Coastal landscapes Flashcards

Question

Thermal expansion

Answer 1

Rocks expand when heated and contract when cooled. If they are subjected to frequent cycles of temperature change then the outer layer may crack and flake off. This is also as insolation weathering, although experiments have cast doubts on its effectiveness unless water is present

Answer 2

Solutions of salt can seep into the pore spaces in porous rocks. Here the salt precipitate, forming crystals. The growth of these crystals creates stress in the rock, causing it to disintegrate. Sodium sulphate and sodium carbonate are particularly effective, expanding by 300% in areas of temperatures fluctuating around 26-28°C

Answer 3

- Oxidation - Carbonation - Solution - Hydrolysis - Hydration

Answer 4

Some minerals in rocks react with oxygen, 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. Oxygen often attacks the iron-rich cements that bind sand grains together in sand stone

Answer 5

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. This processes is reversible and precipitation f calcite happens during evaporation of calcium rich water in caves to form stalactites and stalagmites

Answer 6

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, although mineral-specific processes, such as carbonation, can be identified.

Answer 7

This is a chemical reaction between rock minerals and water. Silicates combine with water, producing secondary minerals such as clays. Feldspar in granite reacts with hydrogen in water to produce kaolin (China clay)

Answer 8

Water molecules added to rock minerals create new minerals of a larger volume. This happens when anhydrite takes up water to form gypsum. Hydration causes surface flaking un many rocks, partly because some minerals also expand by about 0.5% during the chemical change because they absorb water

Answer 9

- Tree roots - Organic acids

Answer 10

- Tree roots grow into cracks or joints in rocks and exert outward pressure. This operates in a similar way and with similar effects to freeze-thaw. When trees topple, their roots can also exert leverage on rock and soil, bringing them to the surface and exposing them to further weathering - Burrowing animals have a similar effect. This may be particularly significant on cliff tops and cliff faces

Answer 11

Organic acids produced during decomposition of plant and animal litter cause soil water to become more acidic and react with some minerals in a process called chelation. Blue-green algae can have a weathering effect, producing a shiny film of iron and manganese oxides on rocks. On shore platforms, molluscs may secrete acids which produce small surface hollows in the rock.

Answer 12

These processes refer to the movement of material (regolith) down a slope. They are sub-aerial processes (above ground) and rely on slope angle, particle size, temperature and saturation.

Answer 13

Process - Landslides Description - Cliffs made of softer rocks slip when lubricated by rainfall Process - Rockfalls Description - Rocks undercut by the sea or slopes affected by mechanical weathering Process - Mud flows Description - Heavy rain causes fine material to move downhill Process - Slumping Description - Where soft material overlies resistant material and excessive lubrication takes place Process - Soil creep Description - Very slow movement of soil particles downslope

Answer 14

Breaking waves can erode the coastline through a range of processes. Waves can also supply sediment to the system which is either deposited or transported

Answer 15

Process - Hydraulic action Description - Wave pounding - The force of water on the rocks Process - Pounding/ wave quarrying Description - Breaking wave exerts pressure on the rock, air is trapped in cracks in a cliff face, as the water pulls back air is released under pressure. The rock face is weakened over time Process - Abrasion Description - Sand, shingle and boulders picked up by the sea and hurled against the cliff Process - Attrition Description - The wearing down of rocks and pebbles as they rub against each other, making them smaller and round Process - Solution/ corrosion Description - Where fresh water mixes with salt water, acidity may increase and carbon-based rocks are broken down

Answer 16

- Traction - Saltation - Suspension - Solution - Long shore drift

Answer 17

Large boulders rolled along the seabed

Answer 18

Small stones bounced along the seabed

Answer 19

Very small particles carried in moving water

Answer 20

- Waves approach the shore at the angle of prevailing wind, swash moves materials up the beach in the same direction as the wave, backwash moves the material back down the steepest gradient - usually perpendicular to where is picked to where it is picked up by the next incoming wave

Answer 21

Deposition occurs when velocity and/or volume of water decreases and energy is reduced. Deposition takes place in coastal environments when: - Sediment accumulation exceeds removal - Waves slow after breaking - Backwash water percolates into beach material - There is a sheltered area such as an estuary

Answer 22

- Water in a river system interacts with its environment, shaping landscapes and transporting materials - These are significant in estuarine environments. Fluvial erosion, weathering and mass movement processes supply sediment to river channels. This is then transported downstream and deposited as rivers enter the sea - Mudflats and saltmarshes are landforms that are form in sheltered low-energy coastlines. They are associated with large tidal ranged where powerful currents transport large quantities of fine sediment

Answer 23

- Erosion, transport and deposition by the wind - Coastal landscapes are significantly influenced by winds. Wind picks up sand particles and moves them, a processes known as deflation. Attrition on land by windblown particles is also effective over long distances. When the wind speed falls, material carried by the wind will be deposited

Answer 24

Headlands and bays are formed where there are bands of different rock with different resistant's to erosion. - Where these bands of rock lie perpendicular to the coastline, the weaker rock erodes more quickly, forming a bay, and the hard rock is left as a headland. This is a DISCORDANT coastline - Where the bands of rock lie parallel to the coastline, the hard rock lies on the seaward side of the coastline and coves develop when a weakness is eroded landwards. This is a CONCORDANT coastline

Answer 25

The processes of cliffs and wave cut platforms: 1. High waves concentrate erosion at the base of the cliff 2. The cliff is undercut forming a wave cut notch 3. Overtime the undercut cliff collapses and the cliff face retreats 4. A gently sloping forefront to the cliff is left - a wave-cut platform 5. The wave cut platform is cut into by abrasion and also eroded by hydraulic and chemical action. When exposed it will be weathered by sub-aerial processes 6. Overtime wave break further out to sea, wave energy dissipates and erosion is reduced.

Answer 26

Geos are narrow steep sided inlets formed on a coastline where there is a weakness (joint or fault) in the rock which is exposed by erosion possesses such as hydraulic action. If geos become enlarged by continual erosion and the roof collapses and they become a blowhole, appearing as a vertical shaft the reaches the cliff top

Answer 27

The formation of a cave, arch, stack and stump: 1. Weaknesses such as a joint or fault in resistant rock are attacked by waves 2. Erosion (hydraulic action, abrasion, wave quarrying) widens the weakness and undercuts the base to form a cave 3. Erosion processes concentrate on the headland. Often a cave meets another cave and a hole through the headland is opened up to form an arch 4. As the cliff face recedes a wave cut platform develops. The arch will eventually collapse leaving an isolated stack 5. The sea attacks the base of the stack. Eventually a wave cut notch will undercut the stack and a raised portion of the wave-cut platform will be left as a stump

Answer 28

- Swash-aligned coastlines develop where there is minimal longshore drift, the coastline is irregular and waves hit headlands - Drift aligned coastlines are parallel to the direction of longshore drift, waves at an angle to the beach 1. Longshore drift carries material (e.g. W to E) 2. Where the coastline changes to N/S alignment there is a build up of sand and shingle 3. Material builds eastwards to form a spit 4. Refraction carries material into sheltered water and second-most dominant wind adds to curvature of the spit 5. On the sheltered area between land and sea the low energy leads to deposits of silt and clay and a salt marsh develops 6. A spit that joins an island to a mainland is a tombolo. If a spit develops across a bay and there is no strong flow of water from the landward side, a bar is formed 7. Formed by the accumulation of sand and shingle deposited between high and low tides. Features: Storm beach, berms, cusps, ripples, breached ridges

Answer 29

- Beaches are the most common depositional landform. Material consists of sand or shingle (a mix of pebbles and cobbles) from source such as cliff erosion, rivers and the sea bed - Beaches are dynamic landforms and the profile will change over time according to wind strength. An equilibrium profile develops with a balance between erosion and deposition.

Answer 30

- A spit is formed by LSD deposits sediment after a change in the dominant wind direction which causes a formation of a long thin strip of deposited material past the end of the beach - The once the energy of the secondary wind slows down then it may form a recurved hook - This is the same processes as a tombola however it joins onto an island at the end

Answer 31

Form a flat landscape low-lying estuarine areas. They form over time in three distinct stages each showing a specific ecology Stage 1: Description - Pioneer species develop (halophytes - salt tolerance) Ecology - Glasswort, cord grass. These plants slow the movement of water and encourage sedimentation. Their roots stabilise mud Stage 2: Description - Soil develops, lower salinity, current slows, more deposition, organic matter produced. The marsh increases in height. Biodiversity and plant cover increases Ecology - Sea aster, sea lavender and marsh grass Stage 3: Description - Mud level rises, land rises above sea level, rushes and reeds grow. Salinity levels fall and soil develops Ecology - Climax vegetation: ash, alder and oak

Answer 32

Energy inputs: - Wind - Wave - Current - Tides High energy coastlines: - Predominantly strong wave power - High waves - Strong prevailing winds - Long length of fetch - Erosion greater than deposition - Landforms: Wave cut platforms Low energy coastlines: - Low wave energy - Waves spread out, energy is dissipated - Low waves - Deposition greater than erosion - Low tidal range - Landforms: Beaches and spits

Answer 33

It is a global change in the volume of sea water resulting from a rise or fall in the level of the sea itself, e.g. caused by the retreat of ice following a glacial period. Eustatic changes are influenced by variations in mean global temperatures

Answer 34

Is a local change in sea level resulting from the land rising or falling relative to the sea e.g. tectonic movement

Answer 35

- Climate change can lead to a sea level fall - Fall in global temps --> more precipitation in the form of snow --> snow turns into ice --> more water stored on the land as solid ice rather than liquid water, which is returned to the oceans - Cold water has a lower volume

Answer 36

- Land forms shaped by wave processes when the sea level was higher are exposed when sea levels fall. They may be found inland from present coastlines. Such as landforms include raised beaches, marine terraces and abandoned cliffs. Raised beaches and abandoned cliffs - Beaches and cliff lines elevated above sea level and exposed following deglaciation and the unloading of ice sheets. Marine terraces - Where an expanse of gently sloping formerly submerged land has been exposed by uplift of the lowering of sea levels

Answer 37

- As they are now exposed and above the waterline, these landforms are now effected by weathering and mass movement processes e.g. Freeze thaw - In post glacial periods when the climate is wetter and warmer, vegetation develops. Warming is predicted in the future and this could lead to chemical and biological weathering becoming more influential - If the rise in temperature is enough for sea level to rise, these emergent features may then become closer to the coastline and wave processes will again be an influential factor

Answer 38

Climate change can lead to a sea level rise: - Warmer water has more volume - Rise in global temperatures --> Melting of ice stores on the land --> increase in the volume of water in the oceans --> sea level rise - The 1.1°C rise in mean global temperature since pre-industrial times has resulted in a mean sea level rise of 15-25cm since 1901

Answer 39

The main influences of a rise in sea level is the submergence of features such as river valleys - rias , and glacial valleys - Fjords. Shingle beaches also appear where former coastal sediment is pushed onshore by wave action Shingle beaches - This is where river sediment previously deposited on the continental shelf were above sea level. Rising sea levels over the past 20,000 years have swept up the sediment and deposited it on present day coasts Estuaries - Drowned, shallow, lowland river valleys Rias - Drowned, incised river valleys on upland coasts Fjords - Drowned glacial troughs

Answer 40

- Rias and fjords can be modified by wave processes. The height and intensity of the waves will increase if there are more storm conditions as a result of future climate change - The valley sides will be modified by sub aerial weathering processes e.g. mechanical weathering - Shingle beaches will be modified by processes that transport sediment such as long shore drift

Answer 41

- Rias are river valleys that have been flooded by the rise in sea level - As rias were river valleys they tend to have gently sloping sides. The rivers paleo-course and floodplain are submerged by the sea providing a relatively shallow cross section and a uniform long section - Usually they have irregular winding course that follows the course of the original river and its tributaries

Answer 42

- Fjords are glacial U-shaped valleys that have been flooded by a rise in sea level - In areas where glaciation carved out deep U-shaped valleys relatively near to the coast, rising sea level forms fjords - Fjords are much deeper and narrower than rias and can extend back inland for a hundred miles or more - In cross section the flooded U-shape valley can be clearly seen. In long section the fjord in often shallower nearest the sea as glacial erosion was weakest here as the ice was thinnest

Answer 43

- During the Devensian glacial period when the sea level was much lower, fluvial sediment built up in these paleo-coastal areas. This was joined by glacial sediment when the ice melted that was deposited in large quantities in outwash plains - As the sea level started to rise from 25,000 years BP this sediment was pushed onshore by wave action - In the UK during the Flandrian Transgression, large quantities of sediment where moved around Abbotsbury and Portland in Dorset forming chesil Beach - Shingle beaches are likely to be damaged by erosion due to increase waring of the climate. This is because sea level will rise further and there will be and increase in storm frequency. Both factors will increase the magnitude of marine erosion

Coastal landscapes Flashcards

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