1. Section 3: Metamorphic Rocks
Metamorphic rocks form when preexisting rocks are exposed to increases in temperature and pressure and to hydrothermal solutions. K
What I Know W
What I Want to Find Out L
What I Learned

2. Essential Questions
What are the different types and causes of metamorphism?
How are metamorphic textures described?
How do mineral and compositional changes occur during metamorphism?
How are rocks classified using the rock cycle?
Metamorphic Rocks
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3. Vocabulary Review New intrusive foliated nonfoliated
regional metamorphism
contact metamorphism
hydrothermal metamorphism
rock cycle
Metamorphic Rocks
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4. Recognizing Metamorphic Rock
When high temperature and pressure combine and change the texture, mineral composition, or chemical composition of a rock without melting it, a metamorphic rock forms.
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Metamorphic Rocks

5. Recognizing Metamorphic Rock
The high temperatures required for metamorphism are ultimately derived from Earth’s heat, either through deep burial or from nearby igneous intrusions.
The high pressures required for metamorphism come from deep burial or from compression during mountain building.
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Metamorphic Rocks

6. Recognizing Metamorphic Rock
Metamorphic minerals
During metamorphism, the minerals in a rock undergo solid-state alterations, which means that they change into new minerals that are stable under the new temperature and pressure conditions.
Metamorphic Rocks
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7. Recognizing Metamorphic Rock
Metamorphic textures
Foliated metamorphic rocks are characterized by layers and bands of minerals caused by high pressure during metamorphism.
Foliation develops when pressure is applied from opposite directions. The foliation develops perpendicular to the pressure direction.
Metamorphic Rocks
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8. Recognizing Metamorphic Rock
Metamorphic textures
Nonfoliated metamorphic rocks are composed mainly of minerals that form with blocky crystal shapes.
Metamorphic Rocks
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9. Recognizing Metamorphic Rock
Metamorphic textures
Increasing grain size parallels changes in composition and development of foliation. Grain size is not a factor in nonfoliated rocks.
Metamorphic Rocks
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10. Grades of Metamorphism
Different combinations of temperature and pressure result in different grades of metamorphism.
Each of the grades—low, intermediate, and high—is associated with a different suite of minerals and textures.
Metamorphic Rocks
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11. Grades of Metamorphism
Metamorphism of shale results in the formation of minerals that provide the wide variety of color observed in slate.
Metamorphic Rocks
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12. Types of Metamorphism Regional metamorphism
When high temperature and pressure affect large regions of Earth’s crust, they produce large belts of regional metamorphism, ranging from low grade to high grade.
Regional metamorphism results in changes in minerals and rock types, plus folding and deforming of the rock layers that make up the area.
Metamorphic Rocks
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13. Types of Metamorphism Contact metamorphism
When molten material, such as that in an igneous intrusion, comes in contact with solid rock, a local effect called contact metamorphism occurs.
High temperatures and moderate-to-low pressure form mineral assemblages that are characteristic of contact metamorphism.
Metamorphic Rocks
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14. Types of Metamorphism Hydrothermal metamorphism
When very hot water reacts with rock and alters its chemical and mineral composition, hydrothermal metamorphism occurs.
Chemical changes are common during contact metamorphism near igneous intrusions and active volcanoes.
Metamorphic Rocks
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15. Economic Importance of Metamorphic Rocks and Minerals
Many of the economic mineral resources that make the modern way of life possible are produced by metamorphic processes.
Metamorphic Rocks
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16. Economic Importance of Metamorphic Rocks and Minerals
Metallic mineral resources
Although deposits of pure metals are occasionally discovered, many metallic deposits are precipitated from hydrothermal solutions.
Metamorphic Rocks
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17. Economic Importance of Metamorphic Rocks and Minerals
Nonmetallic mineral resources
Many nonmetallic resources are also produced by metamorphism, including talc, asbestos, and graphite.
Metamorphic Rocks
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18. The Rock Cycle
The three types of rock are grouped according to how they form.
Igneous rocks crystallize from magma; sedimentary rocks form from cemented or precipitated sediments; and metamorphic rocks form from changes in temperature and pressure.
Metamorphic Rocks
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19. The Rock Cycle
Any rock can be changed into any other type of rock. This continuous changing and remaking of rocks is called the rock cycle.
The rock cycle shows some of the series of changes rocks undergo above and beneath Earth’s surface.
Metamorphic Rocks
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20. Add link to Animation from ConnectED here.
Types of Rocks
BrainPOP
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Add link to Animation from ConnectED here.
Metamorphic Rocks
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21. Review Essential Questions Vocabulary
What are the different types and causes of metamorphism?
How are metamorphic textures described?
How do mineral and compositional changes occur during metamorphism?
How are rocks classified using the rock cycle?
Vocabulary
foliated
nonfoliated
regional metamorphism
contact metamorphism
hydrothermal metamorphism
rock cycle
Metamorphic Rocks
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