Geography Marine processes 10.3
- Created by: jodie.g
- Created on: 23-05-18 19:09
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- Marine processes
- Coastal erosion
- Hydraulic action
- Destructive waves pound base of cliffs
- causes repeated changes in air pressure as water is forced in and out of joints
- Forward surge of water compresses air in he cracks and, as the wave retreats, there is an explosive effect
- Abrasion
- Destructive waves hurl sand and shingle at cliffs
- the scratching and scraping of the rock surface is called abrasion
- Attrition
- Grinding down of load particles
- pebbles collide during transport
- wears away jagged edges to make rounded pebbles
- Corrosion
- dissolving of rocks such as chalk and limestone
- Hydraulic action
- Rate of erosion affected by...
- Larger fetch-higher rate
- Stronger wind-destructive waves-higher rate
- No beach between the sea and cliffs-higher rate
- headland juts out to sea-waves gain height-wave refraction-higher rate
- Softer rocks-higher rate
- Rock has more joints-higher rate
- Material transported by waves
- Transport onto beach
- Larger and heavier the load, greater velocity needed for transport
- Load is transported by waves
- Lightest load is carried by suspension or saltated
- Heavier load moved by traction
- Transport along beach parallel to shore
- Transported by longshore drift
- Direction determined by prevailing wind
- Swash surges up beach and backwash goes back down at right angle to the shore
- Transport onto beach
- Conditions causing deposition
- Low energy sheltered bays where constructive waves are dominant
- Large source of sediment updrift
- Large expanses of flat beach so swash spread out over large area
- Tidal material is trapped behind a spit
- Engineered structures like groynes trap sediment on the updrift side
- Coastal erosion
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