coasts

Question 1

What is the littoral zone

Answer 1

An area of land close to the shore that extends to the continental shelf. It consists of backshore, nearshore, foreshore and offshore zones

Question 2

what factors form a rocky coast?

Answer 2

Where resitent rock geology can withstand rapid erosion from high energy coasts.

Question 3

Explain the coast line of cornwall

Answer 3

Cornwall bears the brunt of the highest energy waves in the UK, due to it’s position in the south west, the waves that hit the coast line have an extremely large fetch of the whole Atlantic. It is not rapidly eroded however, as much of cornwall is made up of resistent rocks:
* igneous rocks, such as basalt and granite
* compressed sedimentary rocks, like red sandstone
* metamorphic rocks, like shicst

Question 4

Explain the formation of coastal plane landscapes

Answer 4

areas of low relief and result from supply of sediment from different terrestrial and offshore sources, often in a low-energy environment.

Question 5

What is a concordant coast?
What is an example of a landform in a concordant coast?

Answer 5

Where bands of more and less individual rock run parralel to the coast. This creates a coast which has similar shapes and features across it’s length.
The south of the Isle of Purbeck is a concordant coast. Here, when the more resistent band of rock is eroded, the less resistent layer which is now exposed is eroded at a much greater rate, creating Lulworth cove (bay/cove)

Question 6

What is a discordant coast? What is an example?

Answer 6

A discordant coast occures where bands of more and less resistent rock lay perpindicular to the coast. For example, the East of the Isle of Purbeck

Question 7

What landforms are created in the East of the Isle of Purbeck as a result of the discordant coast?

Answer 7

The less resistent bands of unconsolidated clays are eroded, forming a large bay.
The more resitent bands of chalks withstand theerosion and are left ‘sticking out’, forming a headland.

Question 8

What are dalmation coasts?
What are Haff coasts?

Answer 8

• Dalmation coasts - a type of concordant coastline where valleys and ridges ran parallel to each other. When sea levels rose, the valleys flooded, leaving the peaks of the ridges as floating islands. It iis named after the dalmation coasts in Croatia
• Haff coasts - concordant coastline where long spits of sand and lagoons are alligned parallel to the coast.

Question 9

explain how Geological structure (bedding planes, jointing, dip, faulting, folding) is an important influence on coastal morphology and erosion rates.

Answer 9

Bedding Planes: These are the layers of rock that form during deposition. The orientation and spacing of bedding planes affect how resistant the rock is to erosion. If the bedding planes are horizontal, the rock may resist erosion more uniformly. However, if the bedding planes are inclined or tilted, the coast may experience differential erosion, where some layers are eroded faster than others, leading to uneven coastal features like cliffs and terraces.

Jointing: Joints are fractures in rock where no displacement has occurred. These natural weaknesses in the rock structure make it more susceptible to erosion. Coastal areas with extensive jointing can develop features like sea stacks, arches, and blowholes as waves exploit these fractures over time. The spacing and orientation of joints affect the rate and pattern of erosion.

Dip: The dip refers to the angle at which rock layers are inclined. A steeper dip may lead to faster erosion of the rock face, especially along coastlines. If the dip is towards the coast, it may cause more rapid erosion, as waves attack the more vulnerable, sloping surface. Conversely, if the dip is away from the coastline, the rocks may be less exposed to direct wave action, potentially leading to slower erosion.

Faulting: Faults are fractures where movement has occurred, often resulting in vertical displacement. Coastal areas with active faulting may exhibit significant features such as fault scarps or vertical cliffs. Fault lines can also influence the pattern of erosion, as areas near fault zones may be more prone to collapse or subsidence, affecting coastal landforms.

Folding: Folding occurs when rock layers are bent due to tectonic forces. The orientation and scale of folds can influence the coastline’s appearance. For instance, coastal areas with large-scale folds may experience complex landforms like ridges, valleys, or cliffs that can either resist or accelerate erosion, depending on the fold’s orientation relative to wave action.

Question 10

how does rock type - igneous, sedimentary, metamorphic and
unconsolidated material affect rates of coastal recession.

