GeographyICSE Class 9 · Rocks

Igneous, Sedimentary and Metamorphic Rocks and the Rock Cycle (ICSE Class 9 Geography)

Updated 17 October 2026 · Draft, not yet fact-checked

Rocks are aggregates of minerals. Igneous rocks form by cooling of magma or lava (granite, basalt); sedimentary rocks form from compressed and cemented sediments, often in layers with fossils (sandstone, limestone, shale); metamorphic rocks are changed by heat and pressure (marble, slate, quartzite, gneiss). The rock cycle links all three.

Follow the arrows: any rock can be changed into another, and deep melting returns rock to magma, so the cycle never stops.

Illustration drawn for QuestionBuddy.

Understand Igneous, Sedimentary and Metamorphic Rocks and the Rock Cycle

1. Minerals and rocks. A mineral is a natural inorganic substance with a definite chemical composition (quartz, feldspar, mica, calcite). A rock is a solid aggregate of one or more minerals (granite = quartz + feldspar + mica).

2. Igneous rocks (primary rocks). Form when molten material cools.

*Intrusive* (plutonic): cool slowly beneath the surface, large crystals, e.g. granite.
*Extrusive* (volcanic): cool quickly on the surface, small crystals or glassy, e.g. basalt.

They have no layers or fossils and are generally hard.

3. Sedimentary rocks. Weathered fragments (sediments) are transported by rivers, wind, ice or waves, deposited in layers (strata), compressed and cemented (lithification). Types: *mechanical* (sandstone, conglomerate, shale), *organic* (coal, limestone from shells), *chemical* (rock salt, gypsum). They contain layers and fossils, and are generally softer.

4. Metamorphic rocks. Existing rocks changed by heat, pressure or both without melting. Examples: limestone to marble, sandstone to quartzite, shale to slate, granite to gneiss, coal to graphite.

5. Comparison. Igneous: crystalline, no layers or fossils; sedimentary: layered, fossils; metamorphic: often banded (foliated), recrystallised, fossils rare.

6. Rock cycle. Igneous rocks weather to sediments that become sedimentary rocks; heat and pressure convert either into metamorphic rocks; deep burial melts any rock into magma that cools to igneous rock again. The cycle is continuous.

Igneous, Sedimentary and Metamorphic Rocks and the Rock Cycle: key facts

Igneous: Granite: intrusive
Basalt: extrusive
Cooling of molten material
Sedimentary: Sandstone
Limestone
Shale
Coal
Layers and fossils
Metamorphic: Limestone to marble
Shale to slate
Sandstone to quartzite
Granite to gneiss
Cycle: $M a g ma ∣ I g n eo u s ∣ S e d im e n t ∣ S e d im e n t a r y ∣ M e t am or p hi c ∣ M a g ma$

Igneous, Sedimentary and Metamorphic Rocks and the Rock Cycle in real life

The idea, met in an everyday situation. Answer the question in your own words, then compare with the model answer. The one-line hook is what to remember.

Chocolate in a pan

Suppose a student melts chocolate, lets it set and then squeezes the pieces under a heavy book.

Compare the steps with the rock cycle.

Try it first, then show the solutionSolution

Melting and setting is like magma cooling to igneous rock.
Heat and pressure change rock into metamorphic rock.

Answer: Cooling forms igneous; heat and pressure form metamorphic.

Memory hook: Melt, set, press.

Tricks to remember Igneous, Sedimentary and Metamorphic Rocks and the Rock Cycle

Short memory aids. Say each one aloud once, then use it on a question the same day.

IGNEOUS = fire
Ignis means fire.
Use it when: Origin.
SMS
Shale-slate, Marble-limestone, Sandstone-quartzite.
Use it when: Metamorphic pairs.

Igneous, Sedimentary and Metamorphic Rocks and the Rock Cycle: solved examples

Ordered from board level to HOTS. Try each one before you open the solution.

Example 1: Examples · 3 marks · Short answerBoard level

Identify the rock into which heat and pressure change (a) a calcium-rich sea-shell rock, (b) a soft clay-and-mud rock, (c) granite, giving the name of the banded metamorphic rock formed. [3]

Try it first, then show the solutionSolution

(a) Marble.
(b) Slate.
(c) Gneiss.

Answer: (a) Marble (b) Slate (c) Gneiss.

Example 2: Intrusive vs extrusive · 3 marks · Short answerHarder board level

Explain why granite has large crystals and basalt has small ones. [3]

Try it first, then show the solutionSolution

Granite cools slowly deep in the crust, so crystals grow large.
Basalt cools quickly on the surface.
Fast cooling gives small crystals.

Answer: Slow cooling gives large crystals; fast cooling gives small ones.

Example 3: Fossil clue · 4 marks · Short answerHarder board level

A rock shows layers and shell fossils. (i) Name its class. [1] (ii) Explain. [2] (iii) Name one example. [1]

Try it first, then show the solutionSolution

(i) Sedimentary.
(ii) Sediments settle in layers and bury organisms.
(iii) Limestone.

Answer: (i) Sedimentary (ii) Sediment layers trap remains (iii) Limestone.

