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| Student Center |
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Chapter 3: Igneous Rocks, Intrusive Activity, and the Origin of Igneous Rocks
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Chapters 3 and 4 are about igneous rocks and igneous processes. (Either chapter may be read first.) Chapter 4 focuses on volcanoes and igneous activity that takes place at the earth's surface. Chapter 3 describes igneous processes that take place underground. However, you will learn early in this chapter how volcanic as well as intrusive rocks are classified based on their grain size and mineral content. The chapter continues with an explanation of the structural relationships between bodies of intrusive rock and other rocks in the earth's crust. This is followed by a discussion of how magmas form and are altered. We conclude by discussing various hypotheses that relate igneous activity to plate tectonic theory. 
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