(B) Coastal Landscapes Flashcards
What is marine erosion
The removal of material be waves
3 types of marine erosion
Hydraulic action
Abrasion/corrasion
Attrition
Solution
What is hydraulic action
The force of waves against rocks
What is abrasion/corrasion
The force of material against rocks
What is attrition
The force of load particles colliding with each other
Examples of when rate of erosion is higher
Coastline exposed to large fetch
Jutting headland
Softness of rocks
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
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
Headland definition
Cliff that just out to sea surrounded by water on 3 sides
Bay definition
Crescent shaped indentation in the coastline between 2 headlands
Where do bays and headlands form
Where there are alternate bands of resistant and less resistant rock
Types of erosion to create bays and headlands
Hydraulic action
Abrasion/ corrasion
Cliff definition
A steep or vertical face of rock often found at a coast
Wave cut platform definition
A wide gently sloping rocky surface at the foot of a cliff
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
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
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
