Geology 107: Homework Study Guide.

Geology 107: Homework Study Guide. The more silica in magma, the lower the viscosity. - CORRECT ANSWER False As a result of partial melting, magma originates in __________. - CORRECT ANSWER the mantle and crust When lava erupts at Earth's surface, what type of rock is produced? - CORRECT ANSWER extrusive Pyroclastic debris from a volcanic eruption can include _____. - CORRECT ANSWER ash and cinders Why does magma have a tendency to rise after its formation? - CORRECT ANSWER It is less dense than the surrounding rock. Most igneous rocks never reach the surface. However, igneous rocks other than those formed in volcanoes are found exposed on many parts of Earth. How do you account for this phenomenon? - CORRECT ANSWER They formed at depth and have been exposed by uplift and erosion. Based on the diagram shown in the video, name two minerals that are unlikely to coexist in the same igneous rock. - CORRECT ANSWER Quartz and muscovite Muscovite and pyroxene**** Na-plagioclase and amphiboles Quartz and feldspar Pyroxene and olivine