PLATE TECTONICS Flashcards

1
Q

who came up with the continental drift theory

A

Alfred wegener

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2
Q

what’s the name of the one land mass?

A

panagea

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3
Q

what is the name of the 2 land masses once it split?

A

laurasia and gondawanaland

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4
Q

what evidence is there to prove plate tectonics?

A

fit of continents
fossils
climate and ice
palaeomagentism and sea floor spreading

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5
Q

what is palaeomagentism?

A

magnetic field of igneous rock containing minerals(eg. iron) which aligned at time of cooling.
EG. symmetrical pattern either side of mid atlantic ridge

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6
Q

structure of the earth

A

inner core
outer core mantle
upper mantle (aethenosphere and lithosphere)
crust

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7
Q

what is moho discontinuity?

A

change in composition between thin outer skin of crustal rock and upper mantle.

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8
Q

what are the 4 plate boundaries?

A

constructive(divergent)
destructive(convergent)
conservative(transform)
collision

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9
Q

what is a constructive/divergent plate boundary?

A

2 plates move apart
gentle volcanic activity and minor earthquakes
new islands form as crust emerges

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10
Q

what is a destructive/convergent plate boundary?

A

subduction zone
2 plates move towards each other
-trenches,earthquakes,violent volcanos
oceanic under continental

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11
Q

what is a conservative/transform plate boundary?

A

2 plates sliding past each other
earthquakes
crust not lost or made

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12
Q

what is a collision plate boundary?

A

continental plate colliding
fold mountains
violent earthquakes
crust not lost or made

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13
Q

characteristics of a oceanic plate

A

8km thick
3.2g/cm^3
iron and magnesium

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14
Q

characteristics of a continental plate

A

30-70km thick
2.7g/cm^3
silicone and aluminium

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15
Q

how to plates move?

A

convection currents

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16
Q

what is orogenesis?

A

process of mountain building

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17
Q

what is orogeny?

A

period of time mountains take to form

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18
Q

what is the basic process of orogenesis?

A

compression
folding
uplift

19
Q

what are fold mountains?

A

folding of rock in strata in the upper part of the crust

sedimentary rock

20
Q

what is a volcanic island arcs form?

A

volcanoes in a arc shape

generally due to subduction of oceanic plate

21
Q

how do oceanic trenches form?

A

long narrow depressions in sea floor
deepest part of ocean
moves from few mm to over 10cm
occurs at a subduction zone

22
Q

case study : how do the Himalayas form?

A

60 million years ago - indian and Asian plate collide
push against each other
crust squeezed upwards
40 million years ago- heavy sediment sinks under Asian plate. closing up the Tethys sea

20 million years ago- Tethys sea gone. sediment pushed up to from Himalayas. Tibet begins to rise

today - indian plate continues to rise due to squeezing

predictions for 10 million years from now
Nepal no longer exists. mountains continue to form advancing edge of india.

23
Q

what is a volcano?

A

a volcano is a vent in the earth’s crust geographical landform where magma erupts through the surface.

24
Q

what are the 3types of lava?

A

basaltic, andesitic and rhyolitic

25
Q

what are the properties of andesitic lava?

A
high silica content 
less frequent
800c
viscous
violent
ash,steam,lava,tephra
26
Q

what are properties of basaltic lava?

A
frequent
gentle
low viscosity
1200c
lava and steam
low silica content
27
Q

what are the 6 types of volcanos

A
fissure
shield
ash/cinder
caldera
strato/composite
acid/dome
28
Q

what is a fissure volcano?

A

basaltic lava
effusive eruptions
spreads wide and far

29
Q

what is a shield volcano?

A

builds up from previous eruptions
basaltic lava
slightly domed

30
Q

what is a ash or cinder volcano?

A

mainly ash and tephra
30m to 400m high
pyroclastic material

31
Q

what is a caldera?

A

circular depression
huge eruption
collapse of magma chamber

32
Q

what is a strato or composite volcano?

A

basaltic and andesitic lava
layers in rock
tall/concial mountain

33
Q

what is an acid/dome?

A

steep sided
convex cone
andesistic lava

34
Q

2 examples of igneous rock

A

granite and basalt

35
Q

properties of basalt

A

extrusive
small crystals- short time to cool
dense
constructive plate boundary

36
Q

properties of granite

A
large crystals
long time to cool
less dense
destructive plate boundaries
long time to cool 
in aesthenosphere
37
Q

what is a lava plateau?

A

intrusive and extrusive
flat/wide surface
lava spreads quickly

38
Q

what are the 2 types of plutons?

A

batholith and laccoliths

39
Q

what is a batholith?

A

under earths surface molten rock injected into crust

1 to 100 cubic km

40
Q

what is a laccolith ?

A

close to earths surface
causing rock to bend
intrusive

41
Q

what is a dyke?

A

discordant
cuts across layers of bedding
crystalised or fine grains

42
Q

what is a sill?

A

concordant
sheetlike
injection into current bedding rock
1 to 100 metres thick

43
Q

what is an extinct volcano ?

A

extrusive
no lava supply
no longer near an active hotspot

44
Q
case study : mount etna 
location
plate boundary
type of volcano
impacts
A

location: east coast sicily Italy. 100km south of messina and 30km north of Catania

plate boundary: subduction of African under Eurasian. destructive plate boundary

type of volcano: stratovolcano on top of shield volcano
3323m high, explosive eruptions. acid lava

2002-2003 impacts social:
1000 leave their homes
100 homes damages
schools shut

2002-2003 impacts environmental:
crops damaged
pine forest damaged

2002-2003 impacts economic:
tourist resorts affected
damage to business
crops =livelihood