Chapter 4: Rocks
Lesson 1: Rocks and the Rock Cycle
Rocks
1. How do geologist benefit from studying rocks?
2. How is the composition of a rock related to the composition of the grains that make it up?
Texture
3. What is meant by the word “texture” as it applies to rocks?
4. How is texture used to classify different types of rocks?
Composition
5. How are rocks classified?
6. How do the types of minerals that a rock is made of provide clues to where the rock formed?
Three Major Rock Types
7. What is the main criterion scientists use to classify rocks?
8. What are the three major rock types?
Ingneous Rocks
9. How does igneous rocks form?
Sedimentary Rocks
10. What causes rocks exposed on Earth’s surface to break down?
11. Describe the building blocks of sedimentary rocks.
Metamorphic Rocks
12. Which environmental changes must happen for a rock to become metamorphosed?
13. What types of changes occur within a rock that has been metamorphosed?
The Rock Cycle
14. What is the rock cycle?
15. Is it possible for any type of rock to change into any other type of rock? Explain.
Rocks in Action
16. Explain how it’s possible for magma to become a metamorphic rock.
Lesson 2: Igneous Rocks
Igneous Rock Formation
17. How do igneous rocks form?
Extrusive Rock
18. How does extrusive rock form?
19. Why are there holes in igneous rocks?
Intrusive Rocks
20. Where do intrusive rocks form?
Igneous Rock Identification
Texture
21. What makes up an igneous rock’s texture?
Composition
22. How are extrusive and intrusive rocks different?
Lesson 3: Sedimentary Rocks
Sedimentary Rock Formation
23. What is the difference between compaction and cementation?
24. What are two ways that existing rock material can be transported to a new location?
Sedimentary Rock Identification
25. In which way are both igneous and sedimentary rocks classified?
Clastic Sedimentary Rocks
26. Why can’t sediment size alone be used to identify a sedimentary rock environment?
Chemical Sedimentary Rocks
27. How do chemical rocks form?
Biochemical Sedimentary Rocks
28. How do chemical and biochemical sedimentary rocks form?
Lesson 4: Metamorphic Rocks
Metamorphic Rock Formation
29. What is metamorphism?
Temperature and Pressure
30. Under what conditions do metamorphic rock form?
Metamorphic Rock Identification
31. How are the layers in metamorphic rocks different from the layers in sedimentary rocks?
Foliated Rocks
32. What type of metamorphic rock has layers?
Nonfoliated Rocks
33. How can you tell the difference between nonfoliated metamorphic rocks and intrusive igneous
rocks?
Contact and Regional Metamorphism
34. Compare and contrast contact metamorphism and regional metamorphism.
Chapter 4: Rocks Key
Lesson 1: Rocks and the Rock Cycle
Rocks
1. How do geologist benefit from studying rocks? They can better understand the way rocks form and
the ancient environments in which they formed.
2. How is the composition of a rock related to the composition of the grains that make it up? A rock’s
overall composition is determined by the types of grains that make up the rock.
Texture
3. What is meant by the word “texture” as it applies to rocks? A rock’s texture is determined by the
size of its grains and the way its grains fit together.
4. How is texture used to classify different types of rocks? The types of fragments that make up the
texture of a rock are clues to how the rock formed, so it is the basis for classifying rocks.
Composition
5. How are rocks classified? Rocks are classified based on texture and composition.
6. How do the types of minerals that a rock is made of provide clues to where the rock formed? Some
minerals form only under specific temperature and pressures. The temperature and pressure can
indicate where the rock formed.
Three Major Rock Types
7. What is the main criterion scientists use to classify rocks? Scientists classify rocks
according to they form.
8. What are the three major rock types? They are igneous, sedimentary, and metamorphic.
Ingneous Rocks
9. How does igneous rock form? Igneous rock forms when magma or lava cools and crystallizes.
Sedimentary Rocks
10. What causes rocks exposed on Earth’s surface to break down? Surface rocks are subjected
to the forces of wind, running water, ice, and gravity, which act to break them down into smaller pieces.
11. Describe the building blocks of sedimentary rocks. Sedimentary rocks are made mainly of
sediment. Sediment is the smaller pieces of rock that result when other rocks are broken down.
