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Case studies: Coastal systems > Coastal Processes > Flashcards

Coastal Processes Flashcards

1
Q

The four sources of energy in coasts are:

A
  1. Wind
  2. Waves
  3. Tides
  4. Currents
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2
Q

What is a high energy coast and what are its features?

A

Receive high inputs of energy through large, powerful waves. They have sandy coves and rocky landforms (CASS). They are usually eroding faster than depositioning

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3
Q

What is a low energy coast and what are its features?

A

Has small, gentle waves. Sometimes have a reef, and saltmarshes/ tidal mudflats. Are often deposition landscapes

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4
Q

What is the difference between a constructive and destructive wave?

A
  1. Constructve has low frequency (6-8 waves a minute) whereas destructive is 10-14 a minute
  2. Constructive waves are low and long and have an ellipticcal cross profile, whereas destructive waves are high and steep and have a circular cross profile
  3. Constructive has powerful swash which deposits material, and weak backwash, whereas destructive has a weak swash and a strong backwash which erodes material
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5
Q

What are the 5 inputs of sediment into the coastal system?

A
  1. Rivers
  2. Sea level rise (floods valleys)
  3. Erosion (from cliffs)
  4. Crushed shells of marine organisms
  5. Offshore deposits (through waves and tides
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6
Q

What is a sediment budget?

A

The difference between the rate of erosion and the rate of deposition

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7
Q

What are the six erosion processes?

A
  1. Abrasion (when rocks in the water smash against the cliff)
  2. Hydraulic Action (when air in cracks is compressed when waves crash against the cliff
  3. Cavitation (as waves recede, air inside the cliffs expands violently, putting pressure on the rock
  4. Wave quarrying (the energy of the wave hitting the rock can cause cracks
  5. Solution (soluble rocks get dissolved by seawater
  6. Attrition (bits of rock in the water smash against each other and break into smaller pieces)
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8
Q

What are the four transportation processes?

A
  1. Solution (when substances dissolved in the water are carried along)
  2. Saltation (larger particles bounce along the sea bed
  3. Suspension (very fine material is suspended in the water and carried along)
  4. Traction (very large particles are pushed along the sea bed
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9
Q

What is the difference between marine deposition and aeolian deposition?

A

Marine deposition is done by sea water whereas aeolian deposition is done by wind

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10
Q

What are the five types of mass movement?

A
  1. Landsllides (when soft rock collapses due to heavy rainfall)
  2. Rock falls (occur in cliffs undercut by the sea or on slopes affected by mechanical weathering
  3. Mudflows (heavy rain causes soil to become saturated and for it to slip)
  4. Rotational slip (where soft material lies on top of resistant material, meaning that water will form a liquid layer between these and cause the softer rock to slide laterally)
  5. Soil Creep (very slow, almost iperceptible movement of soil
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11
Q

How are wave-cut platforms created? (erosional process)

A
  1. A notch is formed in the cliff at the high tide mark
  2. A cave is formed by repeated erosion
  3. The rock above the cave collapses and the cliff retreats
  4. this process repeats, creating a wave-cut platform as the cliff retreats
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12
Q

How are headlands and bays formed? (erosional process)

A
  1. In a discordant coastline, there are layers of hard and soft rock perpendicular to the coast
  2. the soft rock is eroded quickly, meaning it retreats more than the hard rock
  3. This means that the bays are more sheltered by the headlands, leading deposition to occur in the bays as beaches
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13
Q

How are CASS formed? (erosional process)

A
  1. There is a crack in the headland
  2. This crack is expanded by erosion and a small cave eventually forms
  3. The cave is then knocked through the other side of the headland, creating an arch
  4. The ‘bridge’ on top of the arch collapses, leaving a stack
  5. the stack collapses, leaving a stump
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14
Q

How are beaches formed? (depositional process)

A
  1. Constructive waves deposit sediment

2. Berms are formed at the high tide mark, formed of sand and pebbles

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15
Q

How are spits formed? (depositional process)

A
  1. Longshore drift deposits material across the river mouth
  2. Occasional changes to the dominant wind may mean that the spit has a recurved end
  3. Over time, several recurved end smay be abandoned as the spit continues to grow as the waves change direction
  4. Area behind the spit is sheltered and often develops mudflats and saltmarshes
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16
Q

How are offshore bars and tombolos formed? (depositional process)

A
  1. Bars are formed when a spit joins two headlands together (either in a bay or across a river mouth
  2. A lagoon forms behind the bar
  3. If a bar is partially submerged by the sea, it is called an offshore bar
  4. A bar that connects to an island is called a tombolo`
17
Q

How are barrier islands formed?

A
  1. Barrier islands were probably formed during the last ice age
  2. They form parallel to the coast where there is a good supply of sediment, a gentle slope, fairly powerful waves and a small tidal range
  3. they are long, narrow islands of sand or gravel
  4. a lagoon or marsh often forms behind the barrier island
18
Q

How are sand dunes formed? (depositional process)

A
  1. Sand is deposited and moved up the beach by wind
  2. Sand trapped by driftwood or berms is colonised by plants and grasses, forming embryo dunes
  3. They continue to grow until they become mature dunes, which are colonised by different species over time as the soil changes in the sand dune to due decomposition
19
Q

How are mudflats and saltmarshes formed? (depositional process)

A
  1. Form in sheltered, low energy environments
  2. As silt and mud are deposited by the river, mudflats develop
  3. The mudflats are colonised by vegetation that can survive the high salt levels and submergence
  4. The plants trap more mud and silt, building up the marsh until areas remain exposed for longer and longer
  5. Complex creek systems form and drain the marsh
  6. This leads hollows to fill with saltwater which evaporates, leaving a layer of soil too high in salinity for plants to grow, which is called the salt pan

Case studies: Coastal systems (16 decks)

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