C2.5: The rock cycle

Lesson focus: Can one rock type become another?

Learning objective

Trace more than one pathway through the .

Build on earlier learning

Sedimentary rocks

Combine sedimentary processes into a larger Earth system.

You will be successful when you can…

Name three rock groups and sediment/magma.
Label process arrows.
Trace two valid pathways.
Explain why no fixed sequence exists.

KEY VOCABULARY

Words that carry the science

rock cycle: Network of processes that transform Earth materials.
lithification: Compaction and cementation that turn sediment into rock.
uplift: Movement that brings buried rock toward the surface.
melting: Change from solid rock to molten material.
solidification: Cooling of molten material to form solid rock.

BUILD YOUR UNDERSTANDING

Navigate a network of rock changes rather than memorising a circle

01Every arrow needs a process

Rock-group names are stores or states in the network. Weathering, erosion, , metamorphism, , cooling and make the changes.

02Many routes are possible

Any exposed rock can weather. Suitable buried rocks can metamorphose. Any rock that melts enters magma before later .

03Timescales vary enormously

Some eruptions cool quickly; burial, uplift and mountain building can take millions of years. A diagram is not a timetable.

Figure · The rock cycle is a network with no compulsory starting point or fixed timescale. Any exposed rock can weather; any suitable rock can metamorphose; melting creates magma, not metamorphic rock.

Animation

The rock cycle

Rocks are slowly changed from one type into another over millions of years. Step through each process.

Step 1 of 7

Deposition, compaction and cementationLayers of sediment settle, are squashed by the layers above and are cemented together.

WORKED EXAMPLE

Trace granite to quartzite and onward

Connect granite → sediment → sandstone → quartzite → magma → igneous rock.

Weathering and erosion turn exposed granite into sediment.
Deposition, compaction and cementation form sandstone.
Heat and pressure without melting form quartzite.
Melting makes magma; cooling and solidification form igneous rock.

How to make the reasoning visible: Every transition is justified by a named process, including magma between melting and igneous rock.

LEARN BY DOING

Route builder

Complete each transition using only processes that can produce the stated result.

Start	Process(es)	End	Check
Igneous	Weathering → erosion	Sediment	Exposure needed
Sediment	Deposition → lithification	Sedimentary	No melting
Sedimentary	Heat + pressure	Metamorphic	Remains solid
Metamorphic	Melting	Magma	Not igneous yet
Magma	Cooling + solidification	Igneous	Crystal size varies

Can metamorphic rock become sedimentary rock without first becoming magma?
Your answer
Why place magma between melting and igneous rock?
Your answer
Use the route builder. Describe a route from igneous rock to sedimentary rock.
Your answer

RETRIEVE · APPLY · CHECK

Check your understanding

Answer from memory, then check against the suggested answer.

What is rock cycle?

What is lithification?

What is uplift?

What process turns magma into igneous rock?

What is needed to turn sedimentary rock into metamorphic rock?

Apply the idea

Describe one route from igneous to sedimentary rock.

Stretch and challenge

Why is a circular diagram potentially misleading?

Why is it called a rock cycle?

Exam Question Practice

C2.5Describe5 marks

Exam Question Practice

Mark points shown after marking

Describe a pathway by which an igneous rock can become a sedimentary rock.

(5)

Total for this question: 5 marks

Command word: Award yourself credit only for process names linked in a viable order.