Final 3 Flashcards
(108 cards)
1
Q
The four layers of the Earth, in order of outside to in
A
Crust, mantle, outer core, inner core
2
Q
What is the crust?
A
Rocky outer layer; thin compared to other sections, 5-70km thick
3
Q
What is the mantle?
A
Semi-molten layer + 3,000km thick
4
Q
What is the inner core?
A
An extremely hot layer which is a very dense solid
4
Q
What is the outer core?
A
Liquid kayer + 2,000km thick
4
Q
What is a plate margin?
A
Where 2 or more plates meet
5
Q
What are convection currents?
A
Movement in Earth’s mantle caused by heat of the core
6
Q
The Earth’s crust is broken into slabs, what are they?
A
Plates
7
Q
Why are plates constantly moving?
A
Convection currents
8
Q
What is a constructive plate margin? / what are it’s characteristics?
A
- Occurs when plates move apart
- Volcanoes form as magma swells up to fill gap + new crust is formed
9
Q
Example of constructive plate margin
A
North American and Eurasian plates
10
Q
What is a destructive plate margin? / what are it’s characteristics?
A
- Occurs when plates move towards each other and collide
- Two types;-
1) 2 continental plates
COLLIDE and form fold mountains
2) Oceanic + continental plate
Oceanic plate sinks under continental plate + mantle.
Create earthquakes, fold mountains + volcanoes
11
Q
Examples of both types of destructive plate margins
A
1) continental x2 = Indiam + Eurasian plates
2) oceanic + continental = Nazca + Southtown American
12
Q
What is a conservative plate margin? / what are it’s characteristics?
A
- occurs when plates solidesa past each other in opposite directions
- friction is overcome + plates slide past in sudden movement. Shockwaves produce earthquake.
13
Q
What are volcanoes?
A
Vents to interior of planet
13
Q
Examples of conservative plate margins
A
North American + pacific plates
13
Q
What are the characteristics of a shield volcano?
A
- gently sloping sides
- runny lava
14
Q
What do volcanoes do?
A
Allow magma from mantle to spill out as lava
15
Q
What are the characteristics of a composite volcano?
A
- steep sided + cone shaped
- made by layers of ash + lava
- lava is sticky + doesn’t flow far
16
Q
What are earthquakes?
A
Sudden, violent shaking of the ground
17
Q
Why do earthquakes occur?
A
Because of friction, plates become stuck, pressure builds up and when released, sends out huge amount of energy
18
Q
Name for where an earthquake originates
A
Focus
19
Q
What are earthquakes’ energy released as?
A
Seismic waves
19
Q
Point on Earth’s surface directly above focus
A
Epicenter
20
What is the name for a tsunami in English?
Harbour wave
21
What is a tsunami?
Large sea wave caused by displacement of large volume of water
22
What can a tsunami be caused by?
Earthquakes moving sections of Earth’s crust under ocean
23
The ways to manage hazards (three Ps)
1) PREDICTION - use technology to estimate when and where earthquake happens (difficult to know exactly when)
2) PROTECTION - putting measures in place to protect people during earthquakes
Common strategy: building special buildings that won’t collapse (= aseismic)
3) PREPARATION - getting ready for earthquake
Special drills + practices so people know what to do + prepare materials in advance
24
What is geology?
Study of the earth
24
Other names for geology
Geoscience / earth science
25
What does geology look at?
How Earth is formed, it’s structure, composition and processes acting on it
26
How old is the Earth?
4.5 billion years old
27
What can we discover about Earth through studying geology?
We can unlock Earth’s past and anticipate it’s future
28
Rock types
igneous, sedimentary, metamorphic
29
What are igneous rocks?
Result from volcanic activity; lava erupts at constructive plate boundaries, it reaches the surface and cools + solidifies to form basalt.
30
Where can igneous rocks be found in Spain?
Canary Islands
31
What are extrusive rocks?
Rocks formed by lava cooling and solidifying at the surface
32
What are intrusive rocks?
Rocks formed by magma cooling and solidifying beneath the surface
33
How are intrusive rocks exposed?
