Lesson 4 Reading Guide - KC

• How do metamorphic rocks form?• How do types of metamorphic rock

differ?

Metamorphic Rocks

• metamorphism• plastic

deformation• foliated rock

Metamorphic Rocks

• nonfoliated rock• contact

metamorphism• regional

metamorphism

• Metamorphism 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.

• Most metamorphic rocks form deep within Earth’s crust.

• Like igneous rock, metamorphic rocks form under high temperature and pressure conditions.

Metamorphic Rock Formation

• Plastic deformation is the permanent change in the shape of rock by bending and folding.

• Plastic deformation occurs during uplift events when tectonic plates collide and form mountains.

Metamorphic Rock Formation (cont.)

• The rock that changes during metamorphism is called the parent rock.

• The temperatures required to metamorphose rock depend on the parent rock’s composition.

Metamorphic Rock Formation (cont.)

Both temperature and pressure increase with depth in Earth’s crust and mantle.

Metamorphic Rock Formation (cont.)

Under what conditions do metamorphic rocks form?

Metamorphic rocks are classified into two groups based on texture: foliated rocks and nonfoliated rocks.

• Foliated rocks contain parallel layers of flat and elongated minerals.

• Metamorphic rocks that have mineral grains with a random, interlocking texture are nonfoliated rocks.

Metamorphic Rock Identification

Metamorphic Rock Identification (cont.)

foliatefrom Latin foliatus, means “consisting of thin, leaf-like layers”

• During contact metamorphism, magma comes in contact with existing rock, and its thermal energy and gases interact with the surrounding rock and forms nonfoliated metamorphic rock.

• Regional metamorphism is the formation of metamorphic rock bodies that are hundreds of square kilometers in size.

Metamorphic Rock Identification (cont.)

Metamorphic Rock Identification (cont.)

Compare and contrast contact metamorphism and regional metamorphism.

• Foliated metamorphic rocks have distinct layers of flat and elongated minerals.

• A nonfoliated metamorphic rock has minerals arranged in a random, interlocking texture.

• Contact metamorphism occurs when rocks come in contact with magma without melting.

A. metamorphism B. foliationC. plastic deformationD. rock deformation

When rocks bend or fold without melting, the permanent change in the rock’s shape is called what?

A. foliated rocksB. metamorphic rocksC. crystallized rocksD. nonfoliated rocks

What kind of rocks contain parallel layers of flat and elongated minerals?

A. regional C. plastic

B. crystal D. contact

Which type of metamorphism occurs when magma comes in contact with existing rock, and its thermal energy and gases interact with the surrounding rock?

7. With the right pressure and temperature conditions, minerals in a rock can change shape without breaking or melting.

8. Metamorphic rocks have layers that form as minerals melt and then recrystallize.

Do you agree or disagree?

Key Concept SummaryInteractive Concept MapChapter ReviewStandardized Test Practice

• Igneous rocks form from molten rock that cools and crystallizes.

• Sedimentary rocks form from compaction and cementation of sediments or evaporation and crystallization of minerals dissolved in water.

• Metamorphic rocks form from exposure of existing rocks to high pressures, temperatures, or the addition of chemical fluids.

• There are three major rock types—igneous, sedimentary, and metamorphic. Geologists study rock texture and mineral composition to identify rocks of each type.

• Rocks can melt or recrystallize. Rocks exposed on Earth’s surface can break down due to forces such as water, ice, wind, and gravity. New rocks form under changing temperature and pressure conditions or the addition of chemical fluids.

Lesson 1: Rocks and the Rock CycleN

ancy Sim

merm

an/Getty Im

ages

Lesson 2: Igneous Rocks• Igneous rocks form when volcanic material cools

and crystallizes.• Crystal size is dependent on how quickly the

magma or lava cools.• Igneous rocks range in color from light to dark,

depending on their mineral composition.

• Weathering, erosion, transportation, deposition, compaction, cementation, and crystallization are the important processes in the formation of sedimentary rocks.

• A sedimentary rock’s texture and mineral composition depends on where it formed and the forces that created it.

Lesson 3: Sedimentary Rocks

National Geographic/Getty Images

• Metamorphic rocks form from a parent rock that has been exposed to increases in temperature, pressure, or the addition of chemical fluids.

• Some metamorphic rocks have foliated textures and are deformed. Others are composed of coarse and blocky crystals that are uniform in color.

Lesson 4: Metamorphic Rocks

A. metamorphoses B. sediment deposit C. rock cycleD. rock deposit

Which term refers to the series of processes that change one type of rock into another type of rock?

A. size C. weight

B. colorD. texture

Geologists can determine if an igneous rock is extrusive or intrusive by studying its composition and which of these?

A. chemical C. carbonate

B. biochemical D. clastic

Which type of rock is sedimentary rock that was formed by organisms or contains the remains of organisms?

A. cementationB. compactionC. crystallizationD. erosion

Which process occurs when minerals dissolved in water crystallize between sediment grains?

A. igneous B. foliatedC. nonfoliatedD. sedimentary

Which type of rocks contain parallel layers of flat and elongated minerals?

A. sediment B. metamorphic rockC. lavaD. crystals

Which term refers to magma that erupts on Earth’s surface?

A. igneous B. sedimentary C. metamorphicD. mineral

When magma or lava cools and crystallizes, it creates which type of rock?

A. mineralsB. crystalsC. holesD. grains

An igneous rock is classified as extrusive if which part is difficult or impossible to see without a magnifying glass?

A. chemical reactionB. plastic deformationC. foliationD. metamorphism

Which term refers to any process that affects the structure or composition of solid rock?

A. cementationB. regional metamorphismC. contact metamorphismD. plastic deformation

Which process refers to the formation of metamorphic rock bodies that are hundreds of square kilometers in size?