Answer 10

• igneous rocks, such as granite, are cyrstaline and impermeable, making them more resistent
• sedimentary rocks are porous and permeable, meaning water and air can enter the rocks, making them more succebtable to erosion
• metamorphic rocks like schist are extremely resistent to erosion
• unconcolidated material like boulder clay are loose and not cemented together, meaning they are easily eroded

Question 11

How does vegitation stablise material?

Answer 11

• stems and leaves protect sediment from marine erosion at high tide
• it prevents wind erosion and low tide
• they decrease velovity of the water and waves
• When plants die, they add humus (organic matter) to the soil

Question 12

Explain the formation of a sand dune

Answer 12

1. Embryo dunes - when driftwood or other materials form a shelter and trap sand. Pioneer plants such as sea couch colonise the sand and stabalise it, which allows marram grass to grow - it has roots 3 meters long which futher stabalises the sand
2. as the dune continues to grow, the surface becomes yellow as more sand is built up
3. futher along the sand dune, plants will begin to die, adding humus to the sand creating soil, which less halophytic (salt adapted) plants to grow, such as gorse heather - grey dunes
4. Fixed dunes are formed well above sea level
5. Climax - the soil is now moisture and nutrient rich, allowing non-xerophytic plants to grow, eventually forming a woodland.

Question 13

Explain the formation of salt marshes

Answer 13

• Salt marshes a formed in estuarys - where the mouth of a river meets the sea
• Here, fresh and salt water mix - this causes suspended salt particles to clump together due to flocculattiion and eventually sink
• blue-green algae colonise the deposited clay
• this process is repeated overtime , reducing water depth and exposing the clay for longer. halophytic plants such as cord grass colonise.

Question 14

What are destructive waves and how do they influence beach morphology?

Answer 14

Destructive waves are high plunging waves, which have a stronger backwash than swash, with a circular orbit. They have a shortwavelength, so occure more frequently (11-16 wpm). Beaches are eroded as the strong backwash carries material away to offshore barns. The strong verticle plunging, which crashes down at about 120 degrees, creates a step in the beach

Question 15

What are constructive waves? How do they influence beach morphology?

Answer 15

Constructive waves are low, surging waves with a long wavelength (so less frequent, occuring at 6-9 wpm). The waves orbits are more eliptical. Material is carried up the beach, and the point at which the waves stops a berm is created. As the backwash is so weak, it can not carry large matierial as far down the beach, so beach material ends up being sorted by size

Question 16

What are the four erosional processes.

Answer 16

Hyrdaulic action- physical impact of waves against a cliff face, where water enters cracks and compresses air inside them. This sudden change in pressure (when the wave recedes) can cause the rock to weaken and break apart.
abrasion - when material transported by waves gets hurled at the base of the cliff
attrition - when tansported material collides with each other, gradually wearing it down
Corrosion - when the slightly acid sea water reacts with calciumm bicarbonate in alkali rocks, causing a chemical reaction

Question 17

What is a wavecut platform?

Answer 17

A flat area found at the base of the cliff as a result of erosion

Question 18

What is a wave cut notch?

Answer 18

A curved indentation at the base of a cliff, caused by erosional processes such as hyrdaulic action. As these get bigger, the cliff will collapse under its own weight and retreat, leaving behind wave cut platforms.

Question 19

Explain the cave - arch - stack - slump sequence

Answer 19

A crack is opened through erosional processes, and continues to grow (positive feedback loop as more rock is exposed to the sea). This continues until the cave reaches the other end of the headland, forming an arch. This arch will eventully collapse under its own weight, leaving a stack which gets eroded down to a stump

Question 20

What is longshore drift?

Answer 20

Waves approach the beach at the angle of the prevailing wind. The backwash then retreats perpindicular to the sea, under gravity. the net affect is the latteral shift of sediment in the direction of the prevailing wind, known as long shore drift.

Question 21

How are beaches formed

Answer 21

beaches are accumalations of sand, shingle and other fine sediment found in the foreshore and backshore litoral zones. They are formed through the depositioin of material by constructive waves

Question 22

What are spits and how are they formed?

Answer 22

Spits are linera ridges of sand that protrude out of the coastline into the sea. they occurre when long shore drift continues to carry material into the sea when the coastline changes direction. The spit needs a constant supply of material or it will be washed away. A spit may become recurved due to a change in the direction of privailing wind, strong inwards currents or wave refaction.

