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SCIENCE STUDY 2024 - 8TH GRADE > earth science > Flashcards

earth science Flashcards

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1
Q

What is a rock?

A

A natural substance made when geological processes occur. It is composed of solid crystals or different minerals.

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2
Q

cementation, what is it and what does it do?

A

The gluing together
of sediment by new
mineral crystals —
Cementation can cause sediment
grains to stick together, forming
sedimentary rock.

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3
Q

compaction - what is it and what does it do?

A

The squeezing of sediment by
the weight of overlying layers —
Compaction can cause sediment
grains to stick together, forming
sedimentary rock.

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4
Q

continental crust

A

Crust that lies beneath a
continent —
Continental crust is about
25–70 km thick and is less dense
than oceanic crust.

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5
Q

continental drift

A

The movement of continents
around the surface of Earth —
Continental drift theory was
proposed by Alfred Wegener in
1912 but was widely accepted
only in the 1960s.

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6
Q

what causes continental drift?

A

divergent boundaries

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7
Q

convergent boundary

A

A place where two tectonic
plates move towards
each other —
At convergent boundaries,
mountain ranges, ocean trenches
and volcanoes can form.

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8
Q

the process of convergent boundaries: oceanic-oceanic

A

oceanic-oceanic: the plate subducts beneath the other, making a trench, and sinks into the mantle to melt into magma. This magma then rises to the weakened part of the plate to form underwater volcanoes

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9
Q

the process of convergent boundaries: continental - oceanic

A

convergent - oceanic: the oceanic crust which is denser, subducts beneath the continental crust, creating a trench where the oceanic sinks into the mantle to form magma. This magma also makes volcanoes with eruptions.

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10
Q

What are the properties of rock?

A

Cleavage, hardness, lustre, streak, colour

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11
Q

What are crystals?

A

Most crystals are minerals made up of a crystalline structure.

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12
Q

divergent boundary

A

A place where two tectonic
plates move away from
each other—
At divergent boundaries, rift
valleys and mid-ocean ridges
can form.

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13
Q

the process of divergent boundaries:
oceanic-oceanic

A

Two oceanic plates separate and make a mid-ocean ridge. The plate is also weakened, allowing magma to seep through

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14
Q

the process of divergent boundaries:
continental- continental

A

Two plates made up of continental crust split and create a rift-valley. The plates are both weakened allowing magma to rise through and form a volcano.

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15
Q

What happens to a rift-valley overtime?

A

Rift valleys are formed from divergent boundaries and overtime, water rises through to become a mid-ocean ridge. This turns into a basin and magma rises through to make an underwater volcano. While all of this is taking place, it expands the oceanic crust

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16
Q

What is the relationship of crust and plate tectonics.

A

The theory of plate tectonics states that Earth’s surface is broken up into rigid slabs of rock. These are called tectonic plates.

The plates are made up of the crust and the solid upper layer of the mantle. Taken together, these are known as the lithosphere.

The lithosphere sits on a layer of the mantle that is partially melted. This semi-liquid layer allows the plates to move horizontally, carrying the continents with them.

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17
Q

crust

A

The outermost layer of the earth - part of the lithosphere

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18
Q

transform boundaries

A

A place where two tectonic
plates slide past each other
At transform boundaries,
earthquakes often occur as
pressure along faults is suddenly
released.

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19
Q

earthquake

A

The sudden shaking of
Earth’s surface —
An earthquake is a natural hazard
that occurs when two slabs
of rock suddenly slip against
each other.

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20
Q

erosion

A

The wearing away and
removal of rock —
Eroded sediment is transported
by wind, water or ice.

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21
Q

chemical weathering

A

When rocks are changed in their substances or they are broken down by chemicals

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22
Q

Why do different rocks weather at different rates?

A

their hardness

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23
Q

Physical weathering

A

weathering that occurs physically and breaks down rocks into small fragments

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24
Q

name some examples of :
chemical weathering

A

CO2 + Water = carbonic acid
Iron + Oxygen = iron oxide (rust)
acid rain

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25
Q

name some examples of: physical weathering

A

raining then freezing into cracks (frost/ice wedging)

tree roots growing

rain

sudden change in temperature

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26
Q

fossil

A

The remains or traces of an
ancient organism preserved
in rock — Fossils provide information about
how life evolved and how Earth’s surface has changed.

