3.5 Marine Processes Flashcards
What are the 5 coastal erosion processes?
- hydraulic action
- wave quarrying
- corrasion
- abrasion
- solution (corrosion)
Outline the coastal erosion process: hydraulic action.
Hydraulic action is the sheer force of the water as it crashes against a coastline.
When a wave advances, air can be trapped and compressed, either in joins in the rock or between the breaking wave and the cliff. When the wave retreats, the compressed air expands. This continuous processes can weaken cracks in the cliff, causing pieces to break off.
Simultaneously, bubbles forms dim the water may implode under the high pressure - generating tiny jets of water which will over time erode the rock. (Aka cavitation).
Outline the coastal erosion process: wave quarrying.
Wave quarrying is the action of waves breaking against unconsolidated material eg sand and gravel.
Outline the Marin erosion process: corrasion.
When waves advance, they pick up sand and pebbles from the sea bed. When they break at the base of the cliff, the transported material is hurled off the cliff, chipping away at the rock.
The size, shape and amount of sediment picked up by the waves, along with type of wave, determines the relative importance of the erosion process.
Outline the marine erosion process: abrasion.
In abrasion, sediment is dragged up and down or across the shoreline, eroding and smoothing rocky surfaces.
Outline the marine erosion process: solution.
Weak acids in sea water can dissolve alkaline rocks (eg chalk).
What is attrition?
The gradual wearing down of rock particles by umlaut and abrasion, as the pieces of rock are moved by waves, tides and currents. This process gradually makes stones rounder and smoother.
Name factors that affect coastal erosion.
Waves Rock type Presence of absence of a beach Costal management Subaerial processes Geological structure
Outline how waves affect coastal erosion.
The area and type of erosion experienced is influenced by the size and type of waves that reach the coast.
Most erosion happens surging winter storms, when destructive waves are their largest and most powerful.
Outline how rock type affects coastal erosion.
Rock lithology (its physical strength and chemistry) is important in determining the rate of erosion.
Tough and resistant ricks eg granite erode at v slow rates compared to weaker clay and shales. Eg at the Holderness coast, unconsolidated glacial till deposits have been eroded by 120m in past century.
Outline how the presence / absence of a beach affects coastal erosion.
Beaches absorb wave energy and reduce the impact of waves on a cliff.
If a beach is absent, following excessive erosion, a cliff may experience increase erosion as it’s more vulnerable to wave attack.
Outline how coastal management affects coastal erosion.
The presence of structure eg groynes have an impact on sediment transfer and patterns of wave energy along a coastline. In trapping sediment moved by longshore drift, groynes may deprive beaches further down drift of sediment and may decrease in extent.
Name the 4 coastal transportation processes.
Traction, saltation, suspension, solution.
Outline saltation.
Sediment bounced along sea bed. Light enough to be picked up but too heavy to remain in flow of water.
What are the key factors affecting the type of transportation?
Velocity (energy) and particle size (mass)
