Coasts Flashcards
(93 cards)
1
Q
How is a wave formed
A
Friction occurs between air and water. Water particles move in a circular motion. Air pressure and friction creates waves.
2
Q
What is a sediment cell?
A
A coastline that is self-contained. Closed system bounded by headlands. There is erosion, deposition and transport of sediment. Inputs from sea , land or river. Human activity can interrupt the distribution.
3
Q
What is a discordant coastline?
A
Where the types of rock alternate along the coastline creating headlands and bays
4
Q
What is a concordant coastline?
A
Where rocks lie parallel to the coastline
5
Q
What is a swell?
A
Swell are waves that originate offshore
6
Q
What is a neap tide?
A
When the moon and the sun are at 90 degrees with the earth. The lowest of low tides
7
Q
What is a spring tide?
A
A tide just after the full moon, when there is the greatest difference between high and low tide.
8
Q
What is long-shore drift?
A
The gradual movement of sediments along a coastline, with waves striking at an angle , and retreating perpendicular with the backwash
9
Q
What is mass movement?
A
The downhill movement of weathered material due to gravity
10
Q
What is a simple spit?
A
A straight spit that grows out roughly parallel to the coast
11
Q
What is a compound spit?
A
A spit that has multiple recurved hooks , resulting from several periods of growth
12
Q
What is a sand-bar?
A
An area of sand that sits above the water, connecting the shoreline
13
Q
How is a sandbar formed?
A
A sandbar is formed when a spit grows the whole way across the bay
14
Q
What is isostatic change?
A
When the land rises or falls relative to the sea at a local scale
15
Q
What is eustatic change?
A
A global change in sea level change resulting from an actual fall or rise in the level of the sea itself
16
Q
What is a submergent coastline?
A
Where the ocean has overtaken previously low lying areas
17
Q
What are the landforms of submergent coastlines?
A
Rias, Fjords, Estuaries
18
Q
How are Rias formed?
A
Rias form when sea levels rise and flood V-shaped river valleys. The valley was eroded by rivers before being drowned. This creates a wide, deep inlet with gentle sides.
19
Q
How are fjords formed?
A
Formed primarily by glacial erosion (abrasion and plucking).
Glaciers carve out glacial troughs as they moved toward coastal areas , (downwards) - carving out a valley
Isostatic readjustment (local) and eustatic sea level rise (global) led to their flooding. (due to meltwater)
Formed during interglacial periods.
20
Q
How are estuaries formed?
A
Created by rising sea levels flooding river mouths
21
Q
What is an emergent coastline?
A
When a fall in sea level exposes land previously covered by the sea
22
Q
What are the different landforms of emergent coastlines?
A
Raised Beaches, Marine platforms, caves
23
Q
How are raised beaches formed?
A
They form when tectonic forces uplift coastal areas, lifting former shorelines above the reach of the sea
24
Q
How are marine platforms formed?
A
They form through the process of erosion, where waves continually pound against the base of coastal cliffs, gradually wearing away
25
How is a wave cut platforms/wave cut notches formed?
When the sea attacks a weakness at the base of the cliff, causing an undercut
26
What are the sequences in coastal erosion?
Discordant coastline/Concordant coastline=> Headland=> crack=> cave=> arch=> stack=> stump
27
What are the types of erosion?
Hydraulic action, abrasion, attrition and solution
28
What is hydraulic aciton?
When waves hit/pound the shore
29
What is abrasion?
When pebbles grind along a rock platform, and sediment in waves are thrown against the cliff-face
30
What is attrition?
Where rocks/materials are carried by water and collide breaking down into smaller pieces
31
What is solution?
Where rocks are dissolved in water/chemically
32
What are the types of weathering?
Physical, Chemical , Biological
33
What is freeze-thaw weathering?
Water enters cracks in rocks, freezes , expands and causes the rock to break apart
34
What is hydrolysis?
Water reacting with rocks causing it to dissolve
35
What is a tombola?
a bar of sand or shingle joining an island to the mainland.
36
What are the 4 types of mass movement?
Rock fall, landslide, mudslide and slumping and sliding
37
What causes mass movement?
Cliffs being made out of soft rock ( boulder clay) being highly susceptible to erosion and weathering . Also caused by sub-aerial processes such as precipitation
38
What is a marine platform?
Rock base of eroded cliffs that extends as cliffs retreat
39
What is isostatic re-adjustment?
When the land rises due to ice melting, which was weighing the land down before
40
What is a relict cliff?
