Ch 8: Earth Science Flashcards Preview

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Flashcards in Ch 8: Earth Science Deck (45):
1

Seismic Waves

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

2

Continental drift

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

3

Pangaea

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.

4

Panthalassa

the vast sea surrounding the supercontinent of Pangaea

5

Plate tectonics

the theory concerning the movement of the continental plates

6

Mantle

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

7

Convection current

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

8

Continental crust

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

9

Oceanic crust

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.

10

Boundaries

the edges of tectonic plates

11

Subduction

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

12

Destructive plate boundaries

A convergent boundary where two plates collide

13

Constructive plate boundaries

plate that creates new land from cooling magma

14

Ocean ridges

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

15

Conservative plate boundaries

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

16

Laurasia

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

17

Gondwanaland

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

18

Hotspots

a localised place where an activity occurs

19

Folding

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

20

Anticlines

folds that bend upwards

21

Synclines

folds that bend downwards

22

Fault

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

23

Rift valleys

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

24

Horst

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

25

Slip fault

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

26

Tremors

vibration on the Earth's surface caused by an earthquake

27

Epicentre

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

28

Focus

the point at which an earthquake begins

29

Triangulation

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

30

Seismograph

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

31

Richter scale

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

32

P waves

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

33

S waves

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.

34

Body waves

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

35

L waves

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

36

Seismologists

a scientist who studies earthquakes

37

Tsunamis

a powerful ocean wave triggered by an undersea earth movement

38

Meltdowns

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

39

Volcanoes

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

40

Magma

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

41

Lava

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

42

Volcanic bombs

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

43

Active

describes a volcano that is erupting or has recently erupted

44

Extinct

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

45

Dormant

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