MS-ESS2-1: Rock Cycle and Energy Flow

MS-ESS2-1
Rock Cycle and Energy Flow

Middle School

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Learning Objectives

• Describe the cycling of Earth's materials through weathering, sedimentation, melting, and crystallization.

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

• Define physical and chemical weathering and provide examples of each.

• Describe the conditions of heat and pressure required to form metamorphic rocks.

Key Vocabulary

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Rock Cycle

The rock cycle is a model showing how rocks continuously change from one type to another.

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Weathering

Weathering is the natural process that breaks down large rocks into much smaller pieces called sediment.

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Erosion

Erosion is the process of moving weathered rock fragments and sediment from one place to another.

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Sedimentation

Sedimentation occurs when transported sediments are deposited and settle in a new location, often in layers.

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Deformation

Deformation is the process where a rock's original shape is changed by intense heat or pressure.

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Crystallization

Crystallization is when magma or lava cools and hardens, which forms interlocking mineral crystals.

Key Vocabulary

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Solar Energy

Energy from the sun that drives the various processes that occur on the surface of the Earth.

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Geothermal Energy

Energy derived from the heat of the Earth's interior, which drives the internal processes of our planet.

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Metamorphic Rock

A type of rock that has been fundamentally changed by being exposed to extreme heat and pressure.

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Foliation

The parallel alignment of minerals within a rock, which creates a layered or banded appearance in metamorphic rocks.

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Earth's Energy Engines

Solar Energy

• Energy from the sun is the main driver for all of the processes on Earth's surface.

• It is responsible for creating our weather patterns, including the wind and the water cycle.

• These surface processes are the main causes of weathering and the erosion of our landscapes.

Geothermal Energy

• Energy from Earth's hot interior drives processes that occur deep beneath the surface.

• This powerful internal heat causes the melting, crystallization, and deformation of rock.

• Geothermal energy is also the force that is responsible for moving the tectonic plates.

Multiple Choice

What are the two primary sources of energy that power Earth's surface and subsurface processes?

• Solar energy and geothermal energy

• Wind energy and water energy

• Tectonic energy and magnetic energy

• Fossil fuels and nuclear energy

Multiple Choice

How does energy from the sun lead to the weathering and erosion of Earth's landscapes?

• It powers the weather and water cycle, which are surface processes that break down and move rock.

• It directly heats and melts the rock on Earth's surface, causing it to break apart.

• It causes the movement of tectonic plates, which creates mountains that then erode.

• It provides light for plants to grow, and their roots break apart the rocks.

Multiple Choice

A geologist observes the formation of new rock deep underground and the slow movement of a continent. Which of the following provides the best explanation for the energy source driving these events?

• Heat from Earth's interior is causing rock to melt and is moving the tectonic plates.

• Energy from the sun is heating the surface, which causes the continent to expand and move.

• Weathering and erosion on the surface are creating pressure that melts rock deep underground.

• The wind and water cycle are powerful enough to move continents and create new rock.

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The Rock Cycle: A Matter of Transformation

• The rock cycle describes how matter cycles and Earth materials are formed.

• ​This model shows how any rock can be transformed into another rock type.

• Solar energy drives surface processes like weathering and erosion of rocks.

• Geothermal energy drives melting, deformation, and crystallization deep inside the Earth.

Multiple Choice

What is the main purpose of the rock cycle model?

• To show how Earth's materials are formed and changed over time.

• To explain how solar energy creates weather patterns.

• To describe how geothermal energy heats the Earth's core.

• To map the locations of different types of rocks on Earth.

Multiple Choice

Which of the following describes a process in the rock cycle that is driven by solar energy?

• The melting of rock deep inside the Earth.

• The breakdown and movement of rock sediment on the surface.

• The crystallization of new rock from internal heat.

• The pushing of new rock from inside the Earth to the surface.

Multiple Choice

Based on the sources of energy that drive the rock cycle, what is the most likely consequence if the Earth's internal geothermal energy were to significantly decrease?

• The formation of new rocks through melting and crystallization would decrease.

• The breakdown of rocks on the surface by weathering would stop.

• The movement of sediment by erosion would completely cease.

• The energy from the sun would become the only force driving the cycle.

Weathering, Erosion, and Sedimentation

• Weathering is the breakdown of rock into smaller pieces called sediment.

