Physical Geography

Question 1

What is a system?

Answer 1

A system is a set of interrelated components working together towards some kind of process

Question 2

How is the coastline a system?

Answer 2

The coastline is an open system. It has a range of inputs, components, stores, flows, transfers and outputs that combine to form distinctive landscapes

Question 3

What is a dynamic equilibrium?

Answer 3

When there is a balance between the inputs and outputs then the system is in a state of dynamic equilibrium. If one of the elements of the system changes, then the beach features may change and the equilibrium is upset, the dynamic equilibrium is upset by extreme events such as storms, humans can also cause disruption to it for example by removing beach material

Question 4

What is positive feedback?

Answer 4

Where the effects of an action are amplified or multiplied by subsequent knock -on effects (normally done by people)

Question 5

What is negative feedback?

Answer 5

Where the effects of an action are nullified by its subsequent knock-on effects (normally through natural processes)

Question 6

Output

Answer 6

Material or energy moving in from the system to the outside e.g. ocean currents, rip tides, sediment transfer, evaporation

Question 6

Input

Answer 6

Material or energy moving in to the system from the outside e.g. precipitation or wind

Question 7

Energy

Answer 7

Power or driving force e.g. energy associated with flowing water, the effects of gravity on cliffs and moving air

Question 8

Stores/components

Answer 8

The individual elements or parts of a system e.g. beach, sand dunes, nearshore sediment

Question 9

Flows/transfers

Answer 9

The links or relations between the components e.g. wind-blown sand, mass movement processes, LSD

Question 10

Positive feedback examples

Answer 10

Coastal management can inadvertently lead to an increase in erosion elsewhere along the coast. Groynes trap sediment, depriving ares further down of beach replenishment, this can increase erosion. Sea walls have the same effect by transferring high energy waves elsewhere along the coast

Question 11

Negative feedback examples

Answer 11

When the rate of weathering and mass movement exceeds the rate of cliff-foot erosion a screw is formed. Over time, this material extends up the cliff face protecting the cliff face from subaerial processes. This leads to a reduction in the effectiveness of weathering and mass movement

Question 12

Dynamic equilibrium

Answer 12

A state of balance within a constantly changing system e.g. constructive waves build up a breach, asking it steeper, this encourages the formation of destructive waves that plunge rather than surge. Redistribution of sediment offshore by destructive waves reduces the beach gradient. This encourages waves to become more constructive

Question 13

Backshore

Answer 13

Area between the high water mark and landward limit of marine activity. Changes take place during storm activity

Question 14

Foreshore

Answer 14

Area between the high water mark and the low water mark. Most important zone for marine processes that are not influenced by storm activity

Question 15

Inshore

Answer 15

Area between the low water mark and the point where waves cease to have any influence on the land beneath them

Question 16

Offshore

Answer 16

Area beyond the point where waves cease to impact upon the seabed. Activity is limited to deposition of sediments

Question 17

Wind

Answer 17

Wind is a vital input into the coastal system as it is the primary source of energy for other processes. It is also and important agent of erosion and transportation

Question 18

4 Features of wind as an input into the coastal system

Answer 18

Prevailing wind
Fetch
Formation of waves
Agent of erosion

Question 19

Prevailing wind

Answer 19

Most coastlines have a direction that the wind comes from most often. This influences the amount of wave energy. Our prevailing wind is from the South

Question 20

Fetch

Answer 20

This is the distance of open water over which a wind blows interrupted. The length of fetch determines the magnitude of energy of the waves

Question 21

Formation of waves

Answer 21

Waves are created by the transfer of energy from the wind blowing over the sea surface. The energy acquired by the waves depends on the stretch of the wind

Question 22

Agent of erosion

Answer 22

Wind can pick up and move sediment from the coast, and also use it to erode other features

Question 23

Waves

Answer 23

Once created and driven by the wind, they are the primary agent of shaping the coast

Question 24

Characteristics of constructive waves

Answer 24

Wave height- low, under 1 metre
Wavelength- long
Frequency- 8-10 waves per minute
Smash- strong smash
Backwash- weak backwash
Beach profile- gentle/flat

Question 25

Characteristics of destructive waves

Answer 25

Wave height- over 1 metre
Wavelength- short
Frequency- 10-14 waves per minute
Swash- weak swash
Backwash- very strong backwash
Beach profile- Steep

Question 26

Wave refraction

Answer 26

The shape of the —
coastline can cause waves to bend and change direction
- As each wave approaches the coast, it drags in the shallow water at the headland. This increases the wave height and shortens the wavelength and results in increased erosion at the headland. Lower energy waves spill into the bays either side, resulting in increased deposition

Question 27

What is a current?

