4.3, 4.4, 4.5 Flashcards
How are spits formed
Longshore drift brings sediment eroded from rock nearby along the shore and resides against a rocky feature, building on itself as more sediment is deposited beside it.
Why do some coastlines have beaches and headlands
Different layers of rock along a discordant rock line.
How is sediment transported
Suspension, bouncing along the seabed, and saltation.
What is a concordant coastline
A coastline where the different types of rock run at a 90 degree angle to the ocean and erode at different rates allowing for beaches and headlands to form.
What is a concordant coastline?
A coastline which only has one layer of rock exposed to the ocean which means cliffs are usually formed in these cosatlines.
How ar bays formed?
When a concordant coastline has a thin layer of soft rock exposed, it erodes deeper into it until a bay is formed, leaving outer hard rock around itself.
Main difference between a discordant and concordant coastlines
A concordant headland has cliffs and bays whilst a discordant coastline has usually headlands and beaches
How can humans stop longshore drift
Groynes
How do groynes prevent longshore drift?
They stop the sediment travelling across the beach by trapping it at a point, where the groin is.
Why do we want to stop longshore drift in some cases?
When certain natural features like beaches are wanted to be preserved, groynes are used to stop longshore drift and all the sand moving elsewhere via longshore drift.
Indirect human effects on natural landscapes
Housing
Use of ports and harbours constantly widening the mouth if the ports
Large buildings and renovation.
Different ways of erosion
Abrasion, hydraulic action, freeze thaw weathering.
What wave has a stronger swash than backwash and what does this cause?
Constructive wave, this deposits sediment more then it takes sediment from the beach.
What wave takes sediment from the beach and backwash is more powerful than its swash?
Destructive wave
How is a arch formed?
- headland has a fault
- fault erodes through freeze thaw, hydraulic action or abrasion.
- erosion causes the fault to increase in size.
- once the base has been eroded enough, the rock above isnt supported so it crumbles leaving a arch.