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Clerical:
We're wrapping up Earth Science Week! Rock your world!!!
Last chance to sign up a team for the FHSU Geosciences Scavenger Hunt 2010! Don't blow this Extra Credit opportunity!
Quizzes 9-12 are posted.
Homeworks #7 and #8 are posted. Homework #8 will be completed in class Friday (10/22/10).
Themes of the Day:
- Forms of Intrusive Igneous Bodies
- Types of Volcanoes
Forms of Igneous Bodies
- Intrusive forms:
- Extrusive forms:
Types of Volcanoes
- Profile of a volcano, and types of eruption dictated by composition of the magma (lava) - Types of Igneous Rocks
- Main types of volcanoes and volcanic products:
- Shield Volcanoes - low viscosity basaltic magmas - lava lakes and flows common - not explosive - flood basalts and submarine pillow lavas are basaltic, too - e.g., Mauna Loa, Hawaii
- Cinder Cones - variable composition, often basaltic - usually a single batch of magma - steep cones formed by cinders piled around vent at angle of repose - e.g., Paricutin, Mexico, Wizard Island, Crater Lake, Oregon
- Composite Volcanoes (Stratovolcanoes) - interayered lava flows and pyroclastic deposits - ranges from intermediate to felsic in composition (andesite-dacite-rhyolite) - in volcanic arcs above subduction zones - e.g., Mount Cleveland, Alaska
- Dome Volcanoes - similar in composition and often genetically related to composite volcanoes - usually more viscous (more silicic) magma type (dacite/rhyolite) - pyroclastic flows abundant - explosive eruptions common
- Continantal Calderas - in continental regions the result of the largest types of volcanic eruptions - large, shallow, silicic magma chambers empty catastrophically with unparalleled violence; roof of magma chamber collapses into emptied portion of magma chamber
- Difference in Scale
- Crater vs. Caldera
- USGS Photo Glossary of Volcanic Terms - lots of good illustrations of volcanoes and volcanic features
Virtual Volcanic Field Trip (time permitting)
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