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Copyright © by Holt, Rinehart and Winston. All rights reserved.
Module F: Chapter 2
Rocks: Mineral Mixtures
Section 1: The Rock Cycle
Section 2: Igneous Rock
Section 3: Sedimentary Rock
Section 4: Metamorphic Rock
End of Slide
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 1
The Rock Cycle
Bellringer
Most of us work hard to recycle the items we use in our
daily life lives to minimize the pollution we cause. In a way
the earth also recycles, through the rock cycle. Can you
imagine what rock might look like through each stage of the
rock cycle? How long do you think it takes to recycle a
soda can? What about a piece of granite?
Record your thoughts in your science journal.
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 1
The Rock Cycle
Objectives
• Describe two ways rocks have been used by humans.
• Describe four processes that shape Earth’s features.
• Describe how each type of rock changes into another
type as it moves through the rock cycle.
• List two characteristics of rock that are used to help
classify it.
End of Slide
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 1
The Rock Cycle
The Value of Rock
• What Is Rock? Scientists define rock as a naturally
occurring solid mixture of crystals of one or more minerals.
• Why Is Rock Important? Rock has been an important
natural resource for as long as humans have existed. Early
humans used rock to make tools. Ancient and modern
civilizations have used rock as a construction material.
End of Slide
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 1
The Rock Cycle
Processes That Shape the Earth
• Weathering, Erosion, and Deposition Weathering,
erosion, and deposition are all processes that shape the
surface of the Earth.
• Heat and Pressure Sedimentary rock can form when
buried sediment is squeezed by the weight of overlying
layers of sediment. If the temperature and pressure are
high enough, the rock can change into metamorphic rock.
• How the Cycle Continues Buried rock is exposed at the
Earth’s surface by a combination of uplift and erosion. This
continues the rock cycle.
End of Slide
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 1
The Rock Cycle
Illustrating the Rock Cycle
• The Flow of Rock The rock cycle is the continual process
by which new rock forms from old rock material.
Round and Round It Goes
• Rolling Stones The sequence of events in the rock cycle
depends on processes, such as weathering, erosion,
deposition, pressure, and heat, that change the rock
material. Look at the illustrated rock cycle on the next slide
and identify what processes are taking place at each stage.
End of Slide
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 1
The Rock Cycle
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 1
The Rock Cycle
Rock Classification
• Composition The composition of a rock is determined by
the minerals that make up the rock.
• Texture The texture of a rock is determined by the size,
shape, and positions of the grains that make up the rock.
End of Slide
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 2
Igneous Rock
Bellringer
Do you think rocks that cooled and solidified from lava on
Earth’s surface would look different from those that cooled
and solidified from magma inside the Earth? Would you be
more likely to find igneous rock in the Rocky Mountains or
in the Hawaiian Islands?
Explain your answer in your science journal.
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 2
Igneous Rock
Objectives
• Describe three ways that igneous rock forms.
• Explain how the cooling rate of magma affects the texture
of igneous rock.
• Distinguish between igneous rock that cools within
Earth’s crust and igneous rock that cools at Earth’s surface.
End of Slide
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 2
Igneous Rock
Origins of Igneous Rock
• Formation Igneous rock forms when magma cools and
hardens.
Composition and Texture of Igneous Rock
• Appearance Determined by Cooling Rate Igneous
rocks can be composed of a wide variety of minerals. The
texture of igneous rock is determined by the rate at which
the rock cools.
End of Slide
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 2
Igneous Rock
Igneous Rock Formations
• Intrusive Igneous Rock When magma intrudes, or
pushes, into surrounding rock below the Earth’s surface
and cools, the rock that forms is called intrusive igneous
rock. Intrusive igneous rock usually has a coarse-grained
texture because it is well insulated by surrounding rock and
cools very slowly. Some intrusive igneous formations are
illustrated on the next slide.
• Extrusive Igneous Rock Igneous rock that forms from
magma that erupts,or extrudes, onto the Earth’s surface is
called extrusive igneous rock. Extrusive rock is common
End of Slide
around volcanoes.
