Rivers & Coasts - Coasts Flashcards
What are the types of coastal weathering/erosion?
Mechanical weathering Chemical weathering Hydraulic action Corrasion Attrition Corrosion
What is mechanical weathering?
Water gets into cracks in rock, when the water freezes it expands and puts pressure on the rock, when it thaws it contracts and releases the pressure. Repetition of this causes the cracks to widen and break apart
What is chemical weathering?
Rainwater has CO2 dissolved in it, which makes a weak carbonic acid, this acid reacts with the rock and dissloves it
What is hyrdraulic action?
Waves crash against the rock and compresses the air inside its cracks, this puts pressure on the rock and the repeated compression causes the rock to break apart
What is corrasion?
Eroded particles in the water scrape against the rock which removes small pieces at a time
What is attrition?
Eroded particles in the water smash against each other and break into smaller fragments, their edges also get rounded off
What is Corrosion?
Weak carbonic acid in seawater dissolves rocks like chalk and limestone
What is a destructive wave?
They have high frequency
They are high and steep
Their backwash is more powerful than swash
The 2 main factors that affect their size and power are wind and fetch (the distance the water has blown to produce a wave)
What is the order of coastal landforms?
Cracks - cave - arch - stack - stump
How do headlands and bays form?
Where there is alternating bands of hard and soft rock
How do coves form?
Where there are parallel bands of hard and soft rock
What is transportation?
The movement of material - waves follow the direction of the prevailing wind, they hit the beach at a non 90 degree angle, the swash carries the material up the beach, the backwash brings the material back down the beach at 90 degree angles, over time material zigzags across the beach
What is traction?
Where large particles like boulders are pushed along the sea bed by water
What is suspension?
Small particles like silt and clay are carried along in the water
What is saltation?
Pebble sized particles bounce along the sea bed by water