Coastal process Flashcards
The factors the size and energy of a wave depends on
The fetch
The strength of wind
How long the wind has been blowing for
What is the fetch?
How far the wave has travelled
What are the 2 types of waves?
Constructive and destructive
What is the swash?
The movement of water up the beach
What is the backwash?
The movement of water up the beach
Properties of a destructive wave
High wave in proportion to length
Tall breaker; breaks downward ms with great force
Strong backwash
Weak swash
strong backwash removes sediment off beach
Waves are steep and close together
Characteristics of a constructive waves
Strong swash and weak backwash
Strong swash bring sediments to build up the beach
Backwash is not strong enough to remove sediment
Waves are low and further apart
What are the 3 types of weathering?
Mechanical
Biological
Chemical
Mechanical weathering
Freeze-thaw
Occurs when rocks are porous or permeable
1. Water enters crack
2. When temperature drops, water freezes, crack widens
3.Ice melts and water gets deep
4. Freezes and expands, repeats till rock splits
Biological weathering
Plant and animal
roots get into small cracks, as they grow, cracks grow
Rock breaks off
Chemical weathering
Rain and sea water can be weak acid
Dissolved soft rock like limestone or chalk
4 types of mass movement
Rockfall
Mudflow
Landslide
Rotational slip
Define rockfall
bits of rock fall off the cliff face, usually due to freeze thaw
Define mudflow
Saturated soil flows down a slope
Define landslide
large blocks of rock slide downhill
Define rotational slip
Saturated soil slumps down curved surface
4 types of erosion
Hydraulic action
Abrasion
Attrition
Solution
Define Hydraulic action
sheer power of waves as they smash against cliff. Air becomes trapped in cracks in rock and cause rock to break
Define abrasion
pebbles grind along rock platform like sandpaper, rock becomes smooth
Define attrition
when rocks in sea knock against eachother , become smaller and rounded
Define solution
when sea water dissolved certain types of rocks, Uk- chalk and limestone
Define erosion and what waves are responsible for it
Wearing away do rocks
Destructive waves
4 types of transportation
Solution
Suspension
Saltation
Traction
Define solution
when minerals like limestone and chalk are dissolved in sea water and then carried in solution. Not visible
Define suspension
Small particles such as silts and clays are suspended in flow of water
Define saltation
small pieces of shingle or large sand grains are bounced along sea bed
Define traction
Where pebbles and larger material are rolled along sea bed
Define longshore drift
waves approach coast an an angle because of the direction of prevailing wind. Swash will carry material towards beach at an angle. Backwash then flows back to the sea, down the slope of the beach. Zigzag
Define deposition
When sea loses energy, drops material is has been carrying.
Constructive waves
Factors leading to deposition
Waves starting to slow down and lose energy
Shallow water
Sheltered areas, eg bays
Little or no wind