Rocks and Rock Cycle

Rocks and Rock Cycle

Middle School

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Learning Objectives

• Model the rock cycle, including melting, crystallization, weathering, and sedimentation processes.

• Explain how energy from the sun and Earth's interior drives the rock cycle.

• Identify the three main rock types and describe how they are formed.

• Connect energy flow and matter cycling to changes in rocks over geologic time.

Key Vocabulary

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Rock Cycle

The model describing how rocks change from one type to another over a long period.

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Weathering

The breakdown of rock at the Earth's surface by physical or chemical means like wind or rain.

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Igneous Rock

A type of rock that is formed from the cooling and crystallization of molten rock or magma.

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Sedimentary Rock

A type of rock formed from compacted and cemented sediment that builds up over time.

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Metamorphic Rock

A type of rock changed by extreme heat, pressure, or chemical reactions without melting completely.

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Plate Tectonics

The theory describing how Earth's large continental plates move and glide over the mantle, driving changes.

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The Rock Cycle: A Model of Matter and Energy

• The rock cycle shows how matter cycles through different forms on Earth.

• ​It is a slow process that changes rocks from one type to another.

• Energy from the sun and Earth’s interior powers all these transformations.

• These changes happen over geologic time, which can be millions of years.

Multiple Choice

What are the two main energy sources that drive the transformations in the rock cycle?

• Energy from the sun and Earth's interior

• Energy from the moon and the Earth's rotation

• Energy from wind and water

• Energy from geologic time and matter cycling

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How Are Igneous Rocks Formed?

• Intense heat inside Earth melts solid rock, creating hot liquid magma.

• As magma cools, its atoms arrange into orderly solid structures called crystals.

• This process of melting and crystallization results in the formation of igneous rocks.

• Slow cooling creates large crystals, while fast cooling results in small crystals.

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Multiple Choice

How does the cooling speed of magma affect the crystals in an igneous rock?

• How fast the magma cools determines how large the rock's crystals will be.

• The cooling speed only affects the color of the rock, not the crystals.

• Faster cooling creates larger crystals, while slower cooling creates smaller ones.

• Magma must cool at a specific speed to form any crystals at all.

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How Solar Energy Helps Form Sedimentary Rocks

• The sun's energy drives weather patterns like wind and rain on Earth.

• ​This weather causes weathering, breaking rocks into smaller pieces called sediment.

• Erosion by wind and water carries this sediment to a new place.

• Layers of sediment form new sedimentary rock over millions of years.

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Multiple Choice

What is the correct sequence of processes that form sedimentary rock?

• Weathering, then Erosion, then Sedimentation

• Erosion, then Weathering, then Sedimentation

• Sedimentation, then Weathering, then Erosion

• Erosion, then Sedimentation, then Weathering

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Earth's Internal Energy Reshapes Rocks

Deformation

• ​Immense pressure from inside the Earth can bend, fold, or break rocks.

• ​​This process, which changes a rock's original shape, is called deformation.

• ​It often occurs where tectonic plates collide, leading to the formation of mountains.

Metamorphism

• ​Intense heat and pressure deep inside the Earth change a rock's minerals.

• ​​This physical and chemical transformation happens without the rock actually melting.

• ​For example, sedimentary limestone can transform into the metamorphic rock called marble.

Multiple Choice

What is the main difference between rock deformation and metamorphism?

• Deformation changes a rock's shape, while metamorphism changes its mineral composition.

• Deformation is caused by heat, while metamorphism is caused by pressure.

• Deformation melts the rock completely, while metamorphism only breaks it.

• Deformation creates new rock, while metamorphism destroys it.

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Connecting the Processes: Plate Tectonics

• Plate tectonics connects all processes of the rock cycle.

• Convection currents in the mantle, powered by Earth's heat, move the plates.

• When plates collide, pressure can create mountains and metamorphic rocks.

• A subducting plate can melt into magma, forming new igneous rock.

Multiple Choice

According to the theory of plate tectonics, what happens when a tectonic plate subducts underneath another?

• The plate will melt into magma, which can then form new igneous rock.

• The plate will be folded and compressed to form metamorphic rock on the surface.

• A large mountain range will always form from the subducting plate material.

• The convection currents in the mantle will stop moving.

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Common Misconceptions

Misconception	Correction
Rocks are permanent and do not change.	The rock cycle is a continuous, slow process that changes rocks.
The rock cycle follows a single, circular path.	Any rock type can transform into any other type.
Rock formation happens quickly.	Rock formation is a very slow process, taking millions of years.
Surface and interior processes are separate.	Internal energy and solar energy are interconnected and drive the cycle.

Multiple Choice

How is the formation of sedimentary rocks dependent on the sun's energy?

• The sun's energy drives weather, which causes weathering and erosion, creating sediment.

• The sun's heat directly melts rocks into sediment.

• The sun's gravity pulls sediment together to form rock layers.

• The sun's energy is only involved in forming igneous rocks.

Multiple Choice

Why does magma that cools slowly beneath the Earth's surface create rocks with large crystals?

• The atoms have more time to arrange themselves into large, orderly patterns.

• The intense pressure beneath the surface squeezes the crystals, making them larger.

• Slow cooling traps more gases, which expand the crystals.

• Only fast-cooling magma can form large crystals.

Multiple Choice

A geologist discovers a mountain range composed primarily of marble, a metamorphic rock. What geological processes most likely occurred to form this range?

• Tectonic plates collided, subjecting existing limestone to intense heat and pressure.

• A volcano erupted, and the lava cooled very slowly to form marble.

• Wind and water eroded a mountain, and the sediment was compacted into marble.

• An ancient ocean evaporated, leaving behind layers of salt that became marble.

Multiple Choice

Imagine the Earth's internal heat suddenly disappeared, but the sun's energy remained. Which part of the rock cycle would be most directly affected and likely cease?

• The formation of igneous and metamorphic rocks.

• The formation of sedimentary rocks.

• The process of weathering and erosion.

• The entire rock cycle would speed up.

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Summary

• The rock cycle shows how the three main rock types are formed.

• The sun’s energy drives surface processes like weathering and erosion.

• Heat from Earth’s interior powers melting and metamorphism.

• Plate tectonics is the major process that drives the rock cycle.

Poll

On a scale of 1-4, how confident are you about explaining the different pathways of the rock cycle?

• 1

• 2

• 3

• 4