Geomagnetic Polarity Epochs: A New Polarity Event and the Age of the Brunhes-Matuyama Boundary

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Science  20 May 1966:
Vol. 152, Issue 3725, pp. 1060-1061
DOI: 10.1126/science.152.3725.1060


Recent paleomagnetic-radiometric data from six rhyolite domes in the Valles Caldera, New Mexico, indicate that the last change in polarity of the earth's magnetic field from reversed to normal (the Brunhes-Matuyama boundary) occurred at about 0.7 million years ago. A previously undiscovered geomagnetic polarity event, herein named the "Jaramillo normal event," occurred about 0.9 million years ago.