Metamorphic Rocks
12. Which environmental changes must happen for a rock to become metamorphosed? The rock
must be exposed to higher temperature, higher pressure, or the addition of chemical fluids.
13. What types of changes occur within a rock that has been metamorphosed? The rock’s
mineral composition and texture change.
The Rock Cycle
14. What is the rock cycle? The rock cycle is a series of processes that change one type of rock
into another type of rock.
15. Is it possible for any type of rock to change into any other type of rock? Explain. Yes, any
rock can turn into any of the other types of rock. For example, sedimentary rock can be heated until it
metamorphoses or until it melts to form magma. A metamorphic rock can be weathered and turn into
sediment that becomes sedimentary rock, or it can be heated until it is melted and then cool to form an
igneous rock.
Rocks in Action
16. Explain how it’s possible for magma to become a metamorphic rock. Magma can cool and
crystallize to form an igneous rock. The igneous rock can be deformed under intense heat and pressure
to form a metamorphic rock.
Lesson 2: Igneous Rocks
Igneous Rock Formation
17. How do igneous rocks form? Igneous rocks form from the cooling and crystallization of
molten rock above or below Earth’s surface.
Extrusive Rock
18. How does extrusive rock form? Extrusive rock forms when magma and other materials erupt
and solidify on Earth’s surface.
19. Why are there holes in igneous rocks? Holes in igneous rock form as gases excape from the
molten mixture during an eruption.
Intrusive Rocks
20. Where do intrusive rocks form? They form underground as magma cools.
Igneous Rock Identification
Texture
21. What makes up an igneous rock’s texture? Texture is made up of the sizes and arrangements
of the rock’s crystals.
Composition
22. How are extrusive and intrusive rocks different? Extrusive rocks result from cooling and
crystallization above ground. Intrusive igneous rocks form deep within Earth.
Lesson 3: Sedimentary Rocks
Sedimentary Rock Formation
23. What is the difference between compaction and cementation? Compaction occurs when
sediment is squeezed together by the weight of other sediment above it, and cementation occurs when
sediment is cemented together by dissolved minerals.
24. What are two ways that existing rock material can be transported to a new location? Two
ways that rock material can be transported include as dissolve material in water, and as fragments
carried by water, glacial ice, or wind.
Sedimentary Rock Identification
25. In which way are both igneous and sedimentary rocks classified? Both are classified
according to how they form.
Clastic Sedimentary Rocks
26. Why can’t sediment size alone be used to identify a sedimentary rock environment?
Sometimes the same rock environment can produce rocks with a variety of sediment sizes; also, the
shapes of the sediment offer clues about the rock environment.
Chemical Sedimentary Rocks
27. How do chemical rocks form? Chemical rocks form when water becomes saturated with
dissolved solids. As the water evaporates, the solids crystallize out of solution.
Biochemical Sedimentary Rocks
28. How do chemical and biochemical sedimentary rocks form? Chemical sedimentary rocks form
when minerals crystallize out of solution in water, and biochemical sedimentary rocks form from the
action of organisms in water.
Lesson 4: Metamorphic Rocks
Metamorphic Rock Formation
29. What is metamorphism? It is any process that affects the structure or composition of a
rock in a solid state as a result of changes in temperature, pressure, or the addition of chemical fluids.
Temperature and Pressure
30. Under what conditions do metamorphic rocks form? Metamorphic rocks can form due to
changes in temperature and pressure.
Metamorphic Rock Identification
31. How are the layers in metamorphic rocks different from the layers in sedimentary rocks? In
metamorphic rocks, the layers are made up of different kinds of mineral crystals.
Foliated Rocks
32. What type of metamorphic rock has layers? Foliated metamorphic rock has layers.
Non-foliated Rocks
33. How can you tell the difference between non-foliated metamorphic rocks and intrusive
igneous rocks? Intrusive igneous rocks usually consist of mineral grains that have different colors, while
non-foliated metamorphic rocks usually consist of mineral grains that are all the same color.
Contact and Regional Metamorphism
34. Compare and contrast contact metamorphism and regional metamorphism. Contact
metamorphism occurs where magma comes in contact with parent rock. Regional metamorphism occurs
over a much larger area and results from increases in pressure and temperature and chemical fluids.