences The International Union of Geological Sciences (IUGS) is an international non-governmental organization devoted to global cooperation in the field of geology. As of 2023, it represents more than 1 million geoscientists around the world. About Fo ...
. It is useful in dating ocean sediment cores and subaerially erupted volcanics. There is a highly speculative theory that connects this reversal event to the large Australasian strewnfield (c. 790,000 years ago),Glass, B. P., Swincki, M. B., & Zwart, P. A. (1979)
"Australasian, Ivory Coast and North American tektite strewnfields – Size, mass and correlation with geomagnetic reversals and other earth events"
Lunar and Planetary Science Conference, 10th, Houston, Tex., March 19–23, 1979, pp. 2535–2545.
although the causes of the two are almost certainly unconnected and only coincidentally happened around the same time. Adding to the data is the large African Bosumtwi impact event (c. 1.07 million years ago) and the later Jaramillo reversal (c. 1 million years ago), another pair of events which has not gone unnoticed.


See also

* Bosumtwi impact event * Gauss–Matuyama reversal *
Geomagnetic reversal A geomagnetic reversal is a change in the Earth's Dipole magnet, dipole magnetic field such that the positions of magnetic north and magnetic south are interchanged (not to be confused with North Pole, geographic north and South Pole, geograp ...
* Jaramillo reversal * List of geomagnetic reversals


References


Further reading

*Behrendt, J.C., Finn, C., Morse, L., Blankenship, D.D. "
One hundred negative magnetic anomalies over the West Antarctic Ice Sheet (WAIS), in particular Mt. Resnik, a subaerially erupted volcanic peak, indicate eruption through at least one field reversal
'" University of Colorado, U.S. Geological Survey, University of Texas. (U.S. Geological Survey and The National Academies); USGS OF-2007-1047, Extended Abstract 030. 2007. Pleistocene Geomagnetic reversal Magnetic field of the Earth {{geophysics-stub