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

earth science Flashcards

(65 cards)

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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
name some examples of: physical weathering
raining then freezing into cracks (frost/ice wedging) tree roots growing rain sudden change in temperature
26
fossil
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.
27
geologist
scientist who studies the Earth
28
hotspots
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
igneous rock
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
innercore
the innermost layer of the Earth --- the innercore is a solid mixture of iron and nickel at extreme temperatures and pressure
31
lava
liquid molten rock exposed to the surface of the Earth, outside of the volcano
32
magma
liquid molten rock beneath the Earth's surface in a magma chamber
33
mantle
the thickest layer of Earth, between the core and crust. It is made of solid and is partially melted.
34
Lithosphere
the crust and upper-part of the mantle
35
melting
a change of state from solid to liquid
36
metamorphic rock
any that has been changed by extreme pressure and heat --- this heat changes their crystals structure and minerals
37
mid-ocean ridge
an underwater mountain system where new oceanic crust forms
38
mineral
a natural substance usually found as crystals within rocks
39
mitigation
an action that decreases the harmfulness of an event
40
natural disaster
An event in the natural world that causes death or destruction
41
natural hazards
An event in the natural world that endangers living things : volcanoes, tsunamis, earthquakes, landslides-
42
ocean trench
A deep valley in the ocean at a convergent boundary when a plate subducts
43
oceanic crust
The crust that lies underneath the ocean and is 5 - 10km thick and denser than continental
44
outercore
the layer of earth that lies between the mantle and innercore - liquid mixture that generates Earth's magnetic field
45
parent rock
the original rock before a metamorphic is formed
46
plate boundary
the border between two tectonic plates
47
pressure
the amount of force applied to a certain area of the Earth
48
relative dating
a method to determine whether a rock is older or younger than another --- lower = older
49
rift valley
a long depression formed when divergent boundaries occur
50
rock cycle
the set of changes that turn one rock into another
51
seafloor spreading
the formation of new oceanic crust at a mid-ocean ridge.
52
sediment
small rock fragments such as mud, sand or gravel.
53
sedimentary rock
any rock that is formed when weathering, erosion, deposition, compaction and cementation occur --- can also be made from fossil remains
54
solidification
the change of state from liquid to solid
55
subduction
the sinking of one tectonic plate beneath the other
56
supercontinent
a single landmass made up of smaller continents joined together - PANGAEA
57
tectonic plate
a section of the crust and upper mantle - the lithosphere which is broken up into pieces and move differently because of the mantle
58
transform boundary
where two plate slide past each other along faults and pressure is built up because they are rigid. They trigger earthquakes
59
tsunami
A large ocean wave caused by an earthquake or coastal landslide
60
volcanic eruption
The release of magma from the magma chamber, erupting through a volcano
61
weathering
the breakdown of rocks into small grains, sediment and soil
62
How can earthquake geologists use sedimentary rocks to date back when earthquakes occur?
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
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?
Quartz is harder than Granite and is harder than 6.5 as well
64
what are the natural hazards caused by volcanoes
lahar, lava, volcanic ash, volcanic gas, pyroclastic flows
65
what is the K-T boundary?
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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