Answer 27

The term current refers to the permanent of seasonal movement of surface water in the seas and oceans

Question 28

There are three main types of current:

Answer 28

Longshore currents (littoral drift) – most waves do not approach the headline ‘head on’, but rather at an angle to the shoreline. This generates a current running parallel to the shoreline.
Rip currents- these are strong currents moving away from the shoreline.
They develop when seawater is piled up along the coastline by incoming waves. The current may run parallel to the coast before flowing out through the breaker zone.
Upwelling – this is the movement of cold water from deep oceans towards the surface. The denser cold water replaces the warmer surface water and creates nutrient rich cold Ocean currents.

Question 29

Tides:

Answer 29

The Sun and moon both have an influence on the tides, but the moons influence is stronger, as it is closer
The moon pulls water towards it, creating a high tide in that part of the world, and there’s a compensatory high tide on the opposite side of the world. In the areas between this, the tides is at its lowest
There is a high tide every 12.25 hours on average
The tidal range is the vertical distance between high tide and low tide. Low tile range tends to produce a narrower beach, which is prone to higher rates of erosion

Question 29

Two types of tides:

Answer 29

Spring tides – as the moon orbits the Earth the high tide follow it. Twice in a lunar month, when the moon, sun and earth are in a straight line, the tidal force is amplified. This produces the highest monthly tides (spring tides)
Neap tides – also twice a month, the moon and the Sun are positioned at right angles to one another in relation to the Earth. This alignment gives the lowest monthly tidal range (neap tides)

Question 29

Characteristics of high energy coasts

Answer 29

Energy level – high energy waves
Deposition vs erosion – the rate of erosion is greater than the rate of deposition
Landforms – headlands, cliffs, wave cut platforms
Examples – Atlantic coast of northern Europe and Northern America
North Cornish coast in Southwest England

Question 30

What are tidal surges?

Answer 30

Also known as storm surges
They are occasions when meteorological conditions give rise to strong winds which can produce much higher water levels than those at high tide
The east coast of Britain and the north Sea are affected by this
Depressions (intense low pressure weather systems) over the north sea produce low pressure conditions that have the effect of raising sea levels
Sea levels can rise by 1 cm for every 1 millibar drop in pressure
Strong winds drive waves ahead of the storm, pushing the sea water towards the coastline
This has the effect of piling up water against the coast
The shape of the north Sea means that often water is increasingly concentrated into a space that is decreasing in size (tunnelling)
High tides, especially those of spring tide, intensify the effect
The north Sea was affected by a title surge in 1953
Storms and surges of December 2013 and January 2014 brought some places along the east coast of England higher water levels than 60 years earlier

Question 30

Characteristics of low energy coasts

Answer 30

Energy level – low energy waves
Deposition vs erosion – rate of deposition often exceeds the rate of erosion of sediment
Landforms – beaches, spits, estuaries, inlets, sheltered bays, Examples – Baltic Sea is an example (has sheltered waters and low tidal rage)

Question 31

Sediment sources

Answer 31

Sediments comes from a variety of sources, including:
Streams or rivers flowing into the sea
Estuaries
Cliff erosion
Offshore sand banks
Material from biological origin (shells or coral fragments)

Question 32

What are sediment cells?

Answer 32

A sediment cell is a length of coastline and it’s associated near shore area within which the movement of coarse sediment (Sand and shingle) is largely self-contained.
Interruptions to the movement of sand and shingle within one cell should not affect beaches in a neighbouring sediment cell
The English and Welsh coastlines are divided into 11 cells which are then divided into sub-cells or management units
Sediment cell theory is a key component of shoreline management plans (SMP) which determine future strategies
Sediment cells are distinct areas of coastline separated from other areas by well-defined boundaries such as headlands and stretches of deep water
Sediment cells can be regarded as closed systems (from which nothing is gained or lost)

Question 33

Sediment cell characteristics

Answer 33

They are discreet and function separately from each other
Within the cell sediment is sourced transferred and stored. Coarse sediments are not exchanged between cells, but finer sediment in suspension can be
Overtime, sub-sinks (temporary stores) will erode, and the sediment will re-enter the cell system
The sentiment in the sink is away from wave action and longshore drift. It becomes essentially an output as it is no longer being worked by the processes within the cell.

Question 34

What is a sediment budget?

