Earth’s resources

What is a rock?

A naturally occurring solid made of minerals.

What is a mineral?

A naturally occurring substance with a specific chemical composition.

Why are minerals important in rocks?

Minerals determine the properties and appearance of rocks.

What is the difference between rocks and minerals?

Rocks are mixtures of minerals, while minerals are pure substances.

What are the three main rock types?

Igneous, sedimentary and metamorphic.

How are igneous rocks formed?

By the cooling and solidification of magma or lava.

What is magma?

Molten rock beneath Earth’s surface.

What is lava?

Molten rock on Earth’s surface.

Why do igneous rocks have crystals?

Minerals crystallise as magma cools.

How does cooling rate affect crystal size in igneous rocks?

Slow cooling forms large crystals; fast cooling forms small crystals.

What is granite?

A coarse-grained intrusive igneous rock.

What is basalt?

A fine-grained extrusive igneous rock.

What are sedimentary rocks formed from?

Layers of sediment compacted and cemented together.

What are sediments?

Small particles of rock, minerals or organic material.

Why do sedimentary rocks often contain fossils?

They form in layers without extreme heat or pressure.

What is metamorphic rock?

Rock changed by heat and pressure.

How are metamorphic rocks formed?

Existing rocks are altered by high heat and pressure underground.

What is an example of a metamorphic rock?

Marble or slate.

How does metamorphism change rocks?

It alters crystal structure and physical properties.

What is the rock cycle?

The continuous process of rock formation and transformation.

Why is the rock cycle important?

It explains how rocks change between types over time.

What is weathering?

The breakdown of rocks at Earth’s surface.

What is erosion?

The movement of weathered rock particles.

What are fossils?

Remains or traces of ancient organisms preserved in rock.

Why are fossils usually found in sedimentary rocks?

Extreme heat and pressure destroy fossils in other rock types.

What is Earth’s crust?

The thin outer layer of Earth.

What is the mantle?

The thick layer beneath the crust made of semi-molten rock.

What is Earth’s outer core made of?

Liquid iron and nickel.

What is Earth’s inner core made of?

Solid iron and nickel.

Why is the inner core solid despite high temperatures?

Extreme pressure prevents melting.

What causes tectonic plates to move?

Convection currents in the mantle.

What are tectonic plates?

Large sections of Earth’s crust that move slowly.

What happens at tectonic plate boundaries?

Earthquakes, volcanoes and mountain formation may occur.

What is a destructive plate boundary?

A boundary where plates move towards each other.

What is a constructive plate boundary?

A boundary where plates move apart.

What is a conservative plate boundary?

A boundary where plates slide past each other.

Why do earthquakes occur?

Stress builds up as tectonic plates move and suddenly release energy.

Why do volcanoes often form near plate boundaries?

Magma rises through weaknesses in Earth’s crust.

What is an intrusive igneous rock?

An igneous rock formed underground from slowly cooled magma.

What is an extrusive igneous rock?

An igneous rock formed at Earth’s surface from rapidly cooled lava.

Why is granite coarse-grained?

It cooled slowly underground.

Why is basalt fine-grained?

It cooled quickly at the surface.

What properties do metamorphic rocks often have?

They are hard, dense and resistant to weathering.

Why is marble used in buildings and statues?

It is strong and can be polished.

How does heat affect rocks during metamorphism?

It causes minerals to recrystallise.

What role does pressure play in metamorphism?

It compresses minerals and changes rock texture.

Why are rocks important resources?

They provide materials for construction, fuels and industry.