Enquiry Question 1 - Key Idea 1 Flashcards
The coast and wider litoral zone has distinctive features and landscapes.
1
Q
What is Enquiry Question 1?
A
Why are coastal landscapes different and what processes cause these differences?
2
Q
Globally, how many people live near coasts that are at risk of flooding?
A
1 billion
3
Q
How much of the world’s population live within 200km of the coast?
A
One half
4
Q
How are coasts dynamic:
A
- Coasts represent a boundary zone where land and sea meet, and where marine and terrestrial processes operate and interact
- Coasts experience extreme events which can cause significant rapid change.
- Human development on coasts is varied and constantly changing.
5
Q
Examples of human development on coasts:
A
- ports and transport,
- industrial locations
- residential and tourism land uses
6
Q
The litoral zone can be divided into:
A
a number of subzones
7
Q
What is the litoral zone:
A
The wider coastal zone including adjacent land areas and shallow parts of the sea just offshore
8
Q
Name the subzones of the litoral zone:
A
- backshore
- foreshore
- nearshore
- offshore
9
Q
Backshore
A
The cliff or sand dunes, plus the upper beach closest to the land. Only affected by waves during high tides (spring tides) or major storms.
10
Q
Foreshore
A
The lower part of the beach which is covered twice a day at high tide; receives the most regular wave action
11
Q
Nearshore
A
The section of the littoral zone between the low tide level and the deeper offshore water
12
Q
Offshore
A
The section of the littoral zone that consists of deeper water in which waves maintain their shape and speed, furthest from the land.
13
Q
Berm
A
The shingle ridges often found towards the back of a beach
14
Q
Breakers
A
As waves come closer to shore they break, forming a foamy, bubbly surface
15
Q
Surf Zone
A
Zone of breaking waves
16
Q
Bar
A
Elongated sand body created by tidal currents or waves
17
Q
Lithology
A
The type of rock
18
Q
2 main types of coast:
A
Rocky (or cliffed) coastlines
Coastal plains
19
Q
Description of Rocky (cliffed) coastlines:
A
- Cliffs varying in height from a few metres to hundreds of metres;
- cliffs are formed from rock but the hardness of the rock is very viable
- transition from land to sea is abrupt
- at low tide, foreshore zone is exposed as a rocky, wave-cut platform
- cliffs are vertical but cliff angles can be much lower
- cliffs made up of igneous, granite, basalt and compacted older sedimentary rocks
20
Q
Coastal plains: / (alluvial coasts)
A
- Sandy coastlines
- Estuarine coastlines
The land gradually slopes towards the sea across an area of deposited sediment, with sand dunes and mud flats being the most common examples.
21
Q
Description of Sandy coastlines:
A
- at high tide, sandy beach is inundated but vegetated dunes are not
- dune vegetation plays crucial role in stablising coast and preventing erosion
- sand dunes frindge the coastline
- younger, weaking sedimentary rocks, e.g chalks, clays and sandstone.
22
Q
Description of estuarine coastlines:
A
- gradually transitions from land to sea
- estuaries found at mouth of river
- extensive mudflats, cut by channels are exposed at low tide but inundated at high tide
- closer to backshore, the mud flats are vegetated, forming a salt marsh
- low energy environment
23
Q
How much of the UK coastline consists of cliffs:
A
1000km
24
Q
Example of cliffed coast:
A
Chalk cliffs at Flamborough Head in Yorkshire
25
Example of estuarine coastline:
Lymington in Hampsjore
26
Rocky coasts are a result of:
Result of resistant geology (withstand erosive forces of sea, rain and wind)
27
Where are rocky coasts found?
In high energy environments
28
Where are Coastal plain landscapes found?
Near areas of low relief and often in a low energy environment
29
Coastal plain landscapes are a result from:
Result from supply of sediment from different terrestrial and offshore sources.
30
Cliff profiles:
The height and angle of a cliff face as well as its features, such as wave-cut notches or changes in slope angle.
31
Contrasting coastlines:
Primary vs Secondary
Emergent Vs Submergent
Microtidal vs Mesotidal vs Macrotidal
Low energy vs High energy
32
Primary coasts are dominated by:
land based processes such as deposition at the coast from rivers or new coastal land formed from lava flows
33
Secondary coasts are dominated by:
marine erosion or deposition processes
34
Emergent coasts:
where the coasts are rising relative to sea level, e.g due to tectonic uplift
35
Submergent coasts:
are being flooded by the sea, either due to rising sea levels and/or subsidising land
36
Submergent coastlines are formed when:
When sea levels rise (e.g due to climate change or post glacial melt), low lying coastal plains are submerged
37
Microtidal coasts:
Tidal range of 0-2m
38
Mesotidal coasts:
Tidal range of 2-4m
39
Features of low energy coasts:
- sheltered
- limited fetch
- low wind speeds
- small waves
40
Features of high energy coasts:
- exposed
- facing prevailing winds
- long wave fetches
- powerful waves
41
Dynamic equillibrium
Coastal processes vary but landform formation is continous and stays the same
42
Coastal plain landscapes are a result from:
Result from supply of sediment from different terrestrial and offshore sources.
43
Strata
The different layers of rock within an area and how they relate to each other
44
Examples of sub-aerial processes:
- weathering
- mass movement
- surface run off
45
Weathering -
the chemical, biological and mechanical breakdown of rocks into smaller fragments and new minerals in situ
46
Mass movement -
landslides, slumps and rock falls, all of which move material downslope under the influence of gravity
47
Surface run off -
water, usually during heavy rain, flowing down the cliff face and causing erosion of it
48
Sub-aerial processes are more influential when cliffs are made of:
less resistant rock such as shale, clay or mudstone
49
Resistance refers to:
the 'hardness' of rock
50
Resistance is influenced by:
- how reactive minerals in the rock are when exposed to chemical weathering
- whether rocks are clastic or crystalline. Crystalline are more erosion resistant
- the degree to which rocks have cracks, fractures and fissures, which are weaknesses exploited by the forces of weathering and erosion
51
Where is calcite found and what is it weathered by?
