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Science 21 May 1971:
Vol. 172. no. 3985, pp. 840 - 845
DOI: 10.1126/science.172.3985.840
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Articles

Paleomagnetic Study of a Reversal of the Earth's Magnetic Field

J. R. Dunn 1, M. Fuller 1, H. Ito 1, and V. A. Schmidt 1

1 Department of Earth and Planetary Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania 15213

A detailed record of a field reversal has been obtained from the natural remanent magnetization of the Tatoosh intrusion in Mount Rainier National Park, Washington. The reversal took place at 14.7 ± 1 million years and is interpreted to be from reverse to normal. A decrease in the intensity of the field of about an order of magnitude occurs immediately before the reversal, while its orientation remains substantially unchanged. The onset of the reversal is marked by abrupt swinging of the virtual geomagnetic pole along an arc of a great circle. During the reversal the pole traces a path across the Pacific. In the last stage of the process recorded in the sections, the succession of virtual geomagnetic poles is very similar to those generated by secular variation in the recent past. Although the cooling rate of the intrusion is not sufficiently well known to permit a useful calculation of the duration of the reversal process, an estimate based on the length of the supposed secular variation cycles gives 1 to 4 x 103 years for the reversal of field direction and approximately 1 x 104 years for the time scale of the intensity changes.


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Paleomagnetic Record of a Geomagnetic Field Reversal from Late Miocene Mafic Intrusions, Southern Nevada.
C. D. Ratcliff, C. D. Ratcliff, J. W. Geissman, F. V. Perry, B. M. Crowe, and P. K. Zeitler (1994)
Science 266, 412-416
   Abstract »    PDF »
Polarity Transition Records and the Geomagnetic Dynamo.
K. A. Hoffman and K. A. HOFFMAN (1977)
Science 196, 1329-1332
   Abstract »    PDF »
PALAEOMAGNETISM: State of the Art, 1976.
(1977)
Journal of the Geological Society 133, 1-3
   Abstract »    PDF »


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