Earth’s Structure and Materials – Course 2
3-4 Igneous and Metamorphic Rock
3-5 Sedimentary Rocks
Vocabulary
Extrusive Rock- Igneous rock formed from lava that erupted onto
Earth’s surface. (Exit)
Intrusive Rock- Igneous rock that formed when magma hardened
beneath the surface of Earth. (Inside)
foliated rock
nonfoliated rock
Foliated- Metamorphic rocks that have their grains arranged either in
parallel layers or bands.
Nonfoliated- Metamorphic rocks that have their grains arranged
randomly.
Rock Dough
My Planet Diary pg. 114
Misconception: Rocks Do Not Change Form
Did you know that heat can change a rock’s form without melting it?
To understand how, think of what happens when you bake cookies.
You might mix flour, eggs, sugar, and baking powder in a bowl.
When you bake the raw dough in a hot oven, the dough changes into
cookies. Heat can change rock, too. If hot magma or lava come near
rock, the heat can “bake” the rock. The ingredients in the rock—the
minerals—might not melt. But the heat can still change the rock into
a new form!
Does rock have to melt in order to
Change form? Explain.
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How Do Geologists Classify Igneous Rocks? Pg. 114
Even though all igneous rocks form from magma or lava,
igneous rocks can look vastly different from each other.
Igneous rocks are classified by their :
1. Origin
2. Texture
3. Mineral Composition.
Ignis means “fire” in Latin. What is “fiery” about
igneous rocks???
Origin
Igneous rock may form on or beneath Earth’s surface.
Extrusive rock is igneous rock formed from lava that erupted
onto Earth’s surface.
•Basalt is the most common extrusive rock.
Igneous rock that formed when magma hardened beneath the
surface of Earth is called intrusive rock.
•The most abundant type of intrusive rock in continental crust is
granite.
Texture
The texture of an igneous rock depends on the size and shape of its
mineral crystals.
Rapidly cooling lava forms fine-grained igneous rocks with
small crystals or no crystals at all.
Extrusive rocks have a fine-grained or glassy texture
Extrusive fine grained
Intrusive Course grained
Slowly cooling magma forms coarse-grained rocks, such as
granite, with large crystals.
.
Intrusive rocks have larger grains than extrusive rocks.
Lava that is low in silica usually forms dark-colored rocks such as basalt. Magma
that is high in silica usually forms light-colored rocks, such as granite.
Igneous and Metamorphic Rock – pg. 115
Igneous Rock Origins and Textures
The texture of igneous rock varies according to its origin. Did the rocks in
the pictures form at A or B? Write your answers in the spaces provided.
Mineral Composition – pg. 116
Lava that is low in silica usually forms
dark-colored rocks such as basalt.
Magma that is high in silica usually forms
light-colored rocks, such as granite.
Uses of Igneous Rock pg. 116
People throughout history have used igneous rock for tools and
building materials.
Granite has been used to build statues, fortresses, bridges, and
public buildings.
Today, thin polished sheets of granite are used in curbstones and
floors.
 Basalt is used for cobblestones and as a
material in landscaping and roads.
Assess Your Understanding pg. 116
1a. Identify Rhyolite is an (Intrusive, Extrusive) igneous rock.
b. Summarize How does rhyolite form?
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c. Compare and Contrast Rhyolite has a similar composition to
granite. Why is the texture of rhyolite different from the texture of
granite?
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What are Metamorphic Rocks? – pg. 117
When great heat and pressure are applied to rock,
the rock can change both its
and its
Any rock that forms from another rock as a result
of changes in heat or pressure
(or both heat and pressure) is a.
How Metamorphic Rocks Form – pg. 117
Pockets of magma can rise through the crust. The high
temperatures of these pockets can change rock into
metamorphic rock.
Collisions between Earth’s plates can also push rock down
toward the heat of the mantle. Plate collisions cause great
pressure to be applied to rock while mountains are being formed.
The pressure can deform, or change the physical shape of, the
rock. Under very high temperature or pressure (or both), the
minerals in a rock can be changed into other minerals. The
appearance, texture and crystal structure of the minerals in the
rock change.
How Metamorphic Rocks are Classified-pg. 118
Geologists classify metamorphic rocks according to the
arrangement of the grains making up the rocks.
FOLIATED ROCKS
Metamorphic rocks that have their grains arranged either in
parallel layers or bands are said to be foliated.
 Foliated describes the thin, flat layering found in most
metamorphic rocks.
Crystals in granite can be flattened to create the foliated texture
of gneiss. Heat and pressure change the sedimentary rock shale
into slate. As shale changes into slate, the mineral composition
of the shale can change.
How Metamorphic Rocks Are Used- pg. 119
Some metamorphic rocks are
nonfoliated.
 The mineral grains in these rocks are arranged randomly.
 Marble and quartzite are metamorphic rocks that have a
nonfoliated texture. Quartzite forms out of quartz sandstone.
Marble usually forms when limestone is subjected to heat and
pressure deep beneath the surface. The metamorphic rocks
marble and slate are important materials for building and
sculpture.
Sedimentary Rocks 3-5
How Do Sedimentary Rocks Form?
What Are the Three Major Types of Sedimentary Rocks?
How Are Sedimentary Rocks Formed?
Vocabulary
Sediment- Small, solid pieces of material
that come from rocks or living things.
Weathering- the effects of freezing,
thawing, plant roots, acid and
other forces on rock that break
down the rock into fragments.
