1.2 How are coastal landscapes developed?

Question 1

1.2 How are coastal landforms developed?

Answer 1

Coastal landforms develop due to a variety of interconnected climatic and geomorphic processes.

Question 2

Discordant coastline: What is it and what can it give rise to?

Answer 2

In this type of coastline, the layers of rock are perpendicular to the direction of the coastline. Bays and headlands begin to form.

Question 3

Concordant coastline: What is it and what can it give rise to?

Answer 3

In this type of coastline, the layers of rock are parallel to the direction of the coastline.
The outer hard rock provides a protective barrier to erosion of the softer rocks further inland. Sometimes the outer hard rock is punctured, allowing the sea to erode the softer rocks behind. This creates a cove, a circular area of water with a relatively narrow entrance from the sea.

Question 4

Geomorphic processes: What are they and what examples are there?

Answer 4

the natural forces that reshape the Earth’s surface over time

-Weathering (Physical or mechanical, Chemical, Biological)
-Mass movement (Rock fall, Slides)
-Erosion (Wave processes)
-Transportation (Wave processes)
-Deposition (Wave processes)

Question 5

Weathering definition and examples

Answer 5

Energy used to produce physically or chemically altered materials from the surface or near surface rock. In coastal environments some types of weathering are particularly significant and influence the formation of coastal landforms.
Physical/Mechanical
Biological
Chemical

Question 6

Physical or mechanical weathering

Answer 6

Physical weathering breaks rocks into smaller fragments without chemical change. It increases surface area for further weathering and contributes to sediment supply. However, in coastal areas like western Europe, milder temperatures limit freeze-thaw weathering due to fewer sub-zero fluctuations.

Question 7

Freeze-thaw (physical or mechanical weathering)

Answer 7

Water enters cracks/joints in rock.
Temperature drops below 0°C — water freezes.
Ice expands by ~9%, widening the crack.
Temperature rises — ice melts.
Repeated cycles weaken the rock.
Rock breaks into angular fragments
Note: Less effective in mild coastal climates with fewer freeze-thaw cycles.

Question 8

Pressure release (physical or mechanical weathering)

Answer 8

Overlying rock is eroded or removed.
Underlying rock expands due to reduced pressure.
Surface layers crack and fracture parallel to the rock face.
Sheets of rock peel off (exfoliate).
Broken fragments contribute to sediment at the base.

Question 9

Thermal expansion (physical or mechanical weathering)

Answer 9

Rock heats up in the day and expands.
Rock cools at night and contracts.
Daily (diurnal) expansion and contraction cause stress.
Stress weakens rock structure over time.
Rock eventually fractures and breaks apart.
Note: Most effective in arid, high-temperature environments.

Question 10

Salt crystallisation (physical or mechanical weathering)

Answer 10

Saline water enters pores or cracks in the rock.
Water evaporates, leaving salt crystals behind.
Crystals grow and exert pressure on surrounding rock.
Repeated cycles widen cracks.
Rock breaks apart due to internal stress.
Common in dry or salt-rich coastal areas
Sodium sulphate and sodium carbonate are particularly effective, expanding by about 300 per cent in areas of temperatures fluctuating around 26-28ºC.

Question 11

Chemical weathering

Answer 11

Chemical weathering involves reactions between water and minerals in rock, breaking it down or altering its composition. It produces weak residues that are easily removed by erosion or transport.

Question 12

Van’t Hoff’s Law and chemical weathering

Answer 12

A 10ºC rise increases reaction rates 2.5× (up to 600ºC), so chemical weathering is fastest in moist tropical climates and slowest in cold regions. However, carbonation is more effective in cold water, as CO₂ is more soluble.
However, it is worth noting that carbonation can be more effective in low temperatures as carbon dioxide (CO2) is more soluble in cold water than in warm water.

Question 13

Oxidation (chemical weathering)

Answer 13

Some minerals in rocks react with oxygen (O2), either in the air or in water. Iron is especially susceptible to this process. It becomes soluble under extremely acidic conditions and the original structure is destroyed. It often attacks the iron-rich cements that bind sand grains together in sandstone.

Question 14

Carbonation (chemical weathering)

Answer 14

Rainwater combines with dissolved carbon dioxide from the atmosphere to produce a weak carbonic acid.
This reacts with calcium carbonate in rocks such as limestone to produce calcium bicarbonate, which is soluble.