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27
Q

geologist

A

scientist who studies the Earth

28
Q

hotspots

A

An unusually hot part of the
mantle where volcanoes
can form — At hotspots, magma can rise
through the crust to form
volcanoes, even away from
plate boundaries.

29
Q

igneous rock

A

Any rock - formed by the cooling of magma and lava and can be porphyritic, aphanitic and have vesicular texture. There are two types: intrusive/extrusive

30
Q

innercore

A

the innermost layer of the Earth — the innercore is a solid mixture of iron and nickel at extreme temperatures and pressure

31
Q

lava

A

liquid molten rock exposed to the surface of the Earth, outside of the volcano

32
Q

magma

A

liquid molten rock beneath the Earth’s surface in a magma chamber

33
Q

mantle

A

the thickest layer of Earth, between the core and crust. It is made of solid and is partially melted.

34
Q

Lithosphere

A

the crust and upper-part of the mantle

35
Q

melting

A

a change of state from solid to liquid

36
Q

metamorphic rock

A

any that has been changed by extreme pressure and heat — this heat changes their crystals structure and minerals

37
Q

mid-ocean ridge

A

an underwater mountain system where new oceanic crust forms

38
Q

mineral

A

a natural substance usually found as crystals within rocks

39
Q

mitigation

A

an action that decreases the harmfulness of an event

40
Q

natural disaster

A

An event in the natural world that causes death or destruction

41
Q

natural hazards

A

An event in the natural world that endangers living things : volcanoes, tsunamis, earthquakes, landslides-

42
Q

ocean trench

A

A deep valley in the ocean at a convergent boundary when a plate subducts

43
Q

oceanic crust

A

The crust that lies underneath the ocean and is 5 - 10km thick and denser than continental

44
Q

outercore

A

the layer of earth that lies between the mantle and innercore - liquid mixture that generates Earth’s magnetic field

45
Q

parent rock

A

the original rock before a metamorphic is formed

46
Q

plate boundary

A

the border between two tectonic plates

47
Q

pressure

A

the amount of force applied to a certain area of the Earth

48
Q

relative dating

A

a method to determine whether a rock is older or younger than another — lower = older

49
Q

rift valley

A

a long depression formed when divergent boundaries occur

50
Q

rock cycle

A

the set of changes that turn one rock into another

51
Q

seafloor spreading

A

the formation of new oceanic crust at a mid-ocean ridge.

52
Q

sediment

A

small rock fragments such as mud, sand or gravel.

53
Q

sedimentary rock

A

any rock that is formed when weathering, erosion, deposition, compaction and cementation occur — can also be made from fossil remains

54
Q

solidification

A

the change of state from liquid to solid

55
Q

subduction

A

the sinking of one tectonic plate beneath the other

56
Q

supercontinent

A

a single landmass made up of smaller continents joined together - PANGAEA

57
Q

tectonic plate

A

a section of the crust and upper mantle - the lithosphere which is broken up into pieces and move differently because of the mantle

58
Q

transform boundary

A

where two plate slide past each other along faults and pressure is built up because they are rigid. They trigger earthquakes

59
Q

tsunami

A

A large ocean wave caused by an earthquake or coastal landslide

60
Q

volcanic eruption

A

The release of magma from the magma chamber, erupting through a volcano

61
Q

weathering

A

the breakdown of rocks into small grains, sediment and soil

62
Q

How can earthquake geologists use sedimentary rocks to date back when earthquakes occur?

A

Earthquake geologists can look at the sedimentary layers of the rock and the layers that got affected by the earthquake are older and the earthquake is younger than them

63
Q

Using the Mohs hardness scale which is a scale from 1-10, Granite is 6.5 on the scale. Quartz is able to scratch Granite and leave a mark, what does this suggest?

A

Quartz is harder than Granite and is harder than 6.5 as well

64
Q

what are the natural hazards caused by volcanoes

A

lahar, lava, volcanic ash, volcanic gas, pyroclastic flows

65
Q

what is the K-T boundary?

A

The K-T boundary is a layer of sedimentary rock which has shocked quartz and a high level of iridium.

SCIENCE STUDY 2024 - 8TH GRADE (7 decks)

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