Chapter 8 - The Earth

Question 1

Seismic waves

Answer 1

Waves of energy that travel through the Earth’s crust, caused by earthquakes.

Question 2

Continental drift

Answer 2

Movement of the plates of the Earth’s crust in relation to each other.

Question 3

Pangaea

Answer 3

A super-continent that existed about 225 million years ago. All of the landmass that existed at this time were joined together to form this upper-continent.

Question 4

Panthalassa

Answer 4

The vast sea surrounding the supercontinent of Pangaea.

Question 5

Plate tectonics

Answer 5

The theory concerning the movement of the continental plates.

Question 6

Mantle

Answer 6

Thick layer inside the Earth, below the crust. Most of the mantle is solid rock, although the upper part is molten rock called magma.

Question 7

Convection current

Answer 7

Circular movement that occurs when warmer, less dense fluid particles rise and cooler, denser fluid particles sink.

Question 8

Continental crust

Answer 8

The plates of the Earth’s crust that make up the land

Question 9

Oceanic crust

Answer 9

One of the types of crust that makes up the Earth’s outer layer. Oceanic crust is thinner than continental crust and made up of dense, heavy rocks such as basalt.

Question 10

Subduction

Answer 10

Process in which two tech tonic plates push against each other, and oceanic crust sinks below the less dense continental crust.

Question 11

Destructive plate boundaries

Answer 11

A convergent boundary where two plates collide

Question 12

Constructive plate boundaries

Answer 12

Plate that creates new land from cooling magma

Question 13

Ocean ridges

Answer 13

An area where the tectonic plates move apart, allowing magma from the mantle to rise, forming underwater volcanoes and creating new oceanic crust as it is cooled and solidified by sea water.

Question 14

Laurasia

Answer 14

One of the two smaller continents created when the supercontinent Pangaea broke apart about 200 million years ago.

Question 15

Gondwanaland

Answer 15

One of the two smaller continents created when the supercontinent Pangaea broke apart about 200 million years ago.

Question 16

Hotspots

Answer 16

A localised place where an activity occurs

Question 17

Folding

Answer 17

Buckling of rocks caused when rocks are under pressure from both sides

Question 18

Anticline

Answer 18

Folds that bend upwards

Question 19

Syncline

Answer 19

Folds that bend downward

Question 20

Fault

Answer 20

A break in a rock structure causing a sliding movement of the rocks along the break

Question 21

Rift valleys

Answer 21

A sunken area where two blocks of crust have dropped down between faults

Question 22

Horst

Answer 22

A block of the Earth’s crust, with faults on either side, that has been pushed upwards by the forces

Question 23

Slip fault

Answer 23

A geographical feature where movement along a fault is sideways-that is where the blocks of crust slip horizontally past each other.

Question 24

Tremors

Answer 24

Vibration on the Earth’s surface caused by an earthquake.

Question 25

Epicentre

Answer 25

The point on the Earth’s centre directly above the site where an earthquake originates.

Question 26

Focus

Answer 26

The point at which an earthquake begins

Question 27

Triangulation

Answer 27

Finding a location by using at least three different sources of detection.

Question 28

Seismograph

Answer 28

An instrument used to detect and measure the intensity of an earthquake

Question 29

Richter scale

Answer 29

A scale that measures the amount of energy released during an earthquake.

Question 30

Primary waves (p-waves)

Answer 30

Compression waves that move through the Earth in the same way that sound waves move though air.

Question 31

Secondary waves (s-waves)

Answer 31

The second set of waves to be detected after P-waves. During seismic activity, secondary waves or s-waves travel in the form of transverse waves.

Question 32

Body waves

Answer 32

Waves that travel through the interior of the Earth; P-waves and S-waves are said to be body waves.

Question 33

Seismologists

Answer 33

A scientist who studies earthquakes

Question 34

Tsunamis

Answer 34

A powerful ocean wave triggered by an undersea earth movement.

Question 35

Meltdowns

Answer 35

The melting of a nuclear-reactor core as a result of a serious nuclear accident

Question 36

Volcanoes

Answer 36

Natural opening in the Earth’s crust connected to areas of molten rock deep inside the crust.

Question 37

Magma

Answer 37

A very hot mixture of molten rock and gases, just below the Earth’s surface, that has come from the mantle.

Question 38

Lava

Answer 38

Mixture of molten rock and gases when it has reached the Earth’s surface of a volcano.

Question 39

Volcanic bombs

Answer 39

Large rock fragment that is blown out of erupting volcanoes.

Question 40

Active

Answer 40

Describes a volcano that is erupting or has recently erupted.

Question 41

Extinct

Answer 41

Describes a volcano that has not erupted for thousands of years and is effectively dead.

Question 42

Dormant

Answer 42

Describes a volcano that has not erupted for more than 20 years but is not considered extinct.