Question 15

Solution (chemical weathering)

Answer 15

Some salts are soluble in water. Other minerals, such as iron, are only soluble in very acidic water, with a pH of about 3. Any process by which a mineral dissolves in water is known as solution

Question 16

Hydrolysis (chemical weathering)

Answer 16

Hydrolysis is a chemical reaction where acidic water reacts with minerals in rock (like feldspar), forming clay minerals and soluble salts. This alters the rock’s chemical structure, weakening it and making it more prone to erosion.

i.e. Silicates + Water -> clay
Feldspar in granite + hydrogen in water -> China clay

Question 17

Hydration (chemical weathering)

Answer 17

Water molecules are added to rock minerals.
This forms new minerals (e.g. anhydrite + water → gypsum).
The new minerals have a larger volume.
Expansion (up to 0.5%) causes stress in the rock.
Surface layers flake off due to repeated expansion.

Question 18

Biological weathering

Answer 18

Biological weathering may consist of physical actions such as the growth of plant roots or chemical processes such as chelation by organic acids.

Question 19

Tree roots (biological weathering)

Answer 19

Tree roots grow into cracks and joints in rocks.
They exert outward pressure, widening the cracks.
This process is similar to freeze-thaw weathering.
When trees topple, their roots can lift rock and soil, exposing them to further weathering.
Burrowing animals may have a similar effect, especially on cliffs.

Question 20

Organic acids (biological weathering)

Answer 20

Organic acids are produced by decomposing plant and animal matter.
These acids make soil water acidic.
The acidic water reacts with minerals in rocks through chelation.
Blue-green algae and molluscs can also produce acids, contributing to small surface hollows and oxide formation on rocks.

Question 21

Mass movement definition

Answer 21

Mass movement occurs when gravity exceeds friction, causing slope material to move.
In coastal landscapes, this typically involves cliffs, where material is transferred to the shore.
Key processes include rock fall and slides, which add to the sediment budget.

Question 22

Rock fall (mass movement)

Answer 22

On cliffs of 40º or more, especially if the cliff face is bare, rocks may become detached from the slope by physical weathering processes. These then fall to the foot of the cliff under gravity. Wave processes usually remove this material, or it may accumulate as a relatively straight, lower angled scree slope.

Question 23

Slides (mass movement)

Answer 23

Slides are linear mass movements along a straight slip plane (e.g. fault or bedding plane).
They often occur due to undercutting by wave erosion at the cliff base, removing support.
This leads to a downward movement of material along the plane.
Slides add sediment to the coastal sediment budget.

Question 24

What are slumps and how do they occur in coastal landscapes?

Answer 24

Slumps are rotational mass movements along a curved slip plane.
They commonly happen in weak rocks, like clay, which become heavier when wet.
A layer of sand over clay encourages slumps as rainwater infiltrates the sand but not the clay, increasing pore pressure.
The added pressure causes the clay to slump downwards, contributing material to the coast.

Question 25

Waves processes

Answer 25

-Erosion (Abrasion (or corrasion), Attrition, Hydraulic action, Pounding, Solution (or corrosion)) -Transportation (Solution, Suspension, Saltation, Traction) -Deposition

Question 26

Waves processes definition

Answer 26

Waves are a source of energy that shape landforms through geomorphic processes. They also supply sediment to the system, either depositing it or transporting it along the coast. -Erosion -Transportation -Deposition

Question 27

Erosion (waves processes)

Answer 27

-Abrasion (or corrasion) -Attrition -Hydraulic action -Pounding -Solution (or corrosion)

Question 28

Abrasion (or corrasion) (Erosion (waves processes))

Answer 28

When waves armed with rock particles scour the coastline; rock rubbing against rock.

Question 29

Attrition (Erosion (waves processes))

Answer 29

Occurs when rock particles, transported by wave action, collide with each other and with coastal rocks and progressively become worn away. They become smoother and more rounded as well as well as smaller, eventually producing sand.

Question 30

Hydraulic action (Erosion (waves processes))

Answer 30

Occurs when waves break against a cliff face, and air and water trapped in cracks and crevices becomes compressed. As the wave recedes the pressure is released, the air and water suddenly expands and the crack is widened. The average pressure exerted by breaking Atlantic waves is 11,000 kg per m³.

Question 31

Pounding (Erosion (waves processes))

Answer 31

Occurs when the mass of a breaking wave exerts pressure on the rock causing it to weaken. Forces of as much as 30 tonnes per m² can be exerted by high-energy waves.

