Antoine Joseph Bernard Brunhes (3 July 1867 – 10 May 1910) was a

French French (french: français(e), link=no) may refer to: * Something of, from, or related to France ** French language, which originated in France, and its various dialects and accents ** French people, a nation and ethnic group identified with Franc ...

geophysicist Geophysics () is a subject of natural science concerned with the physical processes and physical properties of the Earth and its surrounding space environment, and the use of quantitative methods for their analysis. The term ''geophysics'' som ...

known for his pioneering work in

paleomagnetism Paleomagnetism (or palaeomagnetismsee ), is the study of magnetic fields recorded in rocks, sediment, or archeological materials. Geophysicists who specialize in paleomagnetism are called ''paleomagnetists.'' Certain magnetic minerals in rock ...

, in particular, his 1906 discovery of

geomagnetic reversal A geomagnetic reversal is a change in a planet's magnetic field such that the positions of magnetic north and magnetic south are interchanged (not to be confused with geographic north and geographic south). The Earth's field has alternated ...

. The current period of normal polarity, ''Brunhes Chron'', and the

Brunhes–Matuyama reversal The Brunhes–Matuyama reversal, named after Bernard Brunhes and Motonori Matuyama, was a geologic event, approximately 781,000 years ago, when the Earth's magnetic field last underwent reversal. Estimations vary as to the abruptness of the rever ...

are named for him. Brunhes was educated at the

École Normale Supérieure École may refer to: * an elementary school in the French educational stages normally followed by secondary education establishments (collège and lycée) * École (river), a tributary of the Seine flowing in région Île-de-France * École, Savoi ...

Paris Paris () is the capital and most populous city of France, with an estimated population of 2,165,423 residents in 2019 in an area of more than 105 km² (41 sq mi), making it the 30th most densely populated city in the world in 2020. S ...

, from which he graduated as an '' agrégé'' qualified in

physics Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which r ...

. Appointed at

Université Lille Nord de France The Community of Universities and Institutions (COMUE) Lille Nord de France (formerly Université Lille Nord de France) was a French Groups of Universities and Institutions ( COMUE) spread over multiple campuses and centered in Lille (North - Hauts ...

, he taught physics and electrical engineering at

École centrale de Lille Located in the campus of Science and Technology (Cité Scientifique) of the University of Lille in Villeneuve-d'Ascq ( European Metropolis of Lille - Hauts-de-France); École Centrale de Lille is a renowned graduate engineering school, with roots ...

from 1893 to 1895. In November 1900, he was appointed as head of the

Puy-de-Dôme Puy-de-Dôme (; oc, label=Auvergnat, lo Puèi de Doma or ''lo Puèi Domat'') is a department in the Auvergne-Rhône-Alpes region in the centre of France. In 2019, it had a population of 662,152.Auvergne Auvergne (; ; oc, label=Occitan, Auvèrnhe or ) is a former administrative region in central France, comprising the four departments of Allier, Puy-de-Dôme, Cantal and Haute-Loire. Since 1 January 2016, it has been part of the new region Auverg ...

region of

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, where he worked until his death in 1910. It was during his time at the observatory that he made the crucial observation that led to his discovery of geomagnetic reversal. In 1905, he found that rocks in an ancient lava flow at Pontfarin in the

commune A commune is an alternative term for an intentional community. Commune or comună or comune or other derivations may also refer to: Administrative-territorial entities * Commune (administrative division), a municipality or township ** Communes of ...

Cézens Cézens is a commune in the Cantal department in south-central France. Population See also *Communes of the Cantal department The following is a list of the 246 Communes of France, communes of the Cantal Departments of France, department o ...

(part of the

Cantal Cantal (; oc, Cantal or ) is a Departments of France, department in the Auvergne-Rhône-Alpes Regions of France, region of France, with its Prefectures in France, prefecture in Aurillac. Its other principal towns are Saint-Flour, Cantal, Saint ...

département In the administrative divisions of France, the department (french: département, ) is one of the three levels of government under the national level ("territorial collectivity, territorial collectivities"), between the regions of France, admin ...

'') were magnetised in a direction almost opposite to that of the present-day

magnetic field A magnetic field is a vector field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and to ...

. From this, he deduced that the

magnetic North Pole The north magnetic pole, also known as the magnetic north pole, is a point on the surface of Earth's Northern Hemisphere at which the planet's magnetic field points vertically downward (in other words, if a magnetic compass needle is allowed t ...

of the time was close to the current geographical

South Pole The South Pole, also known as the Geographic South Pole, Terrestrial South Pole or 90th Parallel South, is one of the two points where Earth's axis of rotation intersects its surface. It is the southernmost point on Earth and lies antipod ...

, which could only have happened if the magnetic field of the Earth had been reversed at some point in the past. He was correct, though it took another 50 years before his theory was fully accepted by the scientific community.

References

*
Bernard Brunhes, Directeur de l’Observatoire du Puy-de-Dôme (1900–1910)
, Observatoire de Physique du Globe de Clermont-Fd. {{DEFAULTSORT:Brunhes, Bernard 1867 births 1910 deaths École Normale Supérieure alumni French geophysicists Scientists from Toulouse