By earth’s surface being weathered and eroded
34
Examples of extrusive and intrusive (igneous) rocks
Basalt = extrusive
Tonalite = intrusive
35
What are sedimentary rocks?
Made up of small particles of sand + rock which have been transported by wind, rivers and ice and have been deposited on lake/seabed
36
What happens over many years to sedimentary rocks?
Layers of sediment begin to accumulate. They are compressed by weight of deposits above and form sedimentary rocks.
37
What are the layers of sedimentary rock called?
Bedding planes
38
compressed sand
Sandstone
39
Compressed mud
Clay/shale/mudstone
40
Where do limestone and chalk come from?
Remains of dead organisms (plants, animals, marine species)
41
What are chalk and limestone rich in? What else do they contain?
Calcium carbonate and contain fossils
42
Sedimentary rocks suggest movement of continental globe, what theory explains this?
Plate tectonics
43
Aside from limestone, chalk, sandstone and clay, what are other examples of sedimentary rock?
Gypsum and siltstone
44
What are metamorphic rocks?
Igneous or sedimentary rocks that have been changed in shape and form by intense heat and pressure at plate boundary/fault line
45
What are examples of metamorphic rock?
Slates, schists, marble, phyllite, eclogite, skarn
46
What is suspension?
Small particles carried by water
47
What is solution?
Soluble materials dissolve in water and are carried along
48
What is traction?
Large particles are pushed along bottom of river bed/sea by force of sea
49
What is saltation?
pebble-sized particles are bounced along river bed/sea by force of water
50
What is the size and energy of a wave influenced by?
- how long wind has been blowing
- strength of wind
- how far wave has travelled (fetch)
51
Characteristics of a destructive wave
- destroys
- strong backwash
- weak wash
52
Characteristics of a constructive wave
- creates
- strong backwash
- weak backwash
53
General erosion processes
1) hydraulic action
2) abrasion
3) solution
4) attrition
54
What is hydraulic action?
Force of water breaks rock particles away from river channel/cliff
55
What is abrasion?
Eroded rocks rub against the channel/thrown against cliff— wearing it away
56
Steps of coastal erosional landforms (1st type)
1) weather weakens cliff top
2) sea attacks cliff base forming cut notch
3) notch size increases causing cliff to collapse
4) backwash carries rubble back to sea forming wave cut platform
5) process repeats + cliff continues to retreat
57
Steps of coastal erosional landforms (2nd type)
1) hydraulic action creates cracks in headland
2) over time, crack becomes deeper
3) crack creates cave. May eventually break through
4) Creates arch. Arch becomes bigger and collapses
5) leaves a stack. Erosion turn stack into stump.
58
Pros and cons of a breakwater
Pons:-
- long term
- beaches remain natural
Cons:-
- expensive
- unattractive
59
Pros and cons of a Rip-rap
Pros:-
- boulders are good at absorbing wave energy
Cons:-
- can easily be moved
- they need to be replaced
59
Pros and cons of groynes
Pros:-
- build up the beach
- cheap
Cons:-
- easily destroyed
- south beaches are deprived of sediment
60
Pros and cons of gabions
Pros:-
- cheap
- efficient
Cons:-
- cages rust
- short lifespan
61
Soft engineering vs hard engineering
Soft engineering works either the natural processes of coast
61
Hard engineering examples (coastal management)
Breakwater, groynes, gabions, rip-rap
62
What is beach replenishment?
Adding sand + sediment to beach from sea floor
63
Pros and cons of beach replenishment
Pros:-
- creates wider beaches
- protects from erosion and flooding
- looks natural
Cons:-
- taking materials can kill organisms
- very expensive
- has to be repeated
- could affect tourism
64
What is managed retreat?
Allowing a section of land to flood in order for plants to grow and therefore become a natural wave + flood barrier
65
Pros and cons of managed retreat
Pros:-
- creates new marshland habitats
- fairly cheap
- reduced flooding
Cons:-
- may cause conflict due to lost land
- could affect people’s lives
66
social reasons to protect coast
- job loss
- housing loss
- deaths
- water supplies are affected
67
Soft engineering examples (coastal management)
Beach replenishment + managed retreat
68
Economic reasons to protect coast
- tourism loss
- businesses on edge
- house prices fall
- floods damage farmland
69
Environmental reasons to protect coast
- ecosystems are affected as sea water has high salt content
- SSIs are threatened by erosion
70
What is a drainage basin?