A relict cliff is an old cliff that used to be at the coastline but is now found inland due to changes in sea level or land uplift
41
What is an example of a raised beach?
Isle of Arran
42
How is precession affecting Eustatic change?
Due to sea level changing due to the earth's rotation, influencing melting of ice and global sea temperatures.
43
What are the different sub-aerial processes and how do they affect the coastline?
Biological, Chemical and Physical weathering and mass movement
Freeze thaw- weakens cliff faces
Solution- affects clay and mass movement
44
How are compound spits made?
LSD moves sediment along the coast, depositing it until the mainland ends to form a spit, which can develop a recurved hook if secondary winds shift the angle of deposition
Waves refract around the end of the spit, bending it to form recurved hooks.
45
What is Long-shore drift?
Longshore (littoral) drift is the movement of material along the shore by wave action. It happens when waves approach the beach at an angle
46
Outline the development of a salt-marsh
Occurs in low lying energy environments/ behind rivers and estuaries. Mud is deposited by river and tide=> Colonised by vegetation=> building up mud / nutrients
47
Explain how sand dunes are formed?
Sand dunes form when onshore winds transport sand above the high-water mark, where vegetation like marram grass traps and stabilizes the sand, allowing dunes to grow over time, develop richer soils, and support diverse plant species that further anchor and protect the dunes.
48
What are negative feedback loops within coasts?
(Destructive waves)=> Sediment eroded/ deposited offshore, forming offshore bar, waves break before reaching beach, storm calms, conditions return to dynamic equilibrium
49
What are positive feedback loops within in coasts?
Groynes/Erosion. Groynes interrupt the sediment supply => Increasing erosion rate.
Erosion can be self-enhancing due to weaking coastal material
50
What factors affect a coastal landscape?
weathering, transportation, deposition, erosion.
51
What is a shingle
a mass of small rounded pebbles, especially on a seashore.
52
What is the role of marram grass in sand dunes?
Marram grass traps sand, stabilizes dunes with deep roots, and helps colonize harsh environments, protecting dunes from erosion.
53
What are coastal landforms caused by deposition?
bars, spits, beaches
54
What is a barrier beach?
A barrier beach is a long, narrow landform that runs parallel to the coastline, separated from the mainland by a body of water such as a lagoon, bay,
55
How is a barrier beach formed?
It is formed by the accumulation of sand and sediment due to wave action and longshore drift. Spit goes along a bay forming a lagoon behind
56
What coastal landscapes are formed by weathering?
Cliffs & wave cut notches, caves , arches , stacks , stumps
57
What is a rip current?
A rip current is a strong, narrow flow of water that rushes from the shore out to sea.
It forms when waves break strongly on the shore and the water has to escape back out. Instead of flowing evenly, it funnels through a low spot or gap in a sandbar, creating a fast-moving current.
58
How much will sea levels rise by 2100?
30cm
59
What is the importance of mangroves?
-Method of soft engineering (protects against coastal erosion)
-Used for timber and wood
-Fisheries ( also habitats)
-Climate regulation
-Water quality maintenance
60
How are simple spits made?
Sediment is moved along the coast by LSD
When the coastline suddenly changes direction (like at a river mouth), sediment gets deposited into open water.
sediment builds out into the sea, creating a long, narrow ridge.
The end of the spit may curve if waves or wind change direction.
Behind the spit, calm water can lead to mudflats or salt marshes forming.
61
What are the benefits of using hard engineering?
prevention of soil erosion, stabilizes beaches , acts as flood defences
62
Negatives of hard engineering?
Expensive, interferes with natural deposition, long term degradation of beaches./ shift supply of sediment
63
What are the positives of soft engineering?
Environmentally friendly , cost effective , improves habitat
64
What are the negatives of soft engineering?
Less effective in harsh conditions, maintenance ,
65
What are low energy coastal processes?
Deposition
66
What are high energy coastal processes?
Erosion and transportation
67
What is wave rarefaction?
the change in direction of a wave as it travels from one medium to another, where the speed of the wave changes, as it moves into shallower water
68
What are the causes of eustatic change?
Melt water from glaciers, causing global change, due to thermal expansion, or changes in seafloor due to tectonic processes. Causes changes in the volume of water
69
What are causes of isostatic change?
glacial activity (glacial isostacy) , tectonic activity- which causes changes in the land level
70
What are the causes of glacial isostasy?
Glacial isostasy is the slow rising of land that was previously compressed under the weight of ice sheets during an ice age.
71
What are low energy environments in coasts?
