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Geography A Level > Coasts > Flashcards

Coasts Flashcards

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1
Q

What is a coastal example of an input?

A

Precipitation and wind.

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2
Q

What is a coastal example of an output?

A

Ocean currents, rip tides, sediment transfer and evaporation.

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3
Q

What is a coastal example of energy?

A

Any energy associated with flowing water, the effects of gravity on cliffs and moving air (wind energy transferred to wave energy).

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4
Q

What is a coastal example of a store?

A

Beaches, sand dunes and nearshore sediment.

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5
Q

What is a coastal example of a transfer?

A

Wind blown sand, mass movement process, Littoral drift.

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6
Q

What is a coastal example of positive feedback?

A

Coastal management can lead to an increase in erosion elsewhere along the coast. Therefore hard engineering methods deprive other areas further down.

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7
Q

What is a coastal example of negative feedback?

A

When the rate of weathering and mass movement exceeds the rate of cliff foot-erosion a scree slope is formed. Over time, this apron extends up the cliff face protecting the cliff face from sub aerial processes (reducing the effects of weathering/mass movement).

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8
Q

Define Tombolo

A

A beach that forms between an island and the mainland.

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9
Q

Define Spit

A

A long, narrow accumulation of sand or shingle with one end attached to land and the other projecting out to sea or to a river estuary.

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10
Q

Define Offshore Bar

A

Elongated ridges and mounds of sand or gravel deposited beyond a shoreline by currents and waves.

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11
Q

Define Bar

A

Where a beach extends across an indentation in a coastline to join two headlands.

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12
Q

Define Berm

A

A ridge made of the biggest boulders thrown by large waves, found above the high tide marks.

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13
Q

What are the characteristics of a constructive wave?

A

Formation = Distance weather systems generate these waves in the open ocean.
Wave Form = Low, surging waves - with a long wavelength.
Wave Break = Strong swash, weak backwash.
Beach gained or lost? = Gained
Beach Profile = Usually associated with a gentle beach profile (over time build up the beach and make it steeper).

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14
Q

What are the characteristics of a destructive wave?

A

Formation = Local storms are responsible for these waves.
Wave Form = High plunging waves - with a short wavelength.
Wave Break = Weak swash, strong backwash.
Beach gained or lost? = Lost
Beach Profile = Usually associated with a steeper beach profile (over time they will flatten the beach).

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15
Q

What factors affect wave energy?

A
  • The strength of wind.
  • The duration of the wind.
  • The fetch of the waves. (How far it’s travelled)
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16
Q

With a neap tide and a spring tide, where is the Moon, Earth and Sun in position?

A
  • Neap tide: The Moon and the Sun are at right angles to each other, whilst the Earth is in line with the sun.
  • Spring tide: The Moon and the Sun are in line, whilst the Earth is either in front or behind the moon.
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17
Q

Which type of tide as the larger tidal range?

A

A spring tide has a larger tidal range, because gravitational pulls act together to create larger high tides and lower low tides. Whilst with a neap tide gravitational pulls act against each other to create lower high tides and higher low tides.

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18
Q

What is a rip current?

And how are they formed?

A

A rip current is a strong localised underwater current that occurs on some beaches, posing a considerable danger to swimmers and surfers.
They are formed by a build up of a series of plunging waves causing a temporary build up of water at the top of a beach. Met with resistance from the breaking waves, water returning down the beach is forced just below the surface following troughs and small undulations in the beach profile.

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19
Q

What type of coasts and landforms are found in high energy environments?

A

These coasts tend to be rocky coasts where the waves are powerful and the rate of erosion exceeds the rate of deposition. Landforms that appears on a high energy coastline tend to be headlands, cliffs and wave cut platforms.

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20
Q

What type of coasts and landforms are found in a low energy environment?

A

These coasts tend to be sandy and estuarine coasts as the waves are not very powerful and the rate of deposition exceeds the rate of erosion. Landforms that appears on a low energy coastline tend to be beaches, spits and coastal plains.