Area of land a river gets its water from. It is defined by the watershed.
71
What is a watershed?
An imaginary line marking out the drainage basin
72
What is a river source?
Where the river starts, usually in an upland area
73
What is a tributary?
Small rivers which join to main river
74
What are interlocking spurs?
The river eroded vertically downwards creating V-shaped valleys
74
What is a confluence?
Point where two rovers join
75
Formation of deltas
1) Rivers are forced to slow down when they meet at sea/lake
2) material builds up and channel is blocked and is forced to split up
3) eventually material builds up so much that low lying areas called deltas form
75
Formation of meanders
1. **River bends start to form:**
In a river, water flows in a winding path rather than a straight line because of obstacles and variations in the riverbed.
2. **Erosion on the outside bend:**
The water flows faster on the outside of the bend. This causes erosion (wearing away) of the riverbank.
3. **Deposition on the inside bend:**
The water flows slower on the inside of the bend. This causes deposition (dropping of sediment), which builds up the inside bank.
4. **Meander formation:**
Erosion and deposition continue over time, making the bends in the river more pronounced and forming meanders.
5. **Meanders shift and grow:**
As the meanders develop, they slowly move downstream and become more exaggerated.
75
Process of creating a waterfall
1) river flows over area of hard rock followed by soft rock
2) soft rock is eroded quicker, creating a step
3) as water passes over step, it erodes more of the soft rock
4) A steep drop is created = waterfall
5) hard rock is undercut by erosion + collapses
6) collapsed rock is swilled around + helps to erode softer rock in plunge pool
7) overtime more collapses occur and waterfall retreats creating a gorge
76
Formation of an ox-bow lake
Erosion causes outside bends to become closer and river breaks through.
Deposition cuts off the meander, forming ox-bow lake
77
Physical causes of flooding
1) snow melting
2) geology - rocks are impermeable
3) relief - steep valley means rain can’t infiltrate and runs off quickly
4) prolonged rainfall - saturated soil
5) heavy rainfall - increased volume of water in river
78
Human causes of flooding
1) urbanization - impermeable surfaces (tarmac) —> water runs off
2) deforestation - trees intercept rainfall
79
what is a flood hydrograph?
Shows wether river has flooded
80
Peak rainfall
When rainfall is at it’s highest
81
Lag time
Time it takes for water to reach river
82
Pros and cons of dams + reservoirs
Pros:-
- store water
- hydroelectric power
- flow control
Cons:-
- very expensive
- flooding downstream
83
Pros and cons of channel straightening
Pros:-
- water moves more quickly
Cons:-
- flooding downstream due to faster water
84
Pros and cons of man-made levees
Pros:-
- river can hold more water
Cons:-
- catastrophic flooding of leves break
85
Pros and cons of flood warnings
Pros:-
- impact of flooding reduced
- evacuation
Cons:-
- don’t stop floods
- LEDCs lack access to radio
86
Pros and cons of preparation
Pros:-
- impact of flood is reduced
- people know what to do
Cons:-
- Does not mean safety
- Expensive to modify buildings
87
Pros and cons of flood plain zoning
Pros:-
- risk of flooding is reduced
- impermeable surfaces not created
Cons:-
- limited urban expansion
- no help in places already built on
88
Backwash
Water from retreating wave heading back towards ocean
89
Breaker
Rush of water that tumbles off wave’s crest
90
Chop
Collection of small waves that give water a rough surface
91
Crest
Highest point of wave
92
Fetch
Distance wind blows over stretch of ocean without obstacles, used to determine wave height
93
Shoreline
Region where water meets land at beach
94
Swash
Layer of water that washes onto beach
95
Swell
Series of regular waves created by fetch (smooth + regular crests)
96
Trough
Wave’s largest point
97
Wavelength
Distance between two waves
