Coast Flashcards
What is “marine erosion”?
Wearing away of cliffs by waves
Corrasion/Abrasion
Large waves hurl beach material
Corrosion/solution
Salts + acids slowly dissolve
Attrition
Waves
stones collide + disintegrate
Hydraulic Action
Force of waves compresses air in the cliffs
Constructive waves
Low height
Gentle beach gradient
Swash > backswash
–> Deposit material + build up beaches
Destructive waves
High height
Steep beach gradient
Backswash > Swash
–> Erosion (beach material is pulled down the beach)
Longshore drift processes
- Oblique onshore winds drive wave crest at an angle to shore
- Swash carries materials up beach at an oblique angle
- Backswash brings materials straight down
- Gradually move materials along beach in zig-zag motion.
Explain why some coastlines have headlands and bays
Alternate bands of hard and soft rock along coasts
hard rock resists erosion
forming headlands
soft rock easily eroded
forming bays
differential erosion (?)
Explain how different erosional processes shape cliffs + wave-cut platform
Hydraulic action/ corrasion/ corrosion/ where is attrition (explain)
undercutting
Rock above collapse
as cliff cannot take weight of overhanging section
Wave-cut platform where cliff once stood
Conditions needed for formation of sand dunes
on a sand spit onshore winds supply of sand obstruction for sand to build up around marram grass to hold them together
How a sand spits is formed
MORE
Content Guide: Answers are likely to refer to; Prevailing wind, Longshore drift, Deposition, Change of direction of coastline etc.
How a natural arch is formed
erosion ( hydraulic action/corrosion); description of process enlarges joints on resistant rock formation of cave cave breaks through headland to form arch
Explain how erosion by the sea may cause problems for people living in coastal area
Ideas such as: • danger to properties on cliff top; • people may need to evacuate; • loss of farmland/loss of gardens; • reduction in food production; • roads may be damaged; • collapse of cliffs may make beaches dangerous/rock falls can kill people; • less tourists come; • cost of protection measures; • can’t get insurance for properties/unable to sell properties; etc.
