Distinctive Landscapes 2 Flashcards
(22 cards)
What is Swash and Backwash?
Swash: The movement of water that is carrying material up a beach.
Backwash: The movement of water down a beach, eroding and transporting material into the sea.
How are Headlands and Bays formed?
• Headlands form on coasts where hard, more resistant rocks are slowly eroded
• Bays are formed in between Headlands, where soft less resistant rocks easily erode
Example: Marloes Peninsula, Wales
What are the Landforms created through Headland erosion?
Cave -> Arch -> Stack -> Stump
What are Constructive and Destructive Waves?
Constructive: Waves smaller in height + energy with a strong swash.
Destructive: Waves larger in height and energy with a strong backwash.
Define Mass Movement
The movement of material/sediment down a slope due to gravity. This can be rapid (eg. Mudflows) or very slow (eg. Soil creep).
Landslides
• After periods of heavy rain, saturated overlying rock
• Mass becomes heavy and rapidly slides down conclave plane
• Involves undercutting of a slope through erosion
• Creates rotational slump, enabling mass movement
Mudflow
• Needs steep slopes, saturated soil after heavy rain + lack of vegetation (no water absorption)
• Involves lots of soil saturation + impermeable sub-soils
• Impermeable sub