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Learning Objectives
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Chapter 4: Volcanism and Extrusive
Rocks
Rocks
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- How a lava's viscosity
controls eruptive violence
- How the silica content
of lava, presence of gases, and temperature of melt determine viscosity
- Identification and classification
of extrusive rocks based on mineral composition and texture
- How rate of cooling and
viscosity of magma or lava control grain size and texture of extrusive rocks
- Characteristic textures
of obsidian, pumice, scoria, tuff, and breccia; how porphyritic and vesicular
rocks are formed
- How shield volcanoes,
cinder cones, composite volcanoes, and volcanic domes develop; how plateau
basalts result from successive lava floods; characteristics of submarine eruptions
and pillow basalts
- Sources of lava and the
origin of magmas
- The global distribution
of volcanic activity: andesite volcanoes along the circum-Pacific and Mediterranean
belts; submarine volcanism on mid-oceanic ridges
- Basalt, the most abundant
extrusive rock, makes up a major part of the oceanic crust.
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