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Volcanism

Volcanism. Dr. Bob Hickey Department of Geography and Land Studies Central Washington University. Flood Basalts. Flood Basalts. Very low viscosity, high volume. Basaltic (high Mg, Fe; low Si) Fill the low spots on a landscape, generally does not form a ‘volcano’

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Volcanism

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  1. Volcanism Dr. Bob Hickey Department of Geography and Land Studies Central Washington University

  2. Flood Basalts

  3. Flood Basalts • Very low viscosity, high volume. • Basaltic (high Mg, Fe; low Si) • Fill the low spots on a landscape, generally does not form a ‘volcano’ • Origin – continental hot spots • Deccan Plateau, India • Columbia Basin, USA

  4. Slides from Craters of the Moon

  5. Hawaii • Also basaltic • Low viscosity • Low explosivity. • Forms shield volcanoes • Low slope • From base to top, Mauna Loa is the highest mountain in the world.

  6. Mount St. Helens • Part of the Cascade Mountains in Washington State • Most recent major US volcanic eruption • Still active, with significant growth of the lava dome and occasional small eruptions (rebuilding the cone)

  7. Flood Basalts

  8. Show USGS slides • From 1980

  9. My first trip • Fall, 1988 • Geology Dept. Field trip. • Toured area and hiked up to the lava dome

  10. Second trip • Late Summer, 2003. • Hiked up to the mountain from Johnson Ridge

  11. Tree casts and lava tubes

  12. Akaroa (New Zealand)

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