Erosion –process by which running
water, wind, or ice carry away the
fragments of broken-up rock.
Deposition- the process by which
sediment settles out of the
water or wind carrying it.
Sedimentary Rocks Vocabulary
Compaction- the process that
presses sediments together
Clastic Rock- a sedimentary rock
formed when rock fragments
are squeezed together.
Organic Rock- a sedimentary rock
formed with the remains of plants
and animals are deposited in layers.
Chemical Rock- a sedimentary rock that forms when minerals
dissolved in a water solution crystallize.
My Planet Diary pg. 120
The Cutting Edge
If you had to carve tools out of stone, would you know which
rocks to use? Dr. Beverly Chiarulli, an archaeologist at Indiana
University of Pennsylvania, studies stone tools that were used by
people in Pennsylvania 10,000 years ago. Dr. Chiarulli has found
that these people crafted spearheads out of the sedimentary
rocks called chert and jasper. Chert is hard and has a very fine
texture. It is brittle, but does not fracture along thin, even planes.
So, chert can be shaped somewhat easily by flaking off chips,
producing the sharp edges needed for spearheads.
What properties of chert allow it to be carved into sharp
spearheads? ________________________________________
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How Do Sedimentary Rocks Form? Pg. 120
Sediment is small, solid pieces of material that come from rocks or
living things.
Sedimentary rocks form when sediment is deposited
by water and wind.
Most sedimentary rocks are formed through a sequence of processes:
1. weathering
2. erosion
3. deposition
4. compaction
5. cementation.
How Do Sedimentary Rocks Form? Pg. 121
Rock on Earth’s surface is constantly broken up by
weathering—the effects of freezing and thawing, plant roots,
acid, and other forces on rock.
After the rock is broken up, the fragments are carried away as
a result of erosion—the process by which running water, wind,
or ice carry away bits of broken-up rock.
Deposition is the process by which sediment settles out of the
water or wind carrying it.
The process that presses sediments together is compaction.
Cementation is the process in which dissolved minerals
crystallize and glue particles of sediment together.
Sedimentary Rocks
WEDCC
How Sedimentary Rock Forms
Sedimentary rocks form through a
series of processes over millions of
years.
Sedimentary Rocks
What is the proper sequence of the terms in the
word bank that will show how mountains can
change into sedimentary rock?
Assess Your Understanding pg. 121
I get it! Now I know that most sedimentary rocks are formed
through the processes of
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What Are The Three Major Types Of
Sedimentary Rocks?
Geologists classify sedimentary rocks according to the type of sediments
that make up the rock. The
are:
Clastic
3 major groups of sedimentary rocks
rocks
chemical rocks
organic rocks
.
3 Major Types of Sedimentary Rocks – pg 122
A clastic rock is a sedimentary rock formed when rock
fragments are squeezed together. Some common clastic rocks
are shale, sandstone, conglomerate, and breccia.
Organic rock forms where the remains of plants and
animals are deposited in layers. Organic rocks include coal and
limestone.
Chemical rock forms when minerals dissolved in a water
solution crystallize. Chemical rocks include limestone and rock
salt.
Sedimentary Rocks pg. 123
Organic Rocks
How do coal and limestone form?
Apply It! Pg. 124
These rock “towers” in Mono Lake, California, are made of tufa, a
form of limestone. Tufa forms from water solutions that contain
dissolved materials. The towers formed under water. They became
exposed when the water level in the lake dropped as a result of water
needs for the city of Los Angeles.
1. Classify Tufa is a (clastic, organic, chemical) sedimentary rock.
2. Infer What mineral was dissolved in the waters of Mono Lake and
later crystallized to form the rock towers?
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3. Challenge When acid comes into contact with calcite, the acid
bubbles. How can geologists use acid to confirm that the rock towers
are made of limestone?
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Assess Your Understanding pg. 124
1a. Review Shale forms from tiny particles of (clay, sand, mica).
b. Describe How is clay deposited to form shale?
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c. Infer You come across a thick deposit of shale that forms a
layer in the ground. What can you infer about the area’s past
environment? _______________________________________
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How Are Sedimentary Rocks Used? Pg. 125
People have used sedimentary rocks throughout history for many
different purposes, including for tools and building materials.
Chert and flint were used to make spearheads and arrowheads.
Sandstone and limestone are used as building materials.
Limestone is used to make cement and steel.
Figure 4 Hurricane Monument (Islamorada, Florida)
Evaluate the design Do the benefits of constructing monuments
out of limestone outweigh the damage acid rain causes them?
Explain._____________________________________________
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____________________________________________________
Assess Your Understanding pg. 125
I get it! Now I know that throughout history, people have used
sedimentary rocks for
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The Rock Cycle
The Rock Cycle
Through melting,
weathering and erosion,
and heat and pressure, the
rock cycle constantly
changes rocks from one
type into another type.
The Rock Cycle
Patterns in the Rock
Cycle: Surface Events
All of the paths of the rock
cycle result from only a few
surface and subsurface
processes. What words
belong in the empty boxes
in the graphic organizer?
The Rock Cycle
Surface and Subsurface Events: the Tibetan Plateau
Processes on and underneath Earth’s surface drive the rock cycle in
mountains on the Tibetan Plateau.
The Rock Cycle
The Rock Cycle and Plate Tectonics
New rock forms on the ocean floor of the Atlantic Ocean, forming a ridge.
Here, two plates move apart.
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