(B) Coastal Landscapes Flashcards by edward waller

What is marine erosion

The removal of material be waves

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3 types of marine erosion

Hydraulic action
Abrasion/corrasion
Attrition
Solution

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What is hydraulic action

The force of waves against rocks

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What is abrasion/corrasion

The force of material against rocks

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What is attrition

The force of load particles colliding with each other

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Examples of when rate of erosion is higher

Coastline exposed to large fetch
Jutting headland
Softness of rocks

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Characteristics of constructive waves

Height - Under 1m
Shape - long
Swash- strong
Backwash - weak
Number per min - 8-10
Effect on beach - build it up
Typical season - summer

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Characteristics of destructive waves

Height - over 1m
Shape - short
Swash- weak
Backwash - strong
Number per minute - 10-14
Effect on beach - drags material away
Typical season - winter

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Headland definition

Cliff that just out to sea surrounded by water on 3 sides

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Bay definition

Crescent shaped indentation in the coastline between 2 headlands

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Where do bays and headlands form

Where there are alternate bands of resistant and less resistant rock

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Types of erosion to create bays and headlands

Hydraulic action

Abrasion/ corrasion

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Cliff definition

A steep or vertical face of rock often found at a coast

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Wave cut platform definition

A wide gently sloping rocky surface at the foot of a cliff

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How are waves cut platforms formed

Destructive waves hit the cliff face to cause undercutting as a result of corrasion and hydraulic action
This cause a wave cut notch and so the cliff falls
As the cliff retreats a wave cut platform is left

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Recall caves, arches, and stacks

Cracks appear In headland
Becomes eroded and breaks to form a cave
Continues to erode to form an arch
Arch collapses and leaves a stack
Breaks and causes a stump

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Beach definition

A landform of coastal deposition that lies between the high and low tide levels

Sandy beach characteristics

Gradient: Almost flat
Dominant wave: Constructive
Distance stretch inland: Long
Back of beach: Sand dunes
Other: Runnels form at low tide

Pebble beach characteristics

Gradient: Steep
Wave type: Destructive
Distance stretch inland: Short
Beach of beach: Storm beach (large pebbles)
Other: Pebbles increase in size further back

What is a berm and where are they mainly found

A terrace on a beach formed when sand/shingle is slowly moved up a beach by successive incoming tides.
Found at the back of shingly beaches

What are runnels and where are they found

Channels that allow drainage when tides are low

On a sandy beach

What are sand dunes

Large heaps of sand, form on dry backshore of sandy beaches

What do sand dunes need to form

large flat beach
supply of sand
large tidal range so there is time for sand to dry
on shore wind
obstacle for dune to form against

Describe formation of sand dunes

sand continues to move up the windward slope
height builds until structure is unstable
sand then slips down the leeward side

Characteristics of sand dunes

- gentle slope on windward side - crests - unstable steep slope on leeward side

6 types of dune in order

``` Embryo dune Fire dune Yellow dune Grey dune Dune slack Mature dune ```

What is dune slack

Where there is a trough or low point in a line of dunes

What is a leeward slope

Slope facing away from wind

What is windward slope

The slope facing the wind

3 processes in which sand moves

Suspension Saltation Creep

What is suspension

Sand is picked up and carried by wind (1%)

What is saltation

Sand bounces along as the wind picks it up and drops it (95%)

What is creep

Sand collides with each other and push other grains along | 4%

3 ways load is transported on to a beach

Traction Suspension Saltation

How is load transported along a beach

Long shore drift

What determines the direction of longshore drift

The prevailing wind

When does deposition mainly occur

``` Low energy waves Sheltered bays Constructive waves Flat beach Large source of sediment Engineered structures trap sediment ```

What is a spit

An area of sand or shingle which extends at a gentle angle out to sea or which grows across a rice estuary. May have a hooked or curved end

Requirements for spit to form

- longshore drift - sudden change in direction of coastline - relatively shallow sea - possible more sheltered sea

Formation of a spit

Material is carried via longshore drift A change in the direction of the coastline causes a sheltered area to form Shallow water means that it loses energy and deposits material Prevailing wind causes spit to curve inward forming a hook Salted marshland forms behind the spit