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Unformatted text preview: Crystal Cozart ESC1000 September 29, 2009 Ch.8 Homework 5.) Granitic magma contains about 70% silica, whereas the silica content of basaltic magma is only about 50% silica. 7.) Magma rises soon after it forms because the magma is a lower density than the surrounding rock. Thus, it rises toward the surface immediately after it forms. 8.) Basaltic magma usually erupts in a relatively gentle manner onto Earth's surface from a volcano. In contrast, granitic magma typically solidifies within Earth's crust. When granitic magma does erupt onto the surface, it does so violently. These contrasts in behavior of the two types of magma are causes by differences in silica and water content. Because of its high silica content, granitic magma contains longer chains than does basaltic magma. The long chains become tangled, making magma stiff, or viscous. It rises slowly because of the viscosity and has ample time to solidify within the crust before reaching the surface. In contrast, basaltic magma is ample time to solidify within the crust before reaching the surface....
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This note was uploaded on 02/13/2011 for the course ESC 1000 taught by Professor Staff during the Fall '08 term at University of Florida.
- Fall '08