title: Geomagnetic polarity epochs: a new polarity event and the age of the brunhes-matuyama boundary.
abstract: 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.
authors.forename: R R
authors.initials: RR
authors.lastname: Doell
authors.forename: G B
authors.initials: GB
authors.lastname: Dalrymple