Example 4: Rock cycle path · 4 marks · Long answerHarder board level

Trace a path in the rock cycle that starts with granite and ends with the same rock. [4]

Try it first, then show the solutionSolution

Granite weathers into sediments.
Sediments are compressed to sandstone.
Heat and pressure make quartzite.
Deep melting forms magma, which cools to granite again.

Answer: Granite, sediment, sandstone, quartzite, magma, granite.

Example 5: Case: a mason's choice · 6 marks · Case-basedHOTS / competency

Case. A sculptor chooses marble for a statue and granite for steps. (i) Parent rock of marble. [1] (ii) Class of marble. [1] (iii) Why is granite suited to steps? [2] (iv) Why can marble be carved? [2]

Try it first, then show the solutionSolution

(i) Limestone.
(ii) Metamorphic.
(iii) Granite is hard and durable.
(iv) Marble is fine-grained and softer than granite.

Answer: (i) Limestone (ii) Metamorphic (iii) Hard and durable (iv) Fine grained, workable.

Where students lose marks in Igneous, Sedimentary and Metamorphic Rocks and the Rock Cycle

The slips examiners see most often, and what to write instead.

Mistake: Saying metamorphic rocks melt
They change without melting.
Do this: Say changed by heat and pressure without melting.
Usually costs: 1 mark.
Mistake: Calling coal an igneous rock
Class confusion.
Do this: Coal is sedimentary (organic).
Usually costs: 1 mark.
Mistake: Rock cycle with only two stages
Incomplete.
Do this: Include sediment, burial and melting.
Usually costs: 2 marks.

Exam tips

Make a table of formation, features and examples.
Learn parent-product pairs.
Draw the rock cycle with labelled arrows.
State cooling rate for crystal size.

Practice questions on Igneous, Sedimentary and Metamorphic Rocks and the Rock Cycle

Write each answer on paper first. Open the hint only if you are stuck, and the answer only when you have finished.

Q1 · 1 mark · MCQBoard level
Which is an extrusive igneous rock?
(a) Granite
(b) Basalt
(c) Marble
(d) Sandstone
Hint
Surface.
Answer
(b) Basalt.
Q2 · 2 marks · Very short answerBoard level
Why are igneous rocks called primary rocks? [2]
Hint
First.
Answer
All other rocks ultimately come from them.
Q3 · 2 marks · Very short answerBoard level
Name one chemical and one organic sedimentary rock. [2]
Hint
Salt/coal.
Answer
Rock salt (chemical) and coal or limestone (organic).
Q4 · 1 mark · Assertion-reasonHarder board level
Assertion (A): Fossils are found in sedimentary rocks.
Reason (R): Igneous rocks form from very hot molten material.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
Hint
Link.
Answer
(b).
Q5 · 4 marks · Long answerHarder board level
A sample is crystalline, hard, has no layers and contains no fossils; another is layered and has shell fossils. Name each class and give two further differences. [4]
Hint
Table.
Answer
The first is igneous, the second sedimentary. Further differences: igneous forms from cooled molten rock and is generally harder; sedimentary forms from cemented sediments and is generally softer.
Q6 · 2 marks · Very short answerBoard level
Why is it difficult to find fossils in metamorphic rocks? [2]
Hint
Heat.
Answer
Heat and pressure destroy or distort the remains.
Q7 · 3 marks · Short answerHarder board level
Explain how a sedimentary rock becomes a metamorphic rock. [3]
Hint
Pressure.
Answer
It is buried deep or near magma, where heat and pressure change it without melting, for example sandstone to quartzite.
Q8 · 3 marks · Short answerHarder board level
Give two uses of each type of rock. [3]
Hint
Uses.
Answer
Granite for building; basalt for roads; sandstone and limestone for building and cement; marble for sculpture; slate for roofing.
Q9 · 4 marks · Case-basedHOTS / competency
Case. A cliff shows alternating bands of hard and soft rock in layers, with a vertical dark band cutting across them. (i) Class of the layered rock. [1] (ii) Class of the dark band. [1] (iii) What is the band called and how was it formed? [2]
Hint
Dyke.
Answer
(i) Sedimentary. (ii) Igneous. (iii) A dyke, formed when magma filled a crack and cooled.
Q10 · 3 marks · Long answerHOTS / competency
Case. A student claims rock cycle always follows one fixed order. Evaluate with an example. [3]
Hint
Shortcuts.
Answer
Not so; rocks can take shortcuts, such as igneous to metamorphic directly, or sedimentary to sedimentary after weathering.

Test your recall

Answer in your head or on paper first, then open the card. Pulling an answer out of memory makes it stick far better than re-reading.

1.Granite is?Show answer
Intrusive igneous.
2.Slate comes from?Show answer
Shale.
3.Layers are found in?Show answer
Sedimentary rocks.
4.Marble comes from?Show answer
Limestone.
5.Primary rocks?Show answer
Igneous rocks.

Igneous, Sedimentary and Metamorphic Rocks and the Rock Cycle: frequently asked questions

What is lithification?

Turning sediment into rock.

Is coal a mineral?

It is a rock of organic origin.

Is a rock a mineral?

No, a rock is made of minerals.