Coasts Flashcards
What is chemical weathering?
Rocks reacting with slightly acidic water e.g. limestone dissolved by carbonation.
What is biological weathering?
Action of plants and animals, causing rock to split apart.
What is mechanical weathering?
Water falls into cracks in rocks and freezes, causing it to expand over time the repeated thawing and freezing causes the rock to break apart.
How does mass movement work on the coast?
Mass movement is downhill movement of material under influence of gravity.
What are the types of mass movement vary according to?
Material involved, amount of water in material, type of movement e.g. sliding.
What is abrasion?
Breaking waves throw sand, pebbles and boulders against coast during storms.
What is hydraulic action?
Sheer weight and impact of water against coastline, particulary during storm, erodes coast. Also waves compress air in joints in rocks, forcing them apart.
What is solution?
Chemical action of seawater dissolves some rocks.
What is longshore drift?
Process by which beach sediment can be transpoted along coast by waves.(see revisin guide).
How does longshore dirft transport material along the coastline?
Directin of material movement determined by prevaling wind direction. Waves approach coastline at acute angle, bringing sediment onto beach in swash. sediment then dragged back to sea in backswash, under force of gravity at a right angle. Process continues in zigzag pattern, moving sediment along beach.
What is traction?
Latge boulders are rolled along seabed by waves.
What is saltation?
Smaller stones are bounced along seabed.
What is suspension?
Sand and small particles are carried along in the flow.
What is solution?
Some minerals are dissolved in seawater and carried along in the flow.
What is deposition?
Load carried by waves is deposited by constructive waves.
What are the different factors that influence dieposition?
Sheltered spots e.g. bays. Calm conditions. Gentle gradient offshore causing friction. All reduce wave’s energy.
What is geological structure?
Geology affects how fast coastal erosion occurs. Soft rock is eroded much faster than hard rock. Particular landforms are created when soft rocks and hard rocks occur together.
How does soft rock influence a coastline?
Easily eroded by sea. Cliffs will be less rugged and less steep than hard rock coasts. Soft rock landscapes include bays.
How does hard rock affect the coastline?
Resistant to all types of erosion. Cliffs will be high, steep and rugged. Hard rock landscapes include wave-cut platforms and headlands where caves, arches and stacks are formed.