Answer 34

The amount of sediment available to the sediment cell
The sediment cell will produce depositional features which are in equilibrium with the amount of sediments available. If the budget is decreased, then the waves will continue to move sediment, causing erosion in some areas. if the budget increases, then deposition is more likely

Question 34

Examples of inputs, transfers and stores

Answer 34

Inputs (sources of sediment) – fluvial sediment, cliff erosion, erosion of wave cut platforms, eroding depositional features e.g. beaches, dunes
Transfers (transportation) – longshore drift, current, saltation
Stores (sinks) – sinks/permanent storage = estuary, offshore bar, dredging (removal of sediment), submarine canyon
Sub-sinks /temporary stores = sedimentary features e.g. Beaches, dunes, spits, bars

Question 35

What is longshore drift?

Answer 35

The movement of material caused by the approach of swash at an angle to the shore and the subsequent perpendicular backwash down the steepest beach gradient which moves the material laterally downdrift. Aided by wave refraction

Question 36

Geomorphological processes

Answer 36

There are two types:
Marine – processes that operate on the coastline that are connected with the sea, such as tides, longshore drift and waves e.g. Transport by waves, deposition by waves, processes of marine erosion
Sub aerial – these operate on land but also affect the shape of the coastline such as mass movement, weathering and run-off. These processes break down the coastline, weaken underlying rocks and allow sudden movements or erosion to happen more easily. Material is broken down IN SITU meaning it remains in its original position e.g. all types of weathering and mass movement, deposition by wind and transport by wind

Question 37

Processes of marine erosion

Answer 37

Attrition – rocks in the water crash into each other, becoming smaller rounder
Abrasion – material in the water thrown against cliff faces and wears them away
Solution – dissolving of rocks in water such as calcium and based rocks like limestone
Wave quarrying – force of air getting into cracks in rock, creating pressure and forcing rocks apart
Hydraulic action – force of water getting into cracks in rock, creating pressure and forcing rocks apart

Question 38

Factors affecting erosion at the coast

Answer 38

Wave steepness – steeper waves are high energy waves and have greater erosive power than low energy waves
Breaking point – waves that break at the foot of the cliff release more energy than those that break some distance from the shore
Fetch- (the distance travelled by wind or waves across open water) a wave that has travelled further have more energy than one that has not travelled as far
Sea depth- a steeply shelving seabed at the coast will create higher and steeper waves
Beach presence- beaches absorb wave energy and can therefore provide protection against marine erosion
Human activity – if protective material such as sand and shingle are removed from beaches it may lead to more erosion. Construction of groynes will reduce erosion where they are built but may increase erosion somewhere else along the same coastline
Geology

Question 39

Geology is a very important factor in rates of erosion at the coast:

Answer 39

Lithology: refers to the characteristics of rocks, such as resistance to erosion and permeability e.g. very resistant rocks such as granite tend to be eroded less than weaker rocks such as clay. The variation in rates at which rocks wear away is known as DIFFERENTIAL EROSION
Structure: the structure and layout of rocks can affect erosion. Rocks that live parallel to the coast (concordant) creates very different types of coastline then those right angles (discordant)

Question 40

Discordant coastlines

Answer 40

Rocks run at right angles to the coast, allowing the sea to erode weaker clays and sandstones to create large bays e.g. Swanage Bay in Dorset
The harder rock either side is eroded more slowly and creates headlands e.g. Peveril point in Dorset

Question 41

Concordant coastlines

Answer 41

Rocks run parallel to the coast. If the rock closest to the sea is made of limestone e.g.
Portland limestone in Dorset, then Cliffs form as they are more resistant. In a few places, the sea is able to erode through the limestone and a road the week of rock behind it e.g. Lulworth cove

Question 42

Examples of hard and soft rock

Answer 42

Hard rock – chalk, Purbeck limestone, Portland limestone, granite
Soft rock – Kimmeridge clay, Bagshot beds, Wealdon clays and green Sands

Question 43

What is a dip?

Answer 43

The steepest cliffs form in rocks that have horizontal strata (lines) or which dip gently inland. Rocks that dip towards the coast tend to produce much more gently sloping features.

Question 44

Strata

Answer 44

The direction of the layers of the geology

Question 44

Situations where (marine) deposition of cars

Answer 44

When sand and shingle accumulate faster than they are removed
As water slows following breaking
As water pauses at the top of the swash before the backwash begins
When water percolates (travels through the ground) into the beach material As backwash takes it back down the beach

Question 45

What is aeolian deposition?