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 2
Intrusive Igneous Rock Bodies
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 3
Sedimentary Rock
Bellringer
Tree rings are formed each year of a trees life cycle. Tree
rings exist because the weather changes of the seasons
are reflected in the trees bark as the tree grows.
Sedimentary rock is formed in layers over time much the
same way. Events like forest fires and droughts will be
visible in tree rings just as they are visible in sedimentary
rock layers. How are layers in sedimentary rock alike or
different from rings in a tree? What can geologists infer
from examining sedimentary rock layers?
Record your answers in your science journal.
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 3
Sedimentary Rock
Objectives
• Describe the origin of sedimentary rock.
• Describe the three main categories of sedimentary rock.
• Describe three types of sedimentary structures.
End of Slide
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 3
Sedimentary Rock
Origins of Sedimentary Rock
• How Sedimentary Rock Is Formed Through the process
of erosion, rock and mineral fragments, called sediment,
are moved from one place to another. Eventually, the
sediment is deposited in layers. The layers develop into a
natural cement that binds the rock and mineral fragments
together into sedimentary rock.
• Where Sedimentary Rock Is Formed Sedimentary rock
forms at or near the Earth’s surface.
End of Slide
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 3
Sedimentary Rock
Composition of Sedimentary Rock
• Clastic Sedimentary Rock Clastic sedimentary rock
forms when rock or mineral fragments are cemented
together.
• Chemical Sedimentary Rock Chemical sedimentary
rock forms from solutions of dissolved minerals and water.
• Organic Sedimentary Rock Organic limestone forms
from the remains of plants and animals.
End of Slide
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 3
Sedimentary Rock
Sedimentary Rock Structures
• Common Structures Sedimentary structures include
ripple marks, mud cracks, and rain-drop impressions.
• Stratification The most important feature of sedimentary
rock is stratification. Stratification is the process in which
sedimentary rocks are arranged in layers.
End of Slide
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 4
Metamorphic Rock
Bellringer
Write a brief description of how cookies are made. How is
the mixture of raw ingredients like sedimentary rock? Do
the raw ingredients of a cookie look the same after they are
done baking? Describe how cookie dough metamorphoses
when it is baked in an oven.
Record your responses in your science journal.
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 4
Metamorphic Rock
Objectives
• Describe two ways a rock can undergo metamorphism.
• Explain how the mineral composition of rocks changes as
the rocks undergo metamorphism.
• Describe the difference between foliated and nonfoliated
metamorphic rock.
• Explain how metamorphic rock structures are related to
deformation.
End of Slide
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 4
Metamorphic Rock
Origins of Metamorphic Rock
• Contact Metamorphism One way rock can undergo
metamorphism is by being heated by nearby magma.
When magma moves through the crust, the magma heats
the surrounding rock and changes it, causing contact
metamorphism.
• Regional Metamorphism When pressure builds up in
rock that is buried deep below other rock formations or
when large pieces of the Earth’s crust collide with each
other, regional metamorphism occurs.
End of Slide
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 4
Regional and Contact Metamorphism
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Section 4
Metamorphic Rock
Composition of Metamorphic Rock
• Changes in Composition As rocks undergo
metamorphism, the original minerals in a rock change into
new minerals that are more stable in new pressure and
temperature conditions.
• Index Minerals Many of these new minerals form only in
metamorphic rock. These minerals are known as index
minerals, and are used to estimate the temperature, depth,
and pressure at which a rock undergoes metamorphism.
End of Slide
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 4
Metamorphic Rock
Textures of Metamorphic Rock
• Foliated Metamorphic Rock Foliated metamorphic rock
has mineral crystals aligned in planes or bands.
• Nonfoliated Metamorphic Rock Nonfoliated rocks have
unaligned mineral crystals.
Metamorphic Rock Structures
• Deformation Metamorphic rock structures are caused by
deformation.
End of Slide
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 4
Rocks: Mineral Mixtures
Concept Map
Use the following terms to complete the concept map on
the next slide: clastic, exclusive, igneous, intrusive,
metamorphic, regional, rocks, sedimentary.
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 4
Concept Map
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 4
Concept Map
Copyright © by Holt, Rinehart and Winston. All rights reserved.