• Erosion transports this sediment to a new location using water, wind, or ice.

• Sedimentation happens when transported sediment settles down in a new place.

Multiple Choice

What is the term for the breakdown of rock into smaller pieces called sediment?

• Weathering

• Erosion

• Sedimentation

• Deposition

Multiple Choice

What is the primary relationship between weathering and erosion?

• Weathering breaks down rock, and erosion carries the sediment away.

• Erosion breaks down rock, and weathering carries the sediment away.

• Weathering and erosion are two words for the same process.

• Erosion happens first, followed by the sedimentation of rock.

Multiple Choice

A fast-flowing river is carrying sediment down a steep mountain. What is the most likely outcome when the river reaches a flat valley and slows down?

• The sediment will be deposited at the bottom of the valley.

• The river will start to flow uphill.

• The sediment will be converted back into a large rock.

• The water will evaporate, leaving the sediment suspended in the air.

Physical Weathering: Breaking Rocks Apart

• Physical weathering breaks rocks into smaller pieces without any chemical changes.

• Abrasion scrapes rocks, while ice wedging cracks them apart with expanding ice.

• Plant roots can grow into cracks, forcing rocks apart over time.

Multiple Choice

What is the definition of physical weathering?

• Rocks are broken into smaller pieces without any chemical change.

• Rocks are dissolved by acid rain, changing their composition.

• Rocks are melted by intense heat to form magma.

• Rocks are formed by the cooling of lava.

Multiple Choice

What do the processes of ice wedging and plant root growth have in common?

• They both involve forces that expand within cracks to push rocks apart.

• They both scrape the surface of the rock, wearing it down.

• They both use water to dissolve the minerals that hold rocks together.

• They both rely on wind to carry away small particles of rock.

Multiple Choice

A large boulder falls into a cold, fast-flowing mountain river that frequently freezes in winter. Which weathering process would likely be most effective at breaking the boulder apart over time?

• Ice wedging, as water would repeatedly freeze and expand in the rock's cracks.

• Abrasion, as the rock would be scraped by other rocks in the river.

• Plant roots, as trees would quickly grow into the rock's cracks.

• Chemical weathering, as the river water would dissolve the rock.

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Chemical Weathering: Changing Rock Composition

• Chemical weathering breaks down rocks using chemical reactions, changing the rock's composition.

• Rainwater absorbs carbon dioxide, creating a weak carbonic acid that dissolves limestone.

• This dissolution creates landforms like caves and sinkholes, known as karst topography.

• Weak acids break down feldspar in granite into clay, releasing quartz crystals.

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Multiple Choice

What is the primary effect of chemical weathering on a rock?

• It breaks the rock into smaller pieces.

• It moves the rock to a new location.

• It changes the chemical composition of the rock.

• It fuses smaller rocks together into a larger rock.

Multiple Choice

How does rainwater create landforms like caves and sinkholes?

• By freezing and expanding in the cracks of limestone.

• By physically washing away the surface of the limestone.

• By absorbing carbon dioxide to form a weak acid that dissolves limestone.

• By breaking down feldspar into clay within the limestone.

Multiple Choice

If a piece of granite is left in a weak acid for many years, what materials would likely be left behind?

• Unchanged feldspar and granite

• Clay and quartz crystals

• Limestone and sinkholes

• Small pebbles of pure granite

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Differential Erosion: Hard vs. Soft Rock

Soft Rock

• Softer rock, like shale, wears away much more quickly when exposed to wind and water.

• At Niagara Falls, water erodes a soft shale layer under a harder limestone layer.

• This undercutting of soft rock causes the harder rock above it to eventually collapse.

Hard Rock

• Harder, more resistant rock, like limestone or volcanic rock, erodes at a much slower rate.

• When the surrounding soft rock is worn away, the hard rock is left behind.

• Devils Tower is a famous example of hard volcanic rock left after softer rock eroded.

Multiple Choice

Which statement best describes differential erosion?

• The process where all rocks turn into soil.

• The process where different types of rock wear away at different rates.

• The process where hard rock breaks down soft rock.

• The process where water freezes and expands in rock cracks.

Multiple Choice

At Niagara Falls, how does the erosion of the soft shale layer affect the hard limestone layer above it?