Answer 45

Aeolian processes refer to transport and deposition of sediment BY WIND
Wind plays an important role in shaping many coastlines
At the coast, when there is a large tidal range, large amounts of sand may be exposed at low tide providing a supply of sediment to be picked up by the wind
Sand is transported by the wind in two ways (dependent on how dry or moist the source of sand is)
Soil creep- a process like traction, where wind rolls or slides sand grains along the surface
Saltation – Where the wind is strong enough to temporarily lift the grains up to 1 meter

Question 46

Sub-aerial processes: weathering

Answer 46

Sub-aerial weathering includes processes that slowly breakdown the coastline, weaken the underlying rocks and allow sudden movements or erosion to happen more easily
Material is broken down in situ, remaining in its original place, it is then moved by mass movement
Sub- aerial weathering at the coast can be categorised as:
Mechanical/physical weathering
Biological weathering
Chemical weathering

Question 46

Sub aerial processes: mass movement

Answer 46

Mass movements are generally either rapid sudden failures of the slope or the effects of processes that develop over some time. No mass movement is possible without the influence of gravity
Types of mass movement:
Rock fall
Landslide
Soil creep
Mud slide
Slumping
Run-off

Question 47

Depositional landforms : beaches

Answer 47

Ripples- features formed as the tide goes out, only visible in low tide, waves retreat creating ripples
Runnels – a dip filled with water (between ridges/berms)
Ridges – when the tide goes in or out, the waves will deposit the sediment when the gradient changes, creating ridges, the beach is not flat
Cusps- naturally formed semi- circular patterns, when wave refraction occurs on a headland, the wave energy is spread out into the bay, therefore the swash divides creating a stronger backwash creating cusps
Offshore bars- typically happen during winter due to disruptive storms/waves. The beaches are eroded, transported and deposited offshore, can’t see offshore bars as they are below the low tide mark
Berms- like a ridge that is further inland, nearer the backshore (inland), it’s only affected during storms or high tide

Question 48

Swash vs drift aligned beaches

Answer 48

The angle at which waves generally approach a coastline will determine the nature of the kind of beach features that develop
Swash aligned beaches:
e.g. Hell’s Mouth
They are produced where the waves break in line (parallel) with the coast. Swash aligned beaches are smoothly curved, concave beaches
The Beach face is orientated parallel to the front of the dominant waves
Beaches which face the waves are termed SWASH ALINGED
Drift aligned beaches:
They are produced where waves break at an angle to the coast
The swash therefore occurs as an angle, but the backwash runs perpendicular to the beach
As a result, material is transported along the beach via longshore drift

Question 49

What does pioneer mean?

Answer 49

The first species
e.g. marram grass are the first species of vegetation to colonise sand dunes

Question 49

Several key conditions are necessary for sand dunes to form:

Answer 49

Sand dunes e.g. Studland Bay Dorset need:
A supply of sand- this can be brought onshore by the waves and positive on large sandy beaches or spits
A large inter-tidal beach area- where sand can be dried out at low tide
Strong onshore prevailing winds- to pick up the dry sand and blow it inland
Obstacles- such as plants, driftwood, or rocks to trap the sand
A large, flat, low lying area- of land behind the beach where the dunes evolve over time

Question 50

What is a psammosere?

Answer 50

The vegetation succession and development of the sand dune

Question 51

What is a bar?

Answer 51

A long stretch of sand stretches across a bay leaving a lagoon behind, if a spit develops across a bay where there is no strong flow of water from the landward side, it’s possible for the sediment to reach across to the other side, forming a bar e.g. Slapton Ley in Devon

Question 52

Simple vs Compound spits

Answer 52

Simple spits- straight or recurved
Do not have minor spits, or recurved edges
Compound spits- may have similar features to simple spits
Have several recurved ridges (ends) or minor spits, possibly marking where they terminated in the past

Question 53

How are spits formed?

Answer 53

Prevailing wins and maximum fetch are from the south-west, so material is carried west to east by longshore drift
The change in coastline to a north-south angle causes a buildup of sand and shingle in the more sheltered water in the lee of the headland
Find a material is carried Eastwards into the deeper water of the estuary and is deposited as the water loses its capacity to transport it
The end of the spit begins to curve round as wave refraction carried material round into the more sheltered area, the fetch may also contribute to this. Behind the spit is now sheltered which encourages more deposition of sediment, and a salt marsh can form over time

Question 54

What is a tombolo?

Answer 54

A long stretch of sand joining an island to the mainland, a spit that joins an island to the mainland is Tombolo e.g. Chesil beach on the South Coast of the UK, which joins the Isle of Portland to the mainland

Question 55

What is brackish water?

Answer 55

Water found in salt marshes
Salt and freshwater