Question 23

What are double spits?

Answer 23

When longshore drift is happening in opposite directions at either end of a bay, possibly due to wave refraction. This has occured at Poole Habour, Dorset

Question 24

what are offshore bars?

Answer 24

Offshore bars are ridges of sand or shingle running parallel to the coast in an offshore zone.
They form from sediment eroded by destructive waves and carried seawards by backwash.
The sediment is deposited at the boundary of the offshore and nearshore zone, where the orbit of water particles ceases to reach the seabed, halting the transport offshore.

Question 25

What is a barrier beach/ bar? where can one be found

Answer 25

A linear ridge of sand that extends across the entire width of a bay. This occures when a spit forms and meets between two headlands. There's a 9 km barrier beach across Start Bay in Devon, forming Slapton Ley lagoon behind it

Question 26

What is a tombolo?

Answer 26

A sand or shingle ishtmus, connecting a coast with an offshore island. They are usually formed on a drift alligned coastline, where longshore drift creates a spit protruding out of the coastline and connects to the island. They can also be formed on a swash alligned coastline, where wave refraction carries waves round the islands and cancels each other out where they meet, creating an area of calm where deposition can occure.

Question 27

What is a cuspate foreland?

Answer 27

Where longshore drift occures in opposite directions at the border of two sediment cells, two spits are formed and merge together to form a triangular protrusion of sediment

Question 28

What is a sediment cell? What is an example?

Answer 28

A sediment cell is a distinct stretch of coastline in which the inputs, outputs and movement of sediment within it is largely a system. The amount of sediment available within each cell is known as the sediment budget. There are 11 sediment cells in the uk, 2a is the holderness coast

Question 29

What is an example of positive and negative feedback in a sediment cell?

Answer 29

Negative feedback: when the change produced creates effects that operate to reduce or work against the original change. E.g. when erosion leads to blockfall mass movement. The collapsed debris acts as a barrier protecting the cliff base, slowing or preventing erosion for a period of time. Positive feedback: when the changed produces an effect that operates to increase the original change. E.g. When wind erosion of a dune section during high velocity storms may removing stabilising vegetation. Further wind erosion now occurs in later low velocity wind conditions, increasing the depletion of dune sand.

Question 30

What is the difference between erosion and weathering?

Answer 30

erosion involves the movement of the broken down material, whereas weathering happens in sittu.

Question 31

What are the three forms of mechanical weathering?

Answer 31

* freeze-thaw weathering - when water enters the cracks in rocks and freezes, it expands by 9%, causing the rocks to fracture even more * salt crystalisation - when salt water evaporates, it leaves behind salt crystals, which can grow and exert pressure onto the rocks * wetting and drying - rocks rich in clay such as shale exoand when they are wet and contract when they are dry, when repeated over time this weakens the rcks and causes cracks to form

Question 32

What are the two types of chemical weathering?

Answer 32

* oxidation - oxidation occures when iron rich rocks such as liimonite begin to rust - this weakens and destabises the rocks * Carbonation - rainwater absorbs co2 from the air, which forms a weak carbonic acid. This reacts with calcium carbonate in alkali rocks like chalk to form calcium bicarbonate, which is easily desolved and eroded. This occures more in winter, as rainwater can absorb more co2 in colder temperatures

Question 32

What are two examples of biologial weathering

Answer 32

plants may grow in the cracks in the rocks, meaning the expansion of their roots exerts pressure Boring Molluscs - drill into the rocks at coasts to protect themselves, they do this by producing a weak acid

Question 33

What are the three types of flow mass movements?

Answer 33

* soil creep - the slowest form of masss movement, the downhill movement of individual soil particles * solifluction - occures in Tundra areas, where the top layer of soil melts, but underneath remains frozen. this top layer becomes saturated and flows over the frozen layer * mudflows - an increase in the amount of water for example due to heavy rain, reduces friction and causes materials to flow over each otherr

Question 34

How much has sea level risen since 1880? How much has sea level risen a year since 2006?

Answer 34

8-9 inches 3.6mm, which is 2.5 times the average of the 20th century

Question 35

What are the two forms of sea level change?

Answer 35

Eustatic - sea leel rise on a global scale, caused by a change in the volume of water in the ocean store. Isostatic - local sea level change caused by a change in land level relative to the ocean

Question 36

What has caused eusatic sea level rise?