Question 32

Solution (or corrosion) (Erosion (waves processes))

Answer 32

Involves dissolving minerals like magnesium carbonate minerals in coastal rock. However, as the pH of sea water is invariably around 7 or 8 this process is usually of limited significance unless the water is locally polluted and acidic. Even then, only coastal rocks containing significant amounts of soluble minerals are likely to be affected by this.

Question 33

Transportation (waves processes)

Answer 33

-Solution -Suspension -Saltation -Traction

Question 34

Transportation (waves processes) definition

Answer 34

transportation is the movement of sediment (such as sand, gravel, and pebbles) along the coast by wave action, currents, and wind.

Question 35

Solution (Transportation (waves processes))

Answer 35

Minerals that have been dissolved into the mass of moving water. This type of load is invisible and the minerals will remain in solution until water is evaporated and they precipitate out of solution.

Question 36

Suspension (Transportation (waves processes))

Answer 36

Small particles of sand, silt and clay can be carried by currents; this accounts for the brown or muddy appearance of some sea water. Lager particles can also be carried in this way, perhaps during storm events.

Question 37

Saltation (Transportation (waves processes))

Answer 37

This is a sense of irregular movements of material which is too heavy to be carried continuously in suspension. Turbulent flow may enable sand-sized particles to be picked up (entrained) and carried for a short distance only to drop back down again. Similarly, other particles may be dislodged by the impact, allowing water to get beneath them and cause entrainment.

Question 38

Deposition (waves processes)

Answer 38

Deposition is the process where material carried by waves is laid down due to a loss of energy, typically from a decrease in velocity and/or water volume

Question 39

What examples of Wave Deposition are there?

Answer 39

- Sediment accumulates faster than it is removed - Waves slow down right after breaking - Water briefly stops moving at the top of the swash - Backwash percolates into the beach, reducing energy - In low-energy environments like sheltered bays or estuaries

Question 40

Traction (Transportation (waves processes))

Answer 40

The largest particles in the load may be pushed along the sea floor by the force of the flow. Although this can be called rolling, again the movement is seldom continuous. Large boulders may undertake a partial rotation before coming to rest again.

Question 41

Settling velocity

Answer 41

The velocity at which sediment particles are deposited. The larger and heavier particles require more energy to transport them. As flow velocity decreases, the largest particles being carried are deposited first and so on, sequentially until the finest particles are deposited

Question 42

Fluvial processes definition

Answer 42

Fluvial processes are the physical actions of rivers and streams that shape the landscape. They include: -Erosion -Transportation -Deposition

Question 43

Erosion (fluvial processes): What's similar to waves and how is sediment derived from this?

Answer 43

Fluvial erosion is the wearing away of the riverbed and banks, mainly in the upper catchment. Rivers use similar erosional processes to waves, with most channel erosion occurring during high-flow, high-energy events. Sediment is also derived from weathering and mass movement processes that result in material moving into river channels from the valley sides.

Question 44

What are the four main fluvial transportation processes?

Answer 44

Traction – Large boulders rolled along the bed Saltation – Small pebbles bounced along the bed Suspension – Fine material carried in the water Solution – Dissolved minerals transported invisibly These processes are similar to those used by waves.

Question 45

When and why does fluvial deposition occur?

Answer 45

As rivers enter the sea, there is a noticeable reduction in their velocity as the flowing water moving through the channel enters the relatively static body of sea water . Indeed, tides and currents may be moving in the opposite direction to the river flow, providing a major resistance to its forward movement. Available energy is reduced and so some, or all, of the river's sediment load is deposited. As the reduction in energy is progressive, deposition is sequential, with the largest particles being deposited first and the finest being carried further out to sea. Flocculation also occurs: clay particles clump in salt water due to electrical charges, making them heavier so they sink to the seabed

Question 46

Aeolian processes definition

Answer 46

Aeolian processes are caused by the action of wind, especially in exposed coastal areas with dry, sandy surfaces. Winds are most effective when blowing onshore Aeolian processes include erosion, transportation, and deposition of sediment

Question 47

Erosion (aeolian processes): how can they erode it?

Answer 47

Deflation – lifting and removal of loose particles Abrasion – sand particles blown against surfaces (only effective up to 1 m high) Attrition – particles collide in air, becoming smaller and rounder Erosion is most effective when: Wind speeds exceed 40 km/h Sand is dry (wet sand sticks due to cohesion) Erosive force increases exponentially with wind velocity

Question 48

How is sediment transported by wind in aeolian processes?

Answer 48

Wind transports sediment similarly to rivers (excluding solution): Surface creep – large grains (0.26–2 mm) rolled along the ground Saltation – medium grains (0.15–0.25 mm) bounce along Suspension – only the finest particles (0.05–0.14 mm) lifted into the air 🔄 Transport occurs even at low wind speeds (as low as 20 km/h)

Question 49

Deposition (aeolian processes)

Answer 49

Aeolian deposition occurs when wind velocity drops, reducing energy: Caused by increased surface friction from vegetation or uneven ground Often happens inland, where surfaces are rougher than open beach or sea 📉 As wind slows, heavier particles are dropped first

Question 50

What are cliffs and how are they formed?

Answer 50

Cliffs are steep, near-vertical landforms formed at coastlines where marine erosion and subaerial processes operate. Powerful destructive waves erode the base of the coastline through hydraulic action (compression of air in cracks), abrasion (sediment scraping rock), and solution (dissolving minerals like limestone). These processes carve out a wave-cut notch at the base of the cliff, undercutting the rock above. As erosion continues, the overhanging rock becomes unstable and eventually collapses due to gravity. This causes the cliff to retreat inland, and the process repeats over time, leaving behind a wave-cut platform Weathering (e.g. freeze-thaw, salt crystallisation) and mass movement (e.g. rockfalls, slumping) further contribute to cliff retreat by weakening the rock face. Geology plays a role: speed of cliff formation

Question 51

What are Shore Platforms and how are they formed?

Answer 51

Shore platforms (also known as wave-cut platforms) are gently sloping, often smooth rock surfaces found at the base of retreating cliffs. They are formed through the repeated action of marine erosion at the base of a cliff by destructive waves. Hydraulic action, abrasion, and solution erode a wave-cut notch into the cliff base during high-energy wave conditions. As undercutting continues, the cliff becomes unstable and collapses, causing the cliff to retreat inland. The collapsed material is broken down by waves and carried away, exposing a flat or gently sloping rocky surface. Over time, this surface is smoothed and deepened by abrasion and wetting and drying cycles. Erosion is most effective at high tide as water levels are constant for longest, so the platform only extends as far as wave energy can reach, creating a limit to its growth. Weathering (e.g. salt crystallisation, freeze-thaw) and biological activity (e.g. algae) further break down rock on the platform surface.

Question 52

What are Bays and headlands and how are they formed?

Answer 52

Bays and headlands typically form adjacent to each other on coastlines where bands of rock with differing resistance to erosion lie perpendicular to the shoreline. This forms a discordant coastline, where softer rocks (e.g. clays) are eroded more quickly, forming bays, while harder rocks (e.g. limestone or chalk) remain as headlands. The width of bays is determined by the width of the weaker rock band, while depth depends on the contrast in erosion rates between soft and hard rocks. Conversely, on concordant coastlines, where rock layers run parallel to the shoreline, resistant rock (e.g. Portland limestone) may shield weaker rocks behind it, resulting in a straighter coastline. However, weaknesses in the resistant rock (e.g. fault lines) can be exploited by erosion to form small coves, such as Lulworth Cove on the Isle of Purbeck. As waves approach irregular coastlines, wave refraction occurs: waves slow in shallow water around headlands and speed up in deeper water in bays. This causes wave energy to focus on headlands (where orthogonals converge), erosion on headlands, deposition on bays

Question 53

How do caves arches stacks and stumps form?

Answer 53

Caves, arches, stacks, and stumps form through the continuous process of erosion acting on headlands along the coastline. The process begins with waves attacking weaknesses in resistant rock (e.g. joints, faults, or cracks) on the headland. Hydraulic action (compression of air in cracks) and abrasion (grinding by sand and pebbles) widen and deepen these cracks, forming caves. Caves eventually break through the headland to form arches, creating a gap in the rock. The roof of the arch becomes more vulnerable to erosion and weathering (e.g. freeze-thaw). Over time, the roof of the arch becomes increasingly weakened and eventually collapses, leaving a stack — a vertical column of rock. The stack is further eroded by waves and weathering, and over time, it is reduced to a stump — a smaller remnant of the original rock.

Question 54

What are Geos and how are they formed?

Answer 54

Geos are narrow, steep-sided inlets or caves formed by erosion along a line of weakness in the rock, typically faults or joints. Hydraulic action (the compression of air and water into cracks) and abrasion (erosion caused by particles carried by waves) widen and deepen the crack over time. Geos are horizontal features, where the cave extends into the headland, and they typically do not have an opening at the top. Erosion works particularly effectively in limestone and chalk coasts because these rocks are more susceptible to erosion by wave action. The wave energy focuses on the cracks, progressively eroding them and creating an inlet that can form a geo. Over time, geos can grow larger as continued wave action deepens and widens the inlet. Geos are often found on coastal headlands where harder rock (which forms the headland) meets softer rock.

Question 55

What are Blowholes and how are they formed?

Answer 55

Blowholes are formed when waves enter a cave or crack in the rock, and hydraulic pressure builds up inside the cave. The presence of a top opening in the cave allows the water and air to be forced out through the top, creating a blowhole. Wave action repeatedly forces air and water into the cave, and the pressure causes the water to be expelled with significant force. Hydraulic action causes the cave to widen and deepen over time, enhancing the blowhole's ability to expel water. Blowholes are vertical features, typically found in permeable rocks like limestone or chalk, which are susceptible to erosion. Blowholes are more likely to form in areas where waves and water have access to an underlying cave system with an opening at the top. As the blowhole enlarges, water can be expelled in dramatic sprays, especially during high-energy wave conditions.

Question 56

How are beaches formed?

Answer 56

Beaches form through the accumulation of material, primarily sand, pebbles, or shingle, that has been transported and deposited by waves and currents. Wave action is the main force behind beach formation, with constructive waves playing a key role in building up the beach. These waves have a gentle slope, and their swash (the wave that moves onto the shore) carries sediment onto the beach. Sediment transportation occurs in longshore drift, where waves approach the coast at an angle, moving sediment along the shoreline. The material is then deposited when the wave energy decreases, especially in sheltered areas. The swash pushes sediment up the shore, while the backwash moves it back down, often sorting the material by size. Larger particles are usually deposited closer to the shore, forming the berm. Beach material can vary, with shingle beaches formed by larger particles like pebbles, and sandy beaches forming from finer, more easily transported material. Over time, the composition and shape of the beach can be influenced by factors such as tides, wave energy, and sediment supply, leading to different types of beaches (e.g., spit beaches or bar beaches). Storm conditions can temporarily disrupt the beach profile, causing erosion and the redistribution of material. However, the long-term process of deposition tends to restore the beach

Question 57

What's the interesting thing about Spits/Tombolos/Salt Marsh/Tombolos?

Answer 57

Spits are formed first when longshore drift deposits sediment along the coastline. Then depending on othjer factors like coastal geography, wave direction and sediment transportation, one of the other 3 are formed

Question 58

How are Spits formed?

Answer 58

Spits are long, narrow ridges of sand or shingle that extend from the land into the sea, formed by the process of longshore drift. Longshore drift occurs when waves approach the coastline at an angle, moving sediment along the shore in a zig-zag pattern. The sediment is carried by the swash up the beach and then pulled back by the backwash, moving along the coastline. When the coastline bends or changes direction, the longshore drift continues to move sediment forward, but at the point where the coastline curves, the waves lose their energy. This results in the accumulation of material, forming a spit. Spits are often curved at the end due to changes in the direction of the waves and currents/secondary prevailing wind. The curve forms because the sediment is deposited in a sheltered area where wave energy is weaker. Spits can extend for varying lengths depending on factors like sediment supply, wave energy, and coastline shape, and are generally lowlying and vulnerable to sea level rise Spits are dynamic (constantly changing), As long as deposition > erosion it can exist. Storms can remove ALOT of sediment away

Question 59

How are Onshore bars created?

Answer 59

FIRST BIT: EXPLAIN SPIT Onshore bars can develop if a spit continues to grow across an indentation, such as a cove or bay, in the coastline until it joins onto the land at the other end . This forms a lagoon of brackish water on the landward side These bars can be formed in embayments or areas with a slight curvature in the coastline, where waves lose energy more rapidly and deposition is more likely.

Question 60

How are Tombolos formed?

Answer 60

FIRST BIT: EXPLAIN SPIT Tombolos are formed when a spit extends from the mainland and connects to an island. The formation of a tombolo involves longshore drift depositing sediment until it bridges the gap between land and island.

Question 61

How are Salt Marshes formed?

Answer 61

FIRST BIT: EXPLAIN SPIT Salt marshes form in sheltered coastal areas with low wave energy, such as behind spits or in estuaries. Fine sediments like silt and clay accumulate and allow the growth of salt-tolerant plants (eelgrass and spartina). Over time, these marshes build up and can become important wildlife habitats and act as natural flood barriers.