Review Questions for Program #9: Metamorphic Rocks
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Program #9. If you are unsure of an answer, give your best
intelligent guess.
1. What is metamorphism?
The effects of heat (not enough to melt rocks) and pressure on rocks.
2. What information can be found in metamorphic rocks?
Conditions of heat and pressure, the age of the rocks
3. What is a protolith? What is an example of a protolith?
A protolith is a parent rock in metamorphism; what the rock is before it undergoes metamorphism. Limestone is a protolith for marble.
4. What is the depth range for most metamorphism? What is the range of temperatures of most metamorphism?
2 to 10 km and more; 200-800 degrees C
5. What is foliation? How does it form?
Foliation is the layering of minerals in metamorphic rocks that forms in response to pressure.
6. What is the difference between limestone and marble?
Contact metamorphism recrystallizes the calcite in limestone so that the grains are coarser and interlocking.
7. What are migmatites?
Metamorphic rocks that experience such a high degree of metamorphism that they almost begin to melt. Migmatites often have gneissic-like layering, but the layering is often very folded.
8. What are the two types of metamorphism? Where does each type form?
Regional metamorphism - high pressure, high
temperature
metamorphism that generally occurs at the base of mountain chains or at
convergent plate boundaries.
Contact metamorphism - high temperature
metamorphism
that generally occurs when magma chambers intrude and come into contact
with layers of sedimentary rock, baking them in the process.
9. How can minerals indicate metamorphic temperatures and pressures?
Certain minerals form only at certain temperatures and pressures. For instance, graphite forms at lower pressures than does diamond, which forms at high pressures.
10. What is metamorphic grade?
The degree or intensity of metamorphism; a high metamorphic grade implies high pressure and/or heat.
11. What are some examples of foliation?
slatey cleavage, schistose layering, gneissic layering
12. What are some examples of contact metamorphosed rocks?
marble, quartzite