The Rock Cycle

The Rock Cycle

Middle School

​

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

​

Rock Cycle

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

​

Weathering

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

​

Igneous Rock

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

​

Sedimentary Rock

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

​

Metamorphic Rock

A rock changed by extreme heat, pressure, or chemical reactions deep within the Earth.

​

Plate Tectonics

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

​

​

What Is the Rock Cycle?

• The rock cycle is a model for how matter cycles on Earth.

• It shows how rocks change from one type to another.

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

• These rock changes happen very slowly over millions of years.

Multiple Choice

What does the rock cycle model illustrate?

• How the Earth's interior produces heat and light.

• How energy from the sun is captured and stored in rocks.

• How matter cycles and transforms into different rock types on Earth.

• How geologic time is measured in millions of years.

​

​

From Magma to Rock: The Creation of Igneous Rocks

• Intense heat inside Earth melts solid rock, forming a liquid called magma.

• When this magma starts to cool, its atoms form an orderly structure.

• This process, called crystallization, creates new solid igneous rocks.

• The speed of cooling determines the size of the crystals in the rock.

Multiple Choice

What is the relationship between melting and crystallization in the rock cycle?

• Both processes create liquid magma.

• Both processes are caused by the rapid cooling of rock.

• Melting creates hot magma, and crystallization turns that magma back into a solid rock.

• Melting cools magma, and crystallization heats up solid rock.

​

​

Internal Energy: Deformation & Metamorphism

Deformation

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

• ​​This process changes the original shape and structure of the rock layers.

• ​It often occurs where tectonic plates collide, leading to mountain formation.

Metamorphism

• ​Intense heat and pressure change the minerals within a rock without melting it.

• ​​This physical and chemical transformation creates a new type of metamorphic rock.

• ​For example, sedimentary limestone can be transformed into the metamorphic rock marble.

Multiple Choice

What is the primary difference between rock deformation and metamorphism?

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

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

• Deformation changes a rock's shape, while metamorphism changes its mineral composition without melting.

• Deformation creates new rock, while metamorphism destroys it.

​

​

Solar Energy's Role in Reshaping Earth

• The sun’s energy drives weather, which causes the breakdown of rocks (weathering).

• Weathering breaks down large rocks into smaller pieces called sediment.

• Erosion is the movement of this sediment by agents like wind and water.

• Sedimentation is when sediment settles, eventually forming new sedimentary rock.

​

Multiple Choice

What is the relationship between weathering and erosion?

• They are different words for the exact same process.

• Weathering breaks down rocks, and erosion moves the resulting sediment.

• Erosion breaks down rocks, and weathering moves the resulting sediment.

• Erosion forms new rock, and weathering causes it to settle.

​

​

Plate Tectonics: The Rock Cycle's Driving Force

• Plate tectonics is the theory that connects all rock cycle processes.

• ​Earth's internal heat creates convection currents that move the tectonic plates.

• Colliding plates create pressure, leading to deformation and metamorphic rock formation.

• A subducting plate melts into magma, which cools into new igneous rock.

​

Multiple Choice

What is the primary energy source that drives the movement of Earth's tectonic plates?

• The force of strong ocean currents

• The energy from the Sun warming the surface

• The internal heat from Earth's core and mantle

• The gravitational pull of the Moon

​

Common Misconceptions

Misconception	Correction
Rocks are permanent and do not change.	The rock cycle is a continuous, very slow process that changes rocks.
The rock cycle follows a single, circular path.	It's a complex web where any rock can become any other rock type.
Rock formation happens quickly.	Rock formation and mountain building are very slow, taking millions of years.
Surface and interior processes are separate.	They are interconnected; internal energy drives processes that push rocks to the surface.

Multiple Choice

How do the two main energy sources, the sun and Earth's interior, contribute differently to the rock cycle?

• Both sources primarily cause rocks to melt into magma.

• The sun's energy drives surface processes like weathering, while Earth's internal heat drives processes like metamorphism.

• Earth's internal heat is responsible for erosion, while the sun's energy causes magma to crystallize.

• The sun heats the Earth's core, which in turn melts rock.

Multiple Choice

A rock found deep within a mountain range shows signs of being squeezed and heated, with its minerals recrystallized but not melted. How would you classify this rock and why?

• Igneous, because it was heated.

• Sedimentary, because it's found in a mountain.

• Metamorphic, because it was changed by heat and pressure without melting.

• Magma, because it has been recrystallized.

Multiple Choice

Imagine a scenario where tectonic plate movement completely stops, but the sun's energy remains. Which parts of the rock cycle would be most significantly affected?

• Weathering and erosion would stop completely.

• The formation of metamorphic and igneous rocks would be greatly reduced, while sedimentary rock formation might continue.

• Only the formation of igneous rock would be affected.

• The rock cycle would speed up due to the lack of plate movement.

Multiple Choice

A geologist discovers an igneous rock layer composed of very large, well-formed crystals. What can be inferred about the formation environment of this rock?

• The rock formed from rapidly cooled lava on the surface.

• The rock formed from slowly cooled magma deep beneath the surface.

• The rock was subjected to intense pressure, which enlarged its crystals.

• The rock is actually sedimentary, as large crystals only form from settled sediment.

​

Summary

• The rock cycle explains how igneous, sedimentary, and metamorphic rocks form.

• The sun's energy powers surface processes like weathering and erosion.

• Heat from Earth's interior drives melting and metamorphism.

• Plate tectonics is a key driver of the rock cycle.

• Rock cycle changes happen over millions of years.

• Any rock can change into any other type of rock.

Poll

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

• 1

• 2

• 3

• 4