The Dynamic Earth

Question 1

plate tectonics

Answer 1

the theory concerning the movement of the continental plates

Question 2

mantle

Answer 2

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 3

convection current

Answer 3

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

Question 4

continental crust

Answer 4

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

Question 5

oceanic crust

Answer 5

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 6

boundaries

Answer 6

the edges of tectonic plates

Question 7

subduction

Answer 7

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

Question 8

destructive plate boundaries

Answer 8

a convergent boundary where two plates collide

Question 9

constructive plate boundaries

Answer 9

plate that creates new land from cooling magma

Question 10

ocean ridges

Answer 10

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 11

conservative plate boundaries

Answer 11

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

Question 12

laurasia

Answer 12

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

Question 13

Gondwanaland

Answer 13

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

Question 14

hotspots

Answer 14

a localised place where an activity occurs

Question 15

seismic waves

Answer 15

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

Question 16

continental drift

Answer 16

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

Question 17

Pangaea

Answer 17

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 18

panthalassa

Answer 18

the vast sea surrounding the supercontinent of Pangaea

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/ Primary Waves

Answer 32

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

Question 33

Secondary 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

surface waves

Answer 35

(or L-waves) 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