Salt marshes , mudflats , estuaries , lagoons
72
What are high energy environments in coasts?
Rocky coastlines , erosional landforms , strong wave action
73
What are erosional landforms in coasts?
cliffs, wave-cut notch, wave-cut platform, caves , arches , stacks , stumps
74
What are depositional landforms?
beaches , spits, bars, tombolo's , salt marshes ,
75
What is transportation?
Transportation of beach sediment along coasts refers to the movement of sand, gravel, and other materials along shorelines due to natural processes like waves, currents, and tides. T
76
What is deposition?
deposition refers to the process where materials such as sand, silt, and pebbles are carried by the sea and deposited along the coastline
77
How is the process of a wave cut platform a negative feedback loop?
A wave-cut platform is a negative feedback loop because as it forms, it reduces wave energy reaching the cliff, which in turn slows further erosion.
78
Are constructive waves negative feedback loop or positive feedback loop?
Constructive waves are part of a negative feedback loop because as they deposit sediment and build up the beach, the beach becomes better at absorbing wave energy, which reduces further erosion and encourages more deposition.
79
Are destructive waves part of a positive feedback loop or negative?
Destructive waves are part of a positive feedback loop because they erode the beach, making it lower and steeper, which allows waves to hit with more force and cause even more erosion.
80
How is wind and tidal erosion the primary energy processes that drive erosion?
Wind moves sand and sediment along the shore (transportation).
Generates waves that crash against the coastline, causing wave erosion.
Rising and falling tides create tidal currents, eroding beaches and cliffs.
Longshore drift moves sediment along the coast, reshaping the shoreline.
81
What is a tidal current?
The horizontal movement of water caused by the rising and falling of tides.
Moves water in and out of coastal areas, contributing to erosion and shaping the coastline
82
How are arches made?
Rock Layers Form – Sedimentary rocks like sandstone are deposited
Joints Appear – Cracks form in the rock from stress or pressure changes.
Weathering and Erosion – Water, wind, and freeze-thaw widen joints and break down rock.
Fins Develop – Erosion isolates narrow walls of rock.
Holes Form – Weak spots in fins are eroded, creating openings.
Arch Expands – Erosion enlarges the opening until a full arch forms.
83
What are the different types of soft engineering?
Sand nourishment, managed retreat (coastal re-alignment), creating marshland, reprofiling, dune nourishment
84
To what extent rock type is the most significant factor in the formation of arches?
More resistant rocks (e.g. limestone) withstand erosion, allowing features like arches to form.
Less resistant rocks are eroded away early by marine processes
Sub-aerial weathering (e.g. chemical and biological weathering) also weakens rock
High-energy coastal environment is essential:
Destructive waves cause undercutting
Large fetch and strong winds enhance wave power
Deep water allows sustained wave motion
85
What 3 categories are the impacts of rising sea levels categorised into?
Flooding, damage to habitat and increased erosion
86
What is the difference between slumping and sliding in mass movement?
Slumping is when a mass of rock or soil moves down a slope in a curved, rotational motion, often along a concave surface. It typically occurs in saturated clay or weak rocks.
Sliding is when material moves quickly down a slope in a straight line, often along a flat surface, like a landslide of loose rocks or debris.
87
Outline the development of a salt marsh ?
Developed in sheltered area forms behind a spit or estuary – low wave energy.
Mudflats build up from deposited fine silt and clay (from waves). - providing nutrients
Pioneer species (e.g. eelgrass) colonise, trap more sediment.
Vegetation succession raises land level → mature salt marsh forms.
88
How does a mudflat become a saltmarsh?
A mudflat can become a salt marsh through a process of sediment deposition and plant colonization- increasing nutrient availability
89
Definition of mudflats?
Located on the edges of estuaries , low energy environments, deposition of fine sediment.
Located in sheltered areas (behind spits)
90
What is flocculation?
Flocculation is when tiny clay particles in freshwater clump together as they mix with saltwater, forming heavier particles that sink and settle (and stabilising), aiding deposition in estuaries. - bringing in nutrients to lead to succession
91
What is humus?
Humus is dark, organic matter in soil made from decomposed plant and animal material. It improves soil fertility and structure.
92
What plants colonise mudflatts?
Sea Purslane, Glasswort
93
How are mudflats formed?
They build up in sheltered coastal areas (like estuaries) where slow-moving water lets fine sediments (silt, clay, organic matter) settle. Tides keep adding layers, and over time, you get those wide, flat, muddy zones
