Replies

Some unanswered questions [This Dynamic Earth, USGS] [6/22/2007]

EiU, p 146 (and referred to on p 202):
The observation was made on clay fired in kilns by the Etruscans and Greeks. The position of the ancient vases during firing is known. They were fired in a standing position, as the flow of the glaze testifies. The magnetic inclination or the magnetic dip of the iron particles in the fired clay indicates which was the nearest magnetic pole, the south or the north.

In 1896 Giuseppe Folgheraiter began his careful studies of Attic (Greek) and Etruscan vases of various centuries, starting with the eighth century before the present era. His conclusion was that in the eighth century the earth's magnetic field was inverted in Italy and Greece. Italy and Greece were closer to the south than to the north magnetic pole.

P.L. Mercanton of Geneva, studying the pots of the Hallstatt age from Bavaria (about the year -1000) and from the Bronze Age caves in the neighborhood of Lake Neuchatel, came to the conclusion that about the tenth century before the present era the direction of the magnetic field differed only a little from its direction today, and yet his material was of an earlier date than the Greek and Etruscan vases examined by Folgheraiter. But checking on the method and the results from Folgheraiter, Mercanton found them perfect.

An ancient vase found by F.A. Forel in Boiron de Morges, on Lake Geneva, was broken and its pieces were scattered and lay in all directions; when assembled, they all showed one and the same magnetic orientation, which proves again that the magnetic field of the earth was unable to change the orientation originally acquired by the clay when fired and cooled in the kiln.
Pole flips tied to plate tectonics [11/26/2011]

Large changes of the earth's magnetic fields in historical times
by William R. Corliss
Science Frontiers #22: Jul-Aug 1982
By measuring the magnetic properties of bricks and other accurately dated human artifacts, geophysicists can reconstruct the history of the local magnetic field. Near Loyang, China, the field was as much as 54% higher in 300 A.D. than it is now. It was 15% higher in 1500 A.D. In 1000, it was less than today's value.

(Wei, Q.Y., et al; "Intensity of the Geomagnetic Field near Loyang, China, between 500 BC and AD 1900," Nature, 296:728, 1982.)

Comment. Direct measurements of the earth's field go back only a few hundred years, but they are consistent with the data reconstructed from artifacts, both showing a steady decrease since 1500. No one has estimated the effects of these substantial changes on radiocarbon dating and, perhaps, human biology.
Pole flips tied to plate tectonics [11/26/2011]

"Earth In Upheaval", Immanuel Velikovsky, p 133
Most interesting is the discovery that the last time the reversal of the magnetic field took place was in the eighth century before the present era, or twenty-seven centuries ago. The observation was made on clay fired in kilns by the Etruscans and Greeks.

The position of the ancient vases during firing is known. They were fired in a standing position, as the flow of the glaze testifies. The magnetic inclination or the magnetic dip of the iron particles in the fired clay indicates which was the nearest magnetic pole, the south or the north.

In 1896 Giuseppe Folgheraiter began his careful studies of Attic (Greek) and Etruscan vases of various centuries, starting with the eighth century before the present era. His conclusion was that in the eighth century the earth's magnetic field was inverted in Italy and Greece. 7 Italy and Greece were closer to the south than to the north magnetic pole.

P. L. Mercanton of Geneva, studying the pots of the Hallstatt age from Bavaria (about the year 1000) and from the Bronze Age caves in the neighborhood of Lake Neuchatel, came to the conclusion that about the tenth century before the present era the direction of the magnetic field differed only a little from its direction today, and yet his material was of an earlier date than the Greek and Etruscan vases examined by Folgheraiter. But checking on the method and the results of Folgheraiter, Mercanton found them perfect.

An ancient vase found by F. A. Forel in Boiron de Morges, on Lake Geneva, was broken and its pieces were scattered and lay in all directions; when assembled, they all showed one and the same magnetic orientation, which proves again that the magnetic field of the earth was unable to change the orientation originally acquired by the clay when fired and cooled in the kiln. 8

These researches, continued and described in a series of papers by Professor Mercanton, presently with the Service Meteorologique Universitaire in Lausanne, show that the magnetic field of the earth, not very different from what it is today, was disturbed sometime during or immediately following the eighth century to the extent of complete reversal.

[footnotes]

7 G. Folgheraiter in Rendi Conti del Licet, 1896, 1899; Archives des sciences physiques ei naturelles (Geneva). 1899; Journal de physique, 1899; P. L. Mercanton, "La m&hode de Folgheraiter et son r61e en geophysique," Archives des sciences physiques et naturelles. 1907.

8 Bulletin de la Societe Vaudoise des sciences naturelles, Stance du 15 decembre 1909.

9 Manley speaks of "the possibility of its [earth's magnetic field] reversal in historical times, 2500 years ago, to be cleared up by more research." However, the more exact date is, according to the original works of Folgheraiter and Mercanton, the eighth century before the present era, or shortly thereafter.