19 Issues in Earth Science Education
Friday, 9 March 2012
1:30 PM - 5:00 PM
Espino A & B
PAISANO PASS DRIVE-THROUGH VOLCANO - A UNIQUE EARTH SCIENCE EDUCATIONAL RESOURCE
Paper number: 19-4
Program: Theme Sessions
Time: 2:15 PM – 2:30 PM
Authors
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Patricia W. DickersonUniversity of Texas at Austin, Austin, TX
Abstract
Development Of The Paisano Volcano (abridged): 35 million years ago basaltic lavas erupted out of a molten body of rock called a pluton, with a temperature of perhaps 2000 °F, approximately 5 miles in diameter, that rose slowly from deep within the mantle of the earth and lodged in hard crust 2 to 3 miles below the surface where you stand. Explosive pyroclastic eruptions driven by steam and carbon dioxide followed, and then more lava flows. After a quiet period pyroclastic flows began to erupt again, and then a caldera crater collapsed during violent explosions that partially emptied a magma chamber under the volcano. Finally more lavas erupted, followed by late mafic dikes and plugs, and much younger nepheline syenite, that intruded into the older volcanic strata. Development of the broad shield complex was completed in from 1 to 2 million years. Weathering and erosion continue to carve the different types of igneous rock into the colorful cliffs and wide valleys that you see in Paisano Pass today.