Field Trip: Valles Caldera
The rhyolitic domes of Valles Caldera -- sampled near Jaramillo Creek -- were used by Doell and Dalrymple (1966) to document the termination of a newly-discovered polarity subchron:  the Jaramillo event.  This work helped lead to the widespread acceptance of the Vine-Matthews-Morley hypothesis of seafloor spreading, by establishing a magnetic polarity timescale consistent with the marine magnetic anomaly observations.  Although subsequent work has shown that the lavas actually record a later event (Singer and Brown, 2002), Valles Caldera is still where it all began.
Field trip will be led by John Geissman (University of New Mexico).  We will depart Thursday morning, prior to the meeting, returning mid-afternoon.  Field boots and rock hammers are not required, but cameras, sunglasses and hats are strongly recommended.
Field trip is now full.  Field trip registrations no longer being accepted.
Doell, R.R., and G.B. Dalrymple, Geomagnetic plarity epochs: a new polarity event and the age of the Brunhes-Matuyama boundary, Science, 152, 1060-1061, 1966.
Singer, B., and L.L. Brown, Santa Rosa Event: 40Ar/39Ar and paleomagnetic results from the Valles rhyolite near Jaramillo Creek, Jemez Mountains, New Mexico, Earth Planet. Sci. Lett., 197, 51-64, 2002.