Answer 36

An icrease in global temperatures has two main effects on sea level. One, it redduces the amount of water stored in the cryosphere, in glaciers and ice sheets. If the ice in greenland and antartica were to melt, sea levels would rise by 66m. A second reason is thermal expansion - water when it is warmer, the molecules vibrate more, as well as the intermolecular forces weakening. This means tthe water takes up more space. About 50% of modern sea level rise has been casued by this.

Question 37

What causes isostatic change in sea level?

Answer 37

Duriing the last ice age, much of the uk was covered in glaciers, sometimes up to 3km thick. The immense weight of this ice caused the land to subside into the mantle. As the ice melted, the land is now slowly readjustying and tilting upwards, known as post glacial rebound. Scotland is rising by 1-2mm a eyar, while cornwall is falling by 0.5-1.5mm a year

Question 38

What do tectonics have to do with sea level rise?

Answer 38

Tectonics can shift sea beds upwards - Indian ocean earthquake 2004 increased sea levels by 0.1mm

Question 39

What landforms are created by sea level falling (land forms of emergance?)

Answer 39

Raised beaches with fossil cliffs - beaches and cllffs that have been left inland due to the retreat of sea level, e.g in the isle of arran

Question 40

What landforms are caused by a rise in sea level? (landforms of submergance)

Answer 40

* Rias - where a rise in sea level has permantely drowned a floodplane around the river, whilst leaving the highest land untouched. Eg kingsbridge estury, Deven * Fjords - flooded glacial valley - Norway nearly has 1200 * Dalmation coast - where glacial valleys run parallel to the coast, so when sea leveels rise they flood the valley, leaving the peaks of the mounts visible leaving a series of islands

Question 41

explain the risk of flooding for Kiribati

Answer 41

kiribati is a country in the Pacific ocean is coprised of 33 islands. The islands are extremely vulnerable to flooding, and by 2100, an estimated 40cm rise in sea level risks the islands disappearing. Increasing salt water encrouchment ccontaminates ground water supplies and kills crops. 5 citizens applied to refuge in the New Zealand but got rejected. In places, the sea level is rising by 1.2cm a year - 4X the global average.

Question 42

what makes Bangladesh at risk of floods? What human factors have exacerbated flood risk?

Answer 42

* Bangladesh has a population of 175 million in 2024 * 50 million live less than 5m above sea level * subsidence - some of bangladesh's esturine islands have sunkk 1.5m over the last 50 years, due to the implementation of embankments which have prevented deposition from occuring, and thus the natural repleneshment of the islands height * removal of vegitation - Half of all mangrove forrests have been lost since the mid 20th century, deforesatition to make way for shrimp farms accounts for 25% of this loss. Mangroves act as a barrier to coastal erosion, aswell as to extreme events such as tsusnami and storm surges, as they absorb and disperse tidal energy.

Question 43

Whats an example of a country protecting it's mangrove forests?

Answer 43

Sri Lanka - government has protected all of it's mangroves

Question 44

What is a storm surge?

Answer 44

Storm surges are changes in sea level caused by intense low pressure systems. Every drop of 1Mb in air pressure causes sea level to rise by 1cm

Question 45

What were the impacts of Cyclone Sidr?

Answer 45

* November 2007 * storm surge of up to 6m * 4234 people died * $1.7 billion in damages * Embankments failed in many villages, allowing for flooding to enter * Salt water encroachment in villages killed rice crops as well as the drowning of many cattle - destroyed livelihoods socially and economically

Question 46

What were the impacts of the december 2013 storm surge?

Answer 46

* In the uk * 2 people died * 1400 homes flooded * £100 million in damages * In the netherlands, flood defense systems built after the 1953 surge prevented any cacualties.

Question 47

Where is the Holderness coast?

Answer 47

In North East England, in the East Riding of Yorkshire.

Question 48

How quickly is the Holderness coast eroding?

Answer 48

around 2m a year, making it the fastest eroding coastline in Europe.

Question 49

Why is the Holderness Coast's geology a problem?

