Coasts Flashcards
What is long shore drift
Process of transportation which moves sand and pebbles along the coast as waves approach the coast at and angle
What does swash do in long shore drift
The Swash carries sand and pebbles up the beach
backwash draws the sediment backdown at right angles.
Causing a zig zag movemeny
How is a spit formed?
Material is transported by the coast due to long shore drift and is deposited on the seabed.
Gradually more and more sediment is deposited forming a ridge that extends out to see.
open water, fresh water and sea water are trapped behind the ridge.
As the ridge extends deeper to open waters, the wind and waves approaching from different directions.
Causing the spit to curve.
A spit will not form completely across the gap in the coastlines due to strong river and sea currents
What is a bar?
A bar is a ridge of sand across the entrance to a bay or river mouths.
How is a beach formed?
When eroded material is transported by long shore drift and deposited by constructive waves.
How is a bar formed?
Material is deposited along the coast by long shore drift and deposited where there is a bend on the coastline.
Deposition continues in a line right across the entrance to the bay or river mouth.
What is a spit?
A long narrow ridge of sand, one end of which is attached to land, while towards the other end has a gap
How is climate change causing issue for coastal landscapes?
Rising sea level can lead to cliffs that are currently benign undercut and collapsing will continue to retreat.
Areas of soft coastline may experience more erosion.
———————————-//————//—STORM SURGES - a large scale increase in sea level due to a storm
What is soft engineering?
Flood defences that work with natural processes to reduce the impact of coastal or river flooding
What is hard engineering?
Flood defences made by humans
What are the advantages of a sea wall?
Protects the base of cliff
Made of resistant concrete
Reflects energy if recurved
What are the disadvantages of a Sea wall?
Expensive
Unsightly
What is a groyne
A wooden barrier built at right angles, to break waves and reduce the movement of sediment along the coast.
What are the benefits of Groynes?
Builds a wide beach
Beach attracts tourists
What are the disadvantages of a Groyne?
High maintenance - Wood Rots
Sand prevented from moving so can cause erosion further along the coast
What is beach replenishment?
Adding sand to increase the width of the beach
What are the benefits of beach replenishment.
Cheap
Looks natural
Attracts tourists
What are the disadvantages of beach replenishment.
Material transported easily.
Replacement of sediment is needed regularly.
What is Slope stabilisation?
Slope stabilisation is a technique where drains are installed at the top of the cliff preventing rocks becoming saturated.
What are the benefits of slope stabilisation?
Prevents mass movement
Keeps cliff in place
Safer for people on beach
What is the disadvantages of slope stabilisation?
Difficult to install
Costly
How are destructive waves formed?
Formed by strong winds that have blown over long fetches.
How are constructive waves formed and what do they do?
Associated with light winds and short fetches.
Less energy and smaller than destructive waves encouraging Deposition.
What is a discordant coast
A coast where bands of hard rock and soft rock lie at right angle to the coastline forming headlands and bays
What is a concordance coast
The type of coast where rock types run parallel to the coast line
What is attrition?
Occurs when pieces of rock are moved by waves and knock into each other.
What is Abrasion?
When waves pick up sand and pebbles and throw and scrape them against the rock surface.
What is Hydraulic action?
When large waves break against a cliff compressing air into cracks
What is solution?
Occurs when sea water dissolves minerals causing disintegration of rock.
How is a wave cut platform formed?
Hydraulic action and abrasion, the waves undercut the cliff
Creating a wave cut notch, as it gets deeper the cliff ONTOP eventually collapses.
Repeating of this eventually caused retreat of the land.
A gently sloping rocky area is left at the bottom called a wave cut platform
