The Coastal Zone Flashcards
What is weathering?
The disintegration/decay of rocks in their original place; at or close to the ground’s surface
What are the three different types of weathering?
Mechanical, Chemical and Biological
What is freeze-thaw weathering?
During rainfall, water seeps into pores/cracks in the rock, overnight- temperature drops, water expands as it freezes, cracks widen, over time rock disintegrates
What is mass movement?
Downhill movement of material under the influence of gravity. (material can slide or slump)
What is rockfall?
Rapid fall of rock fragments from cliffs of 40 degrees or steeper - often due to freeze-thaw
What is a landslide?
Blocks of rock slide downhill; chunks of land may stay intact
What is mudflow?
Saturated soil and weak rock flows down a slope
What is rotational slip?
A slump of saturated soil and weak rock along a curved surface
What is exfoliation?
The outer ‘skin’ of rock flakes away due to constant expansion and contraction of the outer layer as the temperature changes- causing it to flake away
What is solution (weathering)?
The dissolving of minerals in the rock by rainwater
What is carbonation (weathering)?
Rainwater picks up carbon from the air, so it becomes a weak carbonic acid. Acid reacts with calcium carbonate (chalk and limestone) to form calcium calcium bicarbonate- which then dissolves
What are the main source of erosion along the coastline?
Waves
What is the fetch?
The stretch of water which the wind blows over
What does a long fetch cause?
Larger waves
What are the characteristics of constructive waves?
Strong swash, weak backwash, so create long slightly sloping beaches
What are the characteristics of destructive waves?
Weak swash, strong backwash, so erode beaches to become short and steep
What is hydraulic action?
The sheer force of the waves forcing air into the cracks in the rock
What is attrition?
Rocks smash together, eroding each-other to become smaller and smoother
What is abrasion/corrasion?
Pebbles/rocks hit against cliffs, which erodes cliffs- and pebbles- (like sandpaper)
What is solution (erosion)?
Rocks are dissolved by a chemical reaction with the sea water
What are the rock layers called?
The rock strata
What is a discordant coastline?
Bands of soft and hard rock are perpendicular to the sea
What is a concordant coastline?
Bands of soft and hard rock are parallel to the sea
What type of coastline forms headlands and bays?
A discordant coastline
Which type of rock forms a bay?
Soft rock
Which type of rock forms a headland?
Hard rock
What is wave refraction?
The bending of the waves around an obstacle, e.g. a headland
Once headlands and bays have formed, where is erosion most concentrated?
On the headlands
What types of erosion cause wave-cut platforms?
Hydraulic power and abrasion
Where is the erosion concentrated on in the formation of a wave-cut platform?
Between the high water mark and the low water mark (the inter-tidal zone)
What is formed in the inter-tidal zone?
A wave cut notch, with an overhang above it
How can the formation of wave-cut platforms be summed up?
Overhang, collapse, repeats, retreats
What land-forms of erosion can be found on a headland?
Crack, cave, arch, stack, stump
What is solution (transportation)?
Minerals are dissolved in the seawater and carried in solution, so the load is invisible
What is suspension?
Small particles are carried in the water; water appears clouded
What is saltation?
Load is bounced along the sea bed, as the current cannot keep it afloat for long periods of time
What is traction?
The largest sediment in the load is rolled along the seabed; it is too heavy for the current to carry
What is longshore drift?
When material can be seen moving along the beach/coast (in the direction of the prevailing wind at that time)
What is deposition?
The build-up of material dropped by the sea
When does deposition occur?
When: the coast is sheltered (small waves); waves are constructive; waves have too much material; there is an obstacle (groyne, shipwreck)
What are ridges/berms?
Small ridges on a beach, which coincide with high-tide lines and storm tides
Where are pebble beaches commonly found?
Where cliffs are being eroded, and where there are high energy waves