Answer 49

Geology - Boulder clay is structually weak due to it being unconsolidated. Boulder clay is vulnerable to wetting-drying (the expansion and contraction of clay causes it to crack and weaken over time). Water then can percolate into these cracks, causing the cliff to become lubricated and much heavier, and then slumping under it's own weight. Futher more, the chalk cliffs at flamborough head are suceptable to carbonisation.

Question 50

What other factors contribute to erosion at Holderness

Answer 50

* Wave energy - currents circulate around the uk from the Atlantic to the north sea, adding to the wave energy. The sea floor is deep at holderness, so waves do not get slowed down by friction along the sea floor. * The north sea experiences frequent storms and storm surges (December 2013) * Longshore drift of boulder clay is ineffective as the particles become so fine they get transported out to sea rather then being deposited along the beach. In addition, the Groynes built in Hornsea starved Mappleton of sediment (terminal groyne syndroe), causing erosional rates of up to 4m a year.

Question 51

What are the 5 forms of hard engineering?

Answer 51

* Sea walls - vertical walls (usually slightly curved to reflect energy back at the sea) built at the top of a beach or the base of a cliff to protect against erosion * Groynes - wooden or rock structures built at right angles to the beach to trap sediment, effectively preventing Longshore drift * Revetments - sloping wooden or concrete structures built against a cliff to absorb wave energy * Rip-Rap - Large rocks placed along a beach to break up waves and dissipate their energy. * Offshore breakwater - A partly submerged rock barrier built in the offshore zone to break waves before they reach the coast

Question 52

Where are groynes used in Holderness? What are the pros and cons

Answer 52

Groynes are found in Hornsea * Build up of beach can protect the beach, thus encouraging tourism and promote natural ecosystems, it can also protect sea walls from basal scour * Groynes starve beaches further along the coach of sediment as it interrupts long shore drift. This is known as terminal groyne sydrome. Hornsea groynes have starved mappleton of sediment (erosional rates of 4m a year there)

Question 53

Where are sea walls used in Holderness? What are the pros and cons?

Answer 53

Withernsea in Holderness, following a cost benefit analysis, replaced a straight sea wall with a curved one in 1990 for £6.3 million. * They provide the highest level of protection for residential and commercial areas, protecting the local economy. They also create a prominade. * However, they are extremely exoensive, and interfere with natural processes such as sand dune succession and the balance in the sediment cell.

Question 54

Where are offshore breakwaters used? What are their advantages and disadvantages?

Answer 54

Newhaven in Essex * Relatively cheap form of hard engineering,sometimes as low as £1000 per meter * reduce wave energy and create habitats for limpets and sea weeds can reduce bucket and spade tourism

Question 55

What are the advantages and disadvantages of riprap and rock armour?

Answer 55

* cheap and protects beaches, however can be a nabigation hazard on beaches and reduce accesibility

Question 56

example, pros and cons of beach nourishment

Answer 56

Beach Nourishment at Dunwich, Suffolk: The process of replenishing eroding beaches with sand to counteract long-term coastal retreat,. Advantages: supports the sediment budget and reinforcing the natural littoral zone thus mitigating erosion in the long term; supports tourism and ecosystems such as sand dunes Disadvantages: The strategy is inherently unsustainable due to the cyclical need for replenishment

Question 57

example, pros and cons of Cliff Regrading and Drainage

Answer 57

Holderness Coast Involves altering the angle of the cliff face and installing drainage systems to reduce water retention and thus the risk of mass movement, such as slumping and rotational landslides. Advantages: Reduces the rate of cliff recession by addressing geomorphological processes, stabilizing the coastline; more cost-effective in areas where hard engineering is less feasible.

Question 58

example, pros and cons of dune stabilsation

Answer 58

Studland Bay, Dorset: The use of vegetation planting (e.g., marram grass) to promote dune growth and resilience against wind and water erosion, thus maintaining the natural coastal buffer. Advantages: Builds resilience through the concept of ecological coastal defense, enhancing both biodiversity and carbon sequestration; maintains natural sediment flow and provides a sustainable long-term solution. Disadvantages: Vulnerability to storm surges and sea-level rise, which may exceed the system’s ability to recover; limited effectiveness in highly urbanized or tourist-heavy areas due to trampling and human interference.

Question 59

Marsh creation

Answer 59

Allowing areas to flood and become salt marshes, reduces vullnerability but basically gives up on an area of land