Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Geography AS > Earth and the crust > Flashcards

Earth and the crust Flashcards

You may prefer our related Brainscape-certified flashcards:
U.S. Geography flashcards World Geography flashcards
1
Q

define lithosphere

A

the solid layer of crust in which plates are formed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

define asthenosphere

A

soft, plastic like rock in the upper mantle, just below the lithosphere

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what is the thickness of continental crust?

A

25-70km

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what is the thickness of oceanic crust?

A

7-10km

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what age is continental crust?

A

2 billion years +

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what age is oceanic crust?

A

180-200 million years

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what is the density of continental crust?

A

2.7g cm3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what is the density of oceanic crust?

A

2.9g cm3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what rock type is continental crust?

A

granite

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what rock type is oceanic crust?

A

basalt

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what is the mineral content of continental crust?

A

aluminium, silicon, oxygen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what is the mineral content of oceanic crust?

A

silicon, magnesium and oxygen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what is the theory of ‘Paleomagnetism’?

A
  • new material is constantly being produced
  • earths magnetism flips back and forth everynow and again which results in a striped rock pattern
  • all possible due to ocean floor spreading (mid ocean ridge)
  • it is symmetrical on both sides of the ridge
  • process called ridge push
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what is the process in subduction zones called?

A
  • gravity pulls the oceanic plate down in the mantle
  • this destroys crust material and keeps the Earth in shape
  • this process is called slab pull
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

for a stable earth, what must be equal to what?

A

ridge push = slab pull

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what is earth thought to have arisen from?

A

‘planetesimals’ out of ash cloud, stuck together which produces heat from decay of uranium in core

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what is the process of movement in the mantle?

A
  • radioactive decay in the core heats material
  • heated rock rises as it is less dense
  • at the top semi molten rock spreads out, moving plates above with it
  • cools and sinks back down to be reheated
  • process repeats
18
Q

what is jigsaw fit?

A

similarities in coastlines (east coast of S. American and west coast of Africa) seem to fit like a jigsaw, suggesting they were once connected.
any gaps in the fit are likely due to erosion

19
Q

what is tectonic evidence?

A

fragments of old fold mountain belts (400-450 million years old) found spread
pieces of Calodien belt found Greenland, Canada, England, Ireland, Scotland and Scandinavia

20
Q

what is geological fit?

A

geology of S. America and W. Africa reveal ancient rock outcrop over 200 mill years both consistent on both continents

21
Q

how was the east African ridge produced?

A

(1) elevated heat flow creates bulges in Kenya and Ethiopia
(2) the brittle crust cracks into faults
(3) convection currents in asthenosphere causes the extension of crust
(3) rift continues to extend, crust becomes thinner and erupts
(4) eventually African plate splits in 2 : Nubian and Somalian

22
Q

what is the benioff zone?

A
  • the further the rock descends, the hotter the surroundings get
  • this, along with frictions heat, melts the plate into magma
23
Q

what are the types of destructive boundaries?

A

oceanic - continental
oceanic - oceanic
continental - continental

24
Q

how do fold mountains?

A
  • oceanic plate is subducted as it is more dense

- material is scraped off the subducting plates and folds up into fold mountains

25
Q

how do mid ocean ridges form?

A

(1) convection currents in the mantle move plates
(2) balsatic lava rises up
(3) lava turns into rock
(4) layers build up to form ridges

26
Q

what is the process at a constructive plate?

A
  • 2 plates move apart
  • magma rises up
  • volcanoes form
  • rift valleys form
27
Q

what is the process at a destrucive plate?

A
  • oceanic plate goes below less dense continental plate
  • plate sinks and melts
  • magma rises through cracks
  • volcanoes form
28
Q

what is the process at a collisional plate?

A
  • 2 plates of similar density move together
  • material buckles up
  • fold mountains form
29
Q

what is the process at a conservative plate?

A
  • 2 plates slide past each other

- where friction builds and slips, major earthquakes occur

30
Q

what is are the three types of hazard?

A

geophysical (driven by earths own internal energy: volcanoes, seismic activity)
atmospheric (driven by processes in the atmosphere: tropical storms)
hydrological (driven by water bodies: floods, tsunamis)

31
Q

what are the issues with perceptions of hazards?

A
  • if people are used to the threat of natural hazards, then they perceive the hazard as less of a threat
  • if people are richer, then they can flee from a hazard, and so the hazard is not as bad to them
32
Q

what is ‘fatalism’?

A

doing nothing can be seen as fatalist, as there is a

33
Q

what is the hazard management cycle?

A

preparedness
response
recovery
mitigation

34
Q

define prepardness

A

large scale events can rarely be prevented

35
Q

define reponse

A

speed of response depends on the effectiveness of plan

36
Q

define recovery

A

restoring the affected area to something like normality

37
Q

define mitigation

A

actions aimed at reducing the severity of an event

38
Q

what are the 4 steps on the park model?

A

pre-disaster
relief
rehabilitation
reconstruction

39
Q

what is the aim of the park model?

A

to improve quality of life, better than it was before

40
Q

define relief as on the park model

A

immediate local and possibly global response in form of aid, expertise and search/rescue

41
Q

define rehabilitation as on the park model

A

a longer phase lasting weeks/months when infrastructure & services are restored

42
Q

define reconstruction as on the park model

A

restoring to the same, or better, quality of life as before the event.
likely to mitigate against a similar level of disruption

Geography AS (2 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions