1
Q
positive feedback
A
exacerbates the original change, pushing the system further from equilibrium. e.g erosion leads to mass movement which exposes cliff face more to erosion
2
Q
negative feedback
A
reduces the effects of the initial change helping maintain dynamic equilibrium. e.g deposition at base of cliff absorbs wave energy reducing erosion
3
Q
dynamic equilibrium
A
a state of balance where inputs = outputs in a system that is constantly changing
4
Q
sources of energy at the coast
A
waves
wind
rip currents
tides
5
Q
wave energy is affected by
A
strength of the wind
duration of the wind
fetch - distance of open water in which wind blows over
6
Q
constructive waves
A
strong swash, weak backwash
low surging waves, long wavelength
beach gain, associated with gentle beach
calm weather, short fetch
7
Q
destructive
A
weak swash, strong backwash
high plunging waves, short wavelength
beach loss, associated with steep beaches
stormy weather
8
Q
wave refraction
A
distortion of wave fronts as they approach the shoreline, causing energy to be concentrated at headlands and dissipated at bays. deep water causes waves to travel faster. shallow water causes drag - this causes a bend in the wave
9
Q
rip currents
A
narrow, fast channels of water that flow from the shore back out to sea.
10
Q
how are wave refraction formed
A
deep water causes waves to travel faster. shallow water causes drag - this causes a bend in the wave
11
Q
how are rip currents formed
A
series of plunging waves causes a temporary build up of water at the shore, water then finds area with least resistance and rushes back out to sea
12
Q
tides
A
the periodic rise and fall of the level of the sea in response to the gravitational pull of the sun and moon
13
Q
neap tides
A
lowest tidal range
moon at right angle to sun
gravitational pull acts against each other
14
Q
spring tides
A
highest tidal range
sun + moon in line
gravitational pull acts together
15
Q
sediment cell
A
stretch of coastline, usually bordered by 2 prominent headlands + movement of sediment is contained
16
Q
inputs
A
rivers, cliff erosion, lsd, wind, glaciers
17
Q
transfers
A
lsd + onshore/offshore processes e.g rip currents
18
Q
stores
A
beaches, sand dunes, offshore deposits
19
Q
sediment budget
A
the balance between inputs and outputs in a system
20
Q
freeze thaw weathering
A
water enters cracks, freezes and expands, breaking away rock
21
Q
wetting + drying
A
rock expands when wet + contracts when dry
22
Q
salt crystallization
A
salt water evaporates leaving salt crystals which exert stresses in rock causing them to break up
23
Q
carbonation
A
rain is slightly acidic + reacts with carbonate rocks e.h limestone
24
Q
oxidation
A
rock reacts with oxygen causing rusting + breakdown effect
25
solution
dissolving of rock minerals
26
mass movement
the downhill movement of material under the influence of gravity.
27
soil creep
extremely slow form of movement of individual soil patrticles downhill.
soil expands at right angles to slope
soil shrinks + falls straight back down
28
mudflow
involves earth + mud flowing downhill due to material becoming saturated
29
landslides
block of rock moving downhill very rapidly remaining intact
30
rockfall
sudden collapses of rock fragments
associated with steep cliff faces and triggered by weathering + earthquakes
31
rotational slumping
weaker rock types that become saturated and heavy
land slips downwards on a curved slip plane
leaves distinct stepped landscape
32
hydraulic action
sheer force of water as it crashes agaisnt rocks
- causes air to be forced into cracks, when wave retreats, crompressed air expands, weakening joints in the rocks
33
wave quarrying
high-energy waves impact a cliff face with such intense force that they dislodge and remove large, loose chunks of rock or smaller weathered fragments.
34
abrasion
rocks carried in waves scape against cliff surface
35
attrition
sediment knock/rub together changing the size of the sediment
36
solution (erosion)
weak acids in the seawater can dissolve alkaline rock
37
traction
pebbles + larger material are rolled along the sea bed
38
Saltation
smaller sediemnt bounced along the seabed
39
suspension
small material held in the flow of seawater
40
solution (transportation)
dissolved material carried in soultion
41
longshore drift (littoral drift)
- influenced by prevailing winds
- waves approach at an angle
- swash carries materiel up beach at 45 degree angle
- backwash carries materiel down beach at 90 degree to coast
- creates zig-zag movement
42
Example of wave cut platform and how it is formed
- Flamborogh head, Holderness
- HA + abrasion attack base of cliff causing a notch to form
- undercutting causes notch to bet bigger creating overhang
- notch migrates inland + cliff retreats
- cliff becomes unstable + collapes
- leaves an exposed wcp
43
example of caves, arches, stacks + stumps and how they're formed
- Old Harrys rocks, Dorset
- waves erode joints + cracks in headland + widen to form a cave
- erosion cuts all the way through headland until arch is formed
- roof eventually collapses due to weathering + lack of support leaving a stack
- overtime, eroded + weathered to form a stump
44
example of headlands and bays and how they're formed
- Durdle door, dorset
- alternating bands of hard (limestone) + soft rock (sandstone) at right angles to the shoreline
- soft rock is eroded quicker
45
swash-aligned beaches
- low energy environments
- waves break parallel to shore, depositing sediment onto the beach
46
drift-aligned beaches
- waves approach beach at an angle, lsd moves sediment along the coast often forming a spit
47
features on a beach
- runnels - series of ridges parallel to coast near low water mark
- berms - series of ridges near high water mark
- cusps - semicirclular shaped depresses with courser material around the edge + finer materiel in the middle
48
example of a spit and how it is formed
- spurn head, holderness
- lsd transports sediemnt along the coastline. when coast changes direction, wave energy decreases + sediment is deposited in same direction, creating long thin ridge
49
compound spit
- compound spits have multiple recurved ends
- recurved ends are formed by occasional changes to wind + wave direction
50
example of bar and how it is fomed
- slapton sands, devon
- spit joins to 2 headlands together, leaving lagoon behind
51
example of tombolo and how it is formed
chesil beach, dorest
- spit joins to an island
52
offshore bars
- submerged or partly exposed ridges of sand
- destructive wavces erode sand from beach with strong backwash + deposit it offshore
53
example of a barrier isalnd and how it is formed
Scolt Head, Norfolk
1. spits have been breached off
2. sediment builds up onto offshore bars
3. former coastal dunes + ridges that were flooded during the ice age from rising sea levels
54
example of sand dunes and how they form
seston coast
- sand is moved inland by saltation and wind
- sand becomes trapped on obstacles, usually pebbles, driftwood, vegetation
- as mound grows it becomes an embryo dune
- pioneer species e.g marram grass colonise + stabalise sand
- yellow duens formed - higher, more vegeataton
- overtime, dunes migrate inland increasing vegeation cover + organic matter - here grey dunes+ dune slacks are found
55
example of muflats/saltmarsh and how they form
keyhaven marshes
- formed in sheltered, low energy environments e.g river esturies or behind spits
-rivers bring sediment downstream + tidal currents bring marine sediments
- flocculation occurs (clay particles stick together) building up layers of mud, creating mudflats
- pioneer halophytes (plants in saline environments) colonise which traps more sediment + mud, rising above high tide line, forming mature saltmarsh
56
how does rock type affect erosion
igneous - formed from cooling of magma e.g granite, basalt
- slow erosion rate
metamorphic - existing rock changed by heat + pressure e.g slate, marble
- slow to medium erosion
sedimentary - compacted sediment e.g sandstone, limestone
- fast erosion
57
how does the presence of a beach effect erosion
beaches absorb wave anergy + reduce impact of erosion on cliffs
58
how do subaerial processes affect erosion
weathering + mass movement - weaken cliffs + create piles of debris that are easily eroded
59
how does cliff profile effect erosion
- horizontal dip - verticle cliff face, steady erosion
- seaward dip - creates overhang, leads to rockfall, high erosion
- landward dip - rock layers tilted back, more stable cliff face, low erosion
- steep seaward dip - sloping profile, jagged, high erosion
60
how do groynes and sea walls effect erosion
- groynes - trap sediment from LSD depriving beaches further down
- sea wall - deflect wave energy elsewhere along the coast
61
how does the geological structure of the coast effect erosion
- cracks, joints, bedding planes, faults create weakness in cliff
- discordant - forms headlands + bays
- concordant - hard rock protects soft rock, when soft rock eroded it can get breached creating coves
62
Eustatic change
a global change in sea level resulting from an actual fall or rise in the level of the sea itself.
63
Isostatic change
local changes in sea level resulting from the land rising or falling relative to the sea
64
Submergent landforms
formed when sea level rises or land sinks - rias, fjords, dalmation coasts
65
Fjords
drowned glacial U shaped valleys formed when glaciers retreat and sea levels rise. e.g Sogne Norway
66
Rias
drowned river valleys fformed by rising sea levels flooding river valleys. e.g Kingsbridge Estury, Devon
67
Dalmation coasts
Formed where valleys and ridges run parallel to the coast and are partially submerged by rising sea levels. e.g croation
68
Emergent landforms
formed when sea level falls or land rises (due to isostatic rebound after ice melting). - raised beaches, marrine terraces
69
Raised beaches
Former beaches now above present sea level e.g isle of arran, scotland (commonly found in scotland). Often have wave cut platforms exposed
70
Marrine Terraces
a series of raised beaches formed at different times as the land slowly rises or sea levels fall creating a sequence of step like platforms. e.g parts of western scotland.
71
Relict cliffs
old cliff lines found inland above the current sea level. e.g western scotland, isel of arran
72
2 procceses driving changes in sea level
increase in volume of ocean
subsidence of the coast
73
2 ways in which volume of ocean is increasing
rising climate causes ice caps to melt into oceans
thermal expansion - ocean water expanding as it warms due to absorbing heat
74
Subsidence of the coast
the gradual sinking of the land caused by natutral procceses like sediment compaction and glacial rebound
75
glacial rebound
glacial load removel in the north west of the uk is causing land to rise, whilst the south east of the uk is gradually sinking
76
Groynes
Timber/rock structures built at a right angle to the coast to trap sediment being moved by lsd.
77
positive + negative of groynes
- increase toursit potential, not too expensive
- starve beaches further down making it more susceptible to erosion
78
Sea walls
stone/concrete walls at foot of cliff or top of beach.
79
positive + negative of sea walls
- effective protection against erosion
- refelct wave energy elsewhere, very expensive to build/maintain
80
rock armour
large rocks forming permeable barrier to sea.
81
positive + negative of rock armour
- relatively cheap + easy to construct
- can be dangerous for people climing on them
82
revetments
sloping wooden/concrete/rock structures at top of beach/ foot of cliff
- intrusive + very unatural loooking
83
positive + negative of revetments
- generally cheaper than sea walls
- intrusive + very unatural loooking
84
offshore breakwater
a partly submerged rock barrier, designed to break up the waves before they reach the coast.
85
positve + negative of offshore breakwater
- effective at reducing the wave energy reaching
- vissualy unappealing
86
Beach nourishment
addition of sand/pebbles to make beach wider
87
positves + negatives of beach nourisment
-looks natural + increase tourism potential
- needs constant maintenance
88
cliff regrading + draiange
reducing angle of the cliff to help stability. draiange removes water to prevent landslides + slumping
89
positives and negatives of cliff regrading + drainage
- effective at protecting homes from landslides + slumping
- often causes cliff to retreat + drained cliffs can dry out leading to rock fall
90
dune stabalisation
marram grass planted to stabalise dunes
91
positve + negative of dune stablisation
- maintains natural coastal environment + provides habitats
- time consuming
92
marsh creation
allow low lying areas to become flooded by sea forming a salt marsh
93
positves + negative of marsh creation
- creates natural buffer to powerful waves + natural habitat
- agricultural land is lost
94
Shoreline management plans (SMPs)
a long-term strategic document (usually covering 100 years) that sets out how to manage flood and erosion risks for specific stretches of coastline
95
hold the line
using hard engineering to maintain current postion of coastline
96
advance the line
extending the coastline out to sea (by encouraging build up of a wider beach, using beach nourishment and groynes.
97
managed retreat
allowing the coastline to retreat in a managed way e.g creating salt marshes
98
do nothing
letting nature take its course and allowing the sea to erode cliffw and flood low lying land
99
Integrated coastal zone management (ICZM)
holistic (considers the entire coastal system), long-term approach to managing coasts that aims to balance environmental, social and economic goals. focus on sustainable development, considers future risks, involves stakeholdrs like local businesses, governments, and NGOS.
Physical Geography
flashcards
Decks in class (16)
# Cards
-
water + carbon119
-
Amazon rainforest29
-
The River Exe20
-
coasts99
-
The Holderness Coastline13
-
Odisha16
-
Hazards88
-
hazards (Iceland)9
-
hazards (Montserrat)9
-
hazards (tohuku)8
-
hazards (haiti)9
-
hazards (hurricane harvey)10
-
typhoon haiyan11
-
hazards (black summer)7
-
Phillipines (MHE)13
-
Storm Desmond11