In limestone.
By solution
52
Where is quartz found and what is it weathered by?
In sandstone.
Not subject to chemical weathering
53
Clastic rocks:
Sedimentary rocks like sandstone, made of cemented particles
54
Crystalline rocks:
Igneous and metamorphic rocks, made up of interlocking crystals.
55
Coastal accretion:
The deposition of sediment at the coast, and the seaward growth of the coastline, creating new land.
- Often involves sediment deposition being stabilised by vegetation
56
Dynamic equillibrium
The balanced state of a system when inputs and outputs balance overtime. If one element of the system changes because of an outside influence, the internal equillibrium of the system is upset and other components of the system change. By a process of feedback, the system adjusts to the change and the equillibrium is regained.
57
What are coastal plains:
Low lying, low relief areas close to the coast
- Contain wetlands and marshes because they are only just above sea level and poorly drained due to the flatness of the landscape
58
Coastal plains can form in one of two ways:
1. Some (e.g Atlantic coastal plain in USA) are a result of a fall in sea level, exposing seabed of what was once a shallow continental shelf sea.
2. Deposition of sediment from the land, brought down to the coast by river systems, can cause coastal accretion where the coastline gradually moves seaward, such as in river delta.
59
Why are coastal plains described and a dynamic equilibrium?
As there is a balance in the forces of
- deposition of sediment from river systems inland and deposition of sediment from offshore and longshore sources
- erosion by marine action at the coast
60
How are caves formed?
Erosion of weakened rock along faults
61
How are arches formed?
Where two caves on either side of a headland join up
62
How are wave cut notches formed?
Erosion of weak rock as cliff base
63
How are stacks and stumps formed?
Pillars either fault bounded or made of more resistant rock
64
Describe the essential features of backshore (3)
- A part of the beach above normal high tide mark, at cliff base.
- Only effected by the sea during exceptionally high tide and storms. -- Consists of features like storm beaches, pebbles and berms
65
Describe the essential features of foreshore (3)
- Lower beach, intertidal or surf zone.
- An area with a high water mark and a low water mark.
- This area is most important for marine processes in times influenced by waves and by storms.
66
Describe the features of nearshore (2)
- Shallow water close to the tide line but covered by water at normal low tides.
- The zone in which waves usually brake.
67
Describe the features of offshore (3)
- The point beyond the influence of waves where there is little to no impact of the sea bed.
- Activity in this areas is limited to deposition of sediment.
68
What causes waves?
Waves are most commonly caused by wind. Wind-driven waves, or surface waves, are created by the friction between wind and surface water (frictional drag). As wind blows across the surface of the ocean or a lake, the continual disturbance creates a wave crest. The gravitational pull of the sun and moon on the earth also causes waves.
69
What is shoaling?
Process that decreases water depth-
It occurs as waves enter the shallow water, the wave speed and wave length decrease in shallow water, therefore the energy per unit area of the wave has to increase, so the wave height increases.
70
Formation of bays:
Disconcordant coastlines have headlands which are consisting of hard, resistant rock such as granite, and have very slow rates of erosion. They also consist of alternating layers of less resistant rock such as sandstone which is more easily eroded. The softer rock is eroded, leaving the hard bands of rock uneroded, forming a bay.
71
What is long shore drift?
The transportation of sediment along the coast by action of the waves, often in the same direction of the prevailing winds. where waves approach the coast at an angle, the swash of the breaking wave is directed diagonally up the beach.
However, the backwash of the returning water runs directly down the beach and a right angle under the force of gravity
72
What are the inputs to the coastal system?
- Marine (waves tides storm surges)
- Atmospheric (weather climate solar energy)
- Land (rock type and structure tectonic activity)
- People (human activity coastal management)
73
Two long term criteria to classify coasts:
- geology
- sea level change
74
Geology:
all the characteristics of land, including lithology (rock type) and structure (arrangement of rock units) - can be used to classify coasts as rocky, sandy or estuarine or concordant/discordant
75
Sea Level Change:
used to classify coasts as emergent or submergent. This can be caused by:
Tectonic processes can lift sections of land up, causing local sea fall, or lead sections of land to subside, causing local sea rise.
Climate change causes sea levels to rise and fall in a 100,000 year cycle due to the change in the Earth's orbit shape.
sea levels fall for 90,000 years during glacials as ice sheets expand and rise for 10,000 during interglacials
sea levels rise even more when the Earth emerges from an ice age and all surface ice melts
76
What are the SHORT TERM criteria to classify coasts:
- Energy inputs
- Sediment inputs
- Advancing/ retreating
77
Energy Inputs
Coasts receive energy inputs from waves (main input), tides (ebb and flow over a 12.5 hour cycle), currents. rivers, atmospheric processes, gravity and tectonics.
Used to classify coasts as high energy and low energy.
78
Sediment Inputs:
Coasts receive sediment inputs from waves and wind (vary constantly with weather), tides (ebb and flow over 12 1/2 hour cycle), currents, mass movement and tectonic processes. Sediment is added to a coastline through deposition and removed by erosion.
Where erosion > deposition there is a net loss of sediment and the coastline retreats -- an eroding coastline.
Where deposition > erosion there is a net gain of sediment and the coastline advances -- an outbuilding coastline.
