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C2 chemistry > The structure of the earth > Flashcards

The structure of the earth Flashcards

1
Q

what is on the outside layer of our earth?

A

a rocky crust

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2
Q

what is the outer layer of the earth made from?

A

tectonic plates

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3
Q

how fast do tectonic plates move?

A

very slowly

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4
Q

where are tectonic plates found?

A

on the outer layer of our earth

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5
Q

what does the movement of tectonic plates cause?

A

earthquakes and volcanoes at the plate boundaries`

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6
Q

how long has it took continents to move apart?

A

millions of years

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7
Q

what is the outer layer of the earth called?

A

the lithosphere

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8
Q

what makes up the lithosphere?

A

the crust and part of the mantle

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9
Q

explain what the lithosphere is?

A

relatively cold and rigid

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10
Q

finish this sentence… The tectonic plates that make up the earth’s crust is less dense than what

A

the rest of the mantle below

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11
Q

why has the theory of plate tectonics been accepted?

A

it explains the evidence. It has been tested and the results discussed by many scientists

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12
Q

can we drill through the crust?

A

no

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13
Q

how do we judge the thickness of layers in our earth?

A

by the use of seismic waves produced by earthquakes and by artificial explosions

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14
Q

explain what the lithosphere is?

A

rigid and brittle

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15
Q

what is the lithosphere divided into?

A

tectonic plates

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16
Q

what is the semi-rigid layer called?

A

the asthenosphere

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17
Q

explain the asthenosphere

A

it is hotter and like plasticine, which can flow even though its a solid

18
Q

how is energy through the earth’s core transferred towards the surface?

A

by convection currents in the mantle. These convection currents slowly move the plates

19
Q

what directions can tectonic plates move?

A

apart, collide, scrape past eachother

20
Q

which is more dense continental or oceanic?

A

oceanic

21
Q

what are the two types of plates?

A

continental and oceanic

22
Q

where can we find continental and oceanic plates?

A

oceanic accumulate on top where oceanic plates float higher in the mantle

23
Q

what is subduction?

A

where the oceanic plate sub ducts under the continental

24
Q

what causes an earthquake?

A

when the sinking plate descends, it may get stuck and then suddenly move

25
Q

what happens further down?

A

it partially melts to form magma

26
Q

how are volcanoes formed?

A

magma working its way up to the surface creating a chain of valcanoes on the edge of the plate

27
Q

How is igneous rock formed?

A

when magma cools and solidifies

28
Q

how are small crystals formed in igneous rock?

A

when it cools rapidly close to the surface

29
Q

how are large crystals formed in igneous rock?

A

when it cools slowly further from the surface

30
Q

what is lava

A

molten rock that reaches the surface of the earth from volcanoes

31
Q

how can you tell a safe volcano form an unsafe volcano?

A

if the lava is runny it is safe. If it is thick and sticky then an eruption can be explosive

32
Q

why do some people live near volcanoes?

A

because the ash makes a rich soil that is good for growing things

33
Q

why does magma rise through the earth’s crust?

A

because it is less dense than the crust

34
Q

what was the theory called that meant all continents wear joined at one point

A

the continental drift theory

35
Q

who suggested this theory?

A

Alfred wegner

36
Q

why was his theory not accepted?

A

no one could explain how the continents were able to move through the rocks of the ocean floor

37
Q

why was his theory accepted later?

A

because geologists found a huge ridge in the middle of the Atlantic ocean

38
Q

what does this prove?

A

that the sea floor is spreading outwards at this point. This is where plates are being formed

39
Q

what are subduction zones?

A

where plates are being destroyed

40
Q

explain iron-rich magma?

A

tends to be runny so if it spills people can get away (safe)

41
Q

explain silicia- rich magma?

A

forms rhyolite if it cools rapidly and is less runny

42
Q

what causes explosive volcanoes?

A

when dissolved gases in the magma have no time to escape the stiff liquid. The magma erupts like spray. It shoots out as clouds of searingly hot ash and pumice

C2 chemistry (12 decks)

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