Ch 8: Earth Science

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 landmasses that existed at this time were joined together to form this super-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

Boundaries

Answer 10

the edges of tectonic plates

Question 11

Subduction

Answer 11

process in which two tectonic plates push against each other, and oceanic crust sinks below the less dense continental crust

Question 12

Destructive plate boundaries

Answer 12

A convergent boundary where two plates collide

Question 13

Constructive plate boundaries

Answer 13

plate that creates new land from cooling magma

Question 14

Ocean ridges

Answer 14

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 15

Conservative plate boundaries

Answer 15

boundaries between sliding plates, like the San Andreas Fault in the United States

Question 16

Laurasia

Answer 16

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

Question 17

Gondwanaland

Answer 17

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

Question 18

Hotspots

Answer 18

a localised place where an activity occurs

Question 19

Folding

Answer 19

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

Question 20

Anticlines

Answer 20

folds that bend upwards

Question 21

Synclines

Answer 21

folds that bend downwards

Question 22

Fault

Answer 22

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

Question 23

Rift valleys

Answer 23

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

Question 24

Horst

Answer 24

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

Question 25

Slip fault

Answer 25

a geological feature where movement along a fault is sideways — that is, where the blocks of crust slip horizontally past each other

Question 26

Tremors

Answer 26

vibration on the Earth's surface caused by an earthquake

Question 27

Epicentre

Answer 27

the point on the Earth's centre directly above the site where an earthquake originates

Question 28

Focus

Answer 28

the point at which an earthquake begins

Question 29

Triangulation

Answer 29

finding a location by using at least three different sources of detection

Question 30

Seismograph

Answer 30

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

Question 31

Richter scale

Answer 31

a scale that measures the amount of energy released during an earthquake

Question 32

P waves

Answer 32

compression waves that move through the Earth in the same way that sound waves move through air

Question 33

S waves

Answer 33

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 34

Body waves

Answer 34

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

Question 35

L waves

Answer 35

earthquake waves which travel only through the Earth's crust; they are responsible for the majority of an earthquake's destructive power

Question 36

Seismologists

Answer 36

a scientist who studies earthquakes

Question 37

Tsunamis

Answer 37

a powerful ocean wave triggered by an undersea earth movement

Question 38

Meltdowns

Answer 38

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

Question 39

Volcanoes

Answer 39

natural opening in the Earth's crust connected to areas of molten rock deep inside the crust

Question 40

Magma

Answer 40

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

Question 41

Lava

Answer 41

mixture of molten rock and gases that has reached the Earth's surface from a volcano

Question 42

Volcanic bombs

Answer 42

large rock fragment that is blown out of erupting volcanoes; also known as a lava bomb

Question 43

Active

Answer 43

describes a volcano that is erupting or has recently erupted

Question 44

Extinct

Answer 44

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

Question 45

Dormant

Answer 45

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