• The hard rock dissolves in the water, making it weaker.

• The removal of the soft rock layer below leaves the hard rock unsupported, causing it to collapse.

• The pressure from the water compacts the soft rock into hard rock.

• The hard rock absorbs water and becomes softer over time.

Multiple Choice

Based on the process that formed Devils Tower, what would be the most likely outcome if a large area of soft rock with a core of hard volcanic rock is exposed to erosion for a long time?

• A tall column of hard volcanic rock would remain as the surrounding softer rock wears away.

• The entire area would erode at the same rate, creating a flat plain.

• The hard volcanic rock would erode first, leaving a large crater.

• A deep canyon would form as the volcanic rock is carried away by water.

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How Metamorphic Rocks Form

• Metamorphic rocks form when existing rocks are changed by heat and pressure.

• Heat from deep within the Earth alters the rock without melting it.

• Immense pressure from rock layers or plate collisions squeezes the existing rock.

• This process causes deformation, creating new minerals and a new rock structure.

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Multiple Choice

What two factors are primarily responsible for changing an existing rock into a metamorphic rock?

• Heat and pressure

• Melting and cooling

• Weathering and erosion

• Compaction and cementation

Multiple Choice

According to the process of metamorphism, what is the combined effect of heat and pressure on an existing rock?

• It causes the rock to deform and create new minerals.

• It melts the rock completely into magma.

• It breaks the rock into smaller pieces called sediment.

• It perfectly preserves the original rock structure.

Multiple Choice

A layer of shale is buried deep underground by the collision of tectonic plates, but the temperature is not high enough to melt it. What is the most likely outcome for the shale?

• The rock's minerals and structure will be changed by the immense pressure and heat.

• The rock will melt into magma because of the high temperatures.

• The rock will be broken down into sand and clay by the pressure.

• The rock will remain completely unchanged despite the conditions.

Features of Metamorphic Rocks

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Hardening

• ​Mineral particles in the rock become more strongly cemented together.

• ​​For example, quartz grains in sandstone can fuse together.

• ​This creates a very hard metamorphic rock called quartzite.

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Foliation

• ​Pressure causes minerals to rearrange into parallel, wavy layers or bands.

• ​​This is a noticeable feature of deformation in metamorphic rocks.

• ​Gneiss has wide bands, while schist has finer, narrower bands.

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Re-crystallization

• ​During metamorphism, atoms of minerals rearrange into new crystal structures.

• ​​This process forms entirely new minerals within the existing rock.

• ​This incredible transformation happens without the rock actually melting.

Multiple Choice

What do the processes of hardening, foliation, and re-crystallization have in common?

• They are all types of sedimentary rocks.

• They are all changes that occur in rocks during metamorphism.

• They are all processes that involve the melting of rock.

• They are all names of specific minerals found in rocks.

Multiple Choice

What underlying process causes the changes of re-crystallization and foliation in metamorphic rocks?

• The complete melting and cooling of the original rock.

• The rearrangement of mineral atoms and particles under pressure without melting.

• The cementing of sand grains together to form sandstone.

• The breaking down of rocks into smaller pieces by weathering.

Multiple Choice

A rock containing a mixture of light and dark minerals is exposed to intense, directed pressure. Based on the principles of metamorphism, what is the most likely outcome?

• The rock will become much softer and easier to break.

• The rock will melt completely to form a new igneous rock.

• The rock will develop parallel bands of different colored minerals.

• The minerals in the rock will become randomly scattered.

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Common Misconceptions

Misconception	Correction
Weathering and erosion are the same thing.	Weathering breaks down rock, while erosion moves the broken pieces.
Metamorphic rocks are formed when rocks melt.	Metamorphic rocks get hot and deform, but do not melt.
All rocks weather at the same rate.	Softer rocks weather and erode much more quickly than harder rocks.
Landforms are permanent and don't change.	Landforms are constantly changing due to slow Earth processes.

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Summary

• The rock cycle is driven by the Sun's energy and Earth's internal heat.

• Surface processes like weathering and erosion break down and move rock.

• Internal heat and pressure can change any rock into a metamorphic rock.

• Landforms seem stable but are always changing over very long periods.

Poll

On a scale of 1-4, how confident are you about the concepts covered in today's review?

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