IGCSE Theme 2 The Natural Environment Definitions

Question 1

Define the term volcano

Answer 1

A weakness in the Earth’s curst through which molten magma erupts

Question 2

Define the term strato-volcano

Answer 2

A volcano built up of alternate layers of lava and ash

Question 3

Define the term shield volcano

Answer 3

A broad volcano with gently sloping sides

Question 4

Define the term magma

Answer 4

Molten rock located under the Earth’s surface

Question 5

Define the term lava

Answer 5

Molten rock erupted from a volcano or fissure onto the Earth’s surface

Question 6

Define the term epicentre

Answer 6

The point at the surface of the Earth where the earthquake occurs

Question 7

Define the term focus

Answer 7

The source of seismic waves – the distance underground where the earthquake occurs

Question 8

Define the term fault

Answer 8

A fracture of rocks that make up the Earth’s crust

Question 9

Define the term seismic waves

Answer 9

Waves that transmit the energy released by an earthquake

Question 10

Define the term earthquake

Answer 10

The shaking of the ground caused by sudden movement in the Earth’s crust

Question 11

Define the term magnitude

Answer 11

The size or extent of an earthquake

Question 12

Define the term subduction

Answer 12

The downwards movement of the edge of a plate of the earth’s crust into the mantle

Question 13

Define the term plate

Answer 13

Large sections/part of the earth’s crust floating on the mantle

Question 14

Define the term constructive plate boundary

Answer 14

When plates are moving apart from one another

Question 15

Define the term destructive plate boundary

Answer 15

When plates move towards each other

Question 16

Define the term conservative plate boundary

Answer 16

Where the plates slide past each other

Question 17

Define the term plate boundary

Answer 17

The margin between two plates

Question 18

Define the term lahar

Answer 18

A violent mudflow composed of pyroclastic material and water

Question 19

Define the term pyroclastic flow

Answer 19

A dense, fast-moving flow of solidified lava pieces, volcanic ash, and hot gases

Question 20

Define the term drainage basin

Answer 20

An area of land drained by a river

Question 21

Define the term watershed

Answer 21

Area of high land which separates drainage basins from each other

Question 22

Define the term tributary

Answer 22

A river or stream flowing into a larger river or lake.

Question 23

Define the term confluence

Answer 23

The junction of two rivers

Question 24

Define the term interception

Answer 24

When precipitation lands on buildings, vegetation and concrete before it reaches the soil

Question 25

Define the term infiltration

Answer 25

The downward movement of water from the surface into the soil

Question 26

Define the term throughflow

Answer 26

Water flowing through the soil

Question 27

Define the term groundwater flow

Answer 27

Water flowing through the rock

Question 28

Define the term evaporation

Answer 28

The process that changes liquid water to gaseous water (water vapour)

Question 29

Define the term overland flow/surface runoff

Answer 29

Water flowing over the ground surface toward a channel

Question 30

Define the term hydraulic action (river)

Answer 30

The force of the river against the banks can cause air to be trapped in cracks and crevices. The pressure weakens the banks and gradually wears it away

Question 31

Define the term abrasion/corrasion (river)

Answer 31

The force of the water in the river carrying stones and other materials grinds the bedload like a piece of sandpaper

Question 32

Define the term attrition (river)

Answer 32

Rocks being carried by the river smash together and break into smaller, smoother and rounder particles

Question 33

Define the term solution/corrosion (river)

Answer 33

Soluble particles are dissolved by weak acids in the water

Question 34

Define the term transportation

Answer 34

When material is picked up and carried by water

Question 35

Define the term traction

Answer 35

Large boulders and rocks are rolled along the river bed

Question 36

Define the term saltation

Answer 36

Small pebbles and stones are bounced along the river bed

Question 37

Define the term suspension

Answer 37

Fine light material is carried along in the flow of the water

Question 38

Define the term solution

Answer 38

Minerals are dissolved in the water and carried along in solution (in the water)

Question 39

Define the term deposition

Answer 39

When the sea or river loses energy and drops the material it has been carrying

Question 40

Define the term flood

Answer 40

When the amount of water in a river exceeds the capacity of the channel, causing it to burst its banks onto the floodplain

Question 41

Define the term hydraulic action (coastal)

Answer 41

This is the sheer power of the waves as they smash against the cliff. Air becomes trapped in the cracks in the rock and causes the rock to break apart.

Question 42

Define the term abrasion (coastal)

Answer 42

Pebbles and rocks carried by the waves are thrown against the cliffs and act like sandpaper

Question 43

Define the term attrition (coastal)

Answer 43

Waves smash rocks and pebbles on the shore into each other, and they break and become smoother

Question 44

Define the term solution/corrosion (coastal)

Answer 44

Acids in the water wear away the rocks

Question 45

Define the term weather

Answer 45

The day-to-day condition of the atmosphere

Question 46

Define the term climate

Answer 46

The long-term pattern of weather in a particular area, typically average over a 30 year period

Question 47

Define the term ecosystem

Answer 47

A natural system that comprises a community of plants and animals that interact with each other and their physical environment

Question 48

Define the term wetted perimeter

Answer 48

Portion of the perimeter of a stream-channel cross section that is in contact with the water