Download Volcanoes Review Key

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Volcanoes Review
1. What are the two different types of magma? felsic and mafic
2. What determines the rate at which magma moves? the silica content
3. Describe felsic magma in terms of the following:
a. chemical composition: rich in silica minerals like quartz and feldspar
b. speed: slow-moving
c. type of volcanic eruptions: explosive
4. Describe mafic magma in terms of the following:
a. chemical composition: low silica; rich in Fe, Mg, Ca
b. speed: flows easily
c. type of volcanic eruptions: shield volcanoes
5. Solid fragments of lava are called tephra. List the different types of these
fragments in order from smallest to largest. Ash, lapilli, blocks, bombs
6. Find the following information for rift eruptions:
a. type of magma: mafic, basaltic
b. type of plate boundary: divergent
c. type of mountains: volcanic (shield)
7. Find the following information for subduction boundary:
a. type of magma: felsic
b. location of volcanic mountains for ocean-ocean subduction boundaries:
volcanic islands (island arc) on overriding plate
c. location of volcanic mountains for ocean-continent subduction boundaries:
volcanic mountains on the continental plate
8. Find the following information for hot spot eruptions:
a. type of magma: mafic, basaltic
b. type of mountain: volcanic (shield)
c. relationship between hotspot and lithospheric plate: lithospheric plate moves
over the hotspot
9. A result of volcanism is the formation of rock masses within other rocks. Another
name for these igneous intrusions is plutons.
10. Use the crustal block diagram below to identify some igneous intrusions.
dike
laccolith
sill
batholith