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Undeleted > Coastal Processes > Flashcards

Coastal Processes Flashcards

1
Q

How is the Littoral Zone Structured?

A

Coast-Backshore-Foreshore-Nearshore-Offshore

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2
Q

What are the types of coast?

A

Rocky coast, Coastal plains, Cliffed coast, Sandy coastline and Estuarine coastlines.

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3
Q

What do Rocky Coastlines have?

A

Cliffs varying in size and lithology.

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4
Q

What do Coastal plains have?

A

Land that slowly slopes towards the sea across deposited sediment.

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5
Q

What do Cliffed Coasts have?

A

Abrupt land to sea transition. The foreshore zone is exposed as a rocky platform.

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6
Q

What do Sandy coastlines have?

A

Dune vegetation that stabalises them.

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7
Q

What do Estuarine coastlines do?

A

They gradually transition from land to sea and form salt marshes.

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8
Q

What is a cliff profile?

A

The height, angle and features of a cliff face.

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9
Q

What are features of a marine erosion dominated cliff profile?

A

Steep face, active undercutting, limited cliff base debris.

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10
Q

What are features of sub ariel processes dominated cliff profiles?

A

Curved slope profile, lower angle face, accumulated debris.

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11
Q

What three things determine erosion resistance?

A
  1. How reactive rock minerals are when exposed to chemical weathering.
  2. Whether rocks are clastic (sedimentary) or crystalline (igneous and metamorphic)
  3. The degree of cracks, fractures and fissures in the rocks as thses are exploited during weathering and erosion.
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12
Q

Why are coastal plains poorly drained?

A

They are just above sea level.

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13
Q

In what two ways are coastal plains formed?

A
  1. Fall in sea level exposing sea bed.
  2. Deposition of sediment from the land brought to coast by river systems.
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14
Q

What is coastal accretion?

A

The deposition of sediment at the coast, and the seaward growth of the coastline creating new land.

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15
Q

What is Dynamic equalibrium?

A

Balanced forces of, deposition from external sources e.g. river systems. And erosion by marine action at the coast.

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16
Q

What is the strata?

A

Different layers of rock within an area and how they relate to each other.

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17
Q

What is deformation?

A

The degree to which rock units have been tilted or folded due to tectonic activity.

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18
Q

What is Faulting?

A

Major fractures that have moved rocks from their original positions.

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19
Q

What defines Concordant coasts?

A

They are generated when rock strata runs parralel to the coastline.

20
Q

What defines Discordant coasts?

A

Different rock strata intersects coast at an angle. This varies the Geology.

21
Q

How do discordant coastlines erode over time?

A

As they are dominated by headlands and bays.

  • Less resistant rocks form bays.
  • More resistant rocks remain as headland
  • Especially resistant areas remain as detached islands.
22
Q

How do wave crests behave on divergent coastlines?

A

Headlands are eventaully eroded enough to meet bays due to wave crests.

In smooth areas wave energy diverges, hitting the whole area so eroding weak rock more creating bays.

In headland areas wave energy converges so its all focused on headlands increasing erosion there. So eventually they smooth over by meeting bays.

23
Q

Give an example of a Concordant coastline.

A

Lulworth Coast Dorset. Strata run parallel but vary in terms of resistance.

Offshore portland limestone protects softer rock landwards.

At Lulworth cave marine erosion has penetrated the resistance layer and rapidly eroded caves behind.

But back of cave is resistant chalk stopping nay further erosion inland.

24
Q

Give an example of a Concordant coastline that forms lagoons.

A

Haff coastlines, found on southern fringes of the baltic sea. Long sediment ridges topped with sand dunes run parallel to coast just offshore creating lagoons between ridges and shores.

25
Q

What two factors effect cliff profiles?

A

Resistance to erosion of rock.

Dip of rock strata in relation to coastline.

26
Q

What is the dip?

A

Angle of rock strata in relationship to horizontal. Effected by tectonic processes.

27
Q

How do certian dips relate to erosion rates?

A

Horizontal dip: Weak strata, more easily eroded

Seaward dip, high angle: One rock layer facing the sea vulnerable to rock slides and varying ersoion levels.

Seaward dip, low angle: Exceeds 90° producing areas of overhanging rock vulnerable to rock falls.

Landward dip: Steep profiles 70°-80° with stable cliff and few rock falls.

28
Q

What are Faults?

A

Weaknesses within rock layers.

29
Q

What are joints?

A

Divisions in rock strata causing it to form blocks of a regular shape.

30
Q

What are fissures?

A

Very small cracks in rocks that can be exploited by erosion.

31
Q

What do Joints, Fissures and Faults determine?

A

Where caves and cut notches are in the cliff.

32
Q

How are Anticlines and Synclines formed?

A

As a result of sedimentary rock being folded by tectonic forces. This crustal compression squeezes the horizontal strata creating anticlines and synclines.

33
Q

What is the Lithology and erosional resistance of Igneous rock?

And give examples.

A

Few joints, interlocking crystals, very resistant.

Granite, Basalt.

34
Q

What is the Lithology and erosional resistance of Metamorphic rock?

And give examples.

A

Can have interlocking crystals, can have crystals all facing one direction making it weak, often heavily fractured. But can be resistant.

Slate, Schist

35
Q

What is the Lithology and erosional resistance of Sedimentary rock?

And give examples.

A

Clastic, often young, many fractures. Quite weak.

Sandstone, Limestone

36
Q

Whats another feature that effects rock’s erosional resistance?

A

Permeability.

Permeable rocks tend to be more weak to erosion as it removes the cement binding rocks together.

It can also create high water pore pressure risking surface run off erosion on cliffs.

37
Q

What does coastal vegetation protect?

A

Coastal sand dunes, salt marshes, and mangrove swamps.

38
Q

How does vegetation stabalise sediment?

A

Roots of plant bind sediment together becoming a protective layer to sediment from water.

It also reduces wind speed so surface friction.

39
Q

What does coastal vegetation mostly consist of? And why?

A

Halophytes- As they tolerate salt water.

Xerophytes- As they tolerate dry conditions.

40
Q

What’s the term for a sand dune ecosystem?

A

Psammosere

41
Q

What’s the term for a salt marsh ecosystem?

A

Halosere.

42
Q

How do Pioneer plants alter Coastal dunes to better suit other plants?

A
  1. They start colonising the area.
  2. They stabalise sand, reduce wind speed an begin soil formation by leaving organic matter.
  3. This alters the conditions allowing other plants to grow.
43
Q

What areas can wind erosion create?

A

Low areas called dune stacks.

44
Q

What dunes are prone to wind and wave erosion?

A

Embryo and Fore dunes.

45
Q

How is Marramm grass specifically designed to keep Coastal dunes in place?

A

They have flexible waxy leaves and long roots.

46
Q

How do Estuaries create salt marshes?

A
  • Being sheltered from strong waves so sediment can be deposited.
  • Sediment in river mouth can add to sediment at Estuary.
  • This helps create Salt marshes.

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