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21
Q

Define the process of littoral drift

A

Sediment is transported from one stretch of coastline (as an output) to another stretch of coastline (as an input).

22
Q

Define Sediment Cells

A

A sediment cell is a stretch of coastline usually bordered by two prominent headlands, where the movement of sediment is more or less contained.

23
Q

Define Sediment Budgets

A

The sediment budget (In principle) seeks to achieve a state of dynamic equilibrium where erosion and deposition are balanced.

24
Q

What is mechanical weathering and what types does it come in?

A

This is weathering that involves the break-up of rocks without any chemical changes taking places. It comes in the forms of:

  • Frost shattering
  • Wetting and drying
  • Salt crystallisation
25
Q

Define Frost Shattering (Also known as freeze-thaw)

A

This occurs when water enters a crack or joint in the rock when it rains and then freezes in cold weather. (When water freezes it expands in volume by 10%), Therefore exerting pressure onto the rocks which forces a crack to widen.

26
Q

Define Salt Crystallisation

A

This is when salt water evaporates and leaves salt crystals behind. These grow over time and exerts stresses into the rock, causing it to break up.

27
Q

Define Wetting and Drying

A

This is the frequent cycle of wet and hot weather. Rocks rich in clay expand when they get wet and contract as they dry, which can cause them to crack and break up.

28
Q

What is biological weathering and what types does it come in?

A

It’s the breakdown of rocks by organic activity. This can be due to:

  • Thin plant roots grow into small cracks in a cliff face (widens as the root grows).
  • Water running through decaying vegetation that becomes acidic which leads to increased chemical weathering.
  • Birds and animals dig burrows into cliffs.
  • Marine organisms are capable of burrowing into rocks or of secreting acids. (Such as piddocks)
29
Q

What is chemical weathering and what types does it come in?

A

Involves a chemical reaction where salts may be dissolved or a clay-like deposit may result which is then easily eroded. It comes in the forms of:

  • Carbonation
  • Oxidation
  • Solution
30
Q

Define Carbonation

A

This is rainwater that absorbs carbon dioxide from the air to form a weak carbonic acid. It then reacts with calcium carbonate in rocks (Such as limestone/chalk) to form calcium bicarbonate which is easily dissolved. (Colder the rainwater, the more carbon dioxide is absorbed)

31
Q

Define Oxidation

A

This is the reaction of rock minerals with oxygen, for example iron, to form a rusty red powder leaving rocks more vulnerable to weathering.

32
Q

Define Solution

A

The dissolving of rock minerals, such as halite.

33
Q

What is mass movement and what are the main types of mass movement?

A 
Mass movement is a process that represents a transfer of material from land to the beach or the sea. It depends on the angle of the slope, rock type, structure, vegetation cover and how wet it is.
There are several types, these are:
-Soil creep
-Mudflows
-Landslides
-Rockfall
-Landslip/slumping
-Runoff
-Solifluction
34
Q

What is soil creep?

A

Soil creep is an extremely slow form of movement of individual soil particles downhill. This process often involves particles rising towards the ground surface due to wetting/freezing and then returning vertically to the surface in response to gravity as the soil drys. This leads to trees and other objects on the land to be tilted downwards.

35
Q

What is a mudflow?

A

A mudflow involves earth and mud flowing downhill, usually over weak bedrocks such as clay, often after heavy rainfall. Water gets trapped within the rock, increasing pore water pressure, which forces rock particles apart and leads to slope failure. (Pore water pressure is a form of energy and is important in determining slope instability). Mudflows are often sudden and fast-flowing so can be dangerous.

36
Q

What is a landslide?

A

A landslide involves a block of rock moving very rapidly down a semi vertical slope, so it slides down. Unlike a mudflow, where the moving material becomes mixed, the moving block of material remains largely intact. They can be triggered by earthquakes or heavy rainfall (as it reduces friction due to heavy rainfall lubricating the surface). Like mudflows they are also rapid and can be dangerous.

37
Q

What is rockfall?

A

Rockfall involves the sudden collapse or breaking away of individual rock fragments at a cliff face. Rockfall is often triggered due to mechanical weathering or an earthquake. They usually fall down a steep or vertical cliff and once they fall off they bounce down and hit the surface they form scree (smaller rocks)

38
Q

What is runoff?

A

Runoff is a good illustration of the link between the water cycle and the coastal system. When overland flow occurs down a slope or cliff face, small particles are moved down slope to enter the littoral zone, forming a input into the sediment cell. It can be considered as a flow that transfers both water and sediment from the rock face to the beach and sea.

39
Q

What is solifluction?

A

This is similar to soil creep, but specific to cold periglacial environments. In the summer, it becomes extremely, saturated because it lies on top of impermeable frozen grounds. This sodden soil moves downhill by a combination of heave and flow.

40
Q

What is slumping or a landslip?

A

A landslip or the slumping process differs from a landslide as the slide surface is curved and not flat. It commonly occurs in weak and unconsolidated clays and sands, often when permeable rocks overlies impermeable rocks, causing a build up of pore water pressure. They are characterised by a large break of slope and formation of a scar which slowly sinks into the ocean or beach.

41
Q

What are the main types of coastal erosion?

A
  • Hydraulic Action
  • Corrasion
  • Abrasion
  • Solution (Corrosion)
  • Wave Quarrying
  • Attrition
42
Q

Define Hydraulic Action

A

This is the sheer force of water that crashes against the coastline, when a wave advances air can be trapped and compressed either in joints and crack in the rock or between the breaking wave and the cliff. When the wave retreats the compressed air expands weakening the joints and cracks in the cliff side.

43
Q

Define Corassion

A

When waves advance, they pick up sand and pebbles from the seabed, a temporary store. When they break off the cliff, the transported material is hurled at the cliff, chipping away more of the rocks.

44
Q

Define Abrasion

A

Abrasion is where sediment is dragged up and down or across the shoreline, eroding and smoothing rocky surfaces.

45
Q

Define Wave Quarrying

A

This is the action of waves breaking against unconsolidated material such as sands and gravels. Waves scoop out the loose materials from the bottom of the cliff side.

46
Q

Define Attrition

A

This is when sediment has been taken off the cliff side and hits other sediment particles in the sea breaking them down further.

47
Q

What factors can affect the nature and rate of coastal erosion?

A
  • Type of waves
  • Rock type
  • Geological structure
  • Presence (or absence) of a beach
  • Coastal management
  • Sub aerial processes
48
Q

What are the four types of coastal transportation processes?

A
  • Traction (The rolling of coarse sediment along the sea bed that is too heavy to be picked up and carried by the sea).
  • Saltation (Sediment that has bounced along the seabed, light enough to be picked up or dislodged but too heavy to remain within the flow of the water).
  • Suspension (Smaller and lighter sediment that is picked up and carried within the flow of the water).
  • Solution (Chemicals dissolved in the water, transported and precipitated elsewhere).
49
Q

What are the coastal morphology characteristics?

A
  • Strata (Layers of rocks).
  • Bedding Planes (Horizontal, natural breaks in caused by gaps in time during periods of rock formations).
  • Joints (Vertical fractures caused either by contraction as sediment dry out, or by earth movements).
  • Folds (Formed by pressure during tectonic activity, which makes rocks buckle and crumple).
  • Faults (Formed when the stress/pressure to which a rock is subjected, exceeds its initial strength, causing it to fracture. Fault then slips/move along fault planes).
  • Dip (Refers to the angle at which rock strata lies).
50
Q

What are the formations formed (In order) of eroding a headland?

A
  • Crack
  • Cave
  • Arch
  • Stack
  • Stump
  • Submerged Stump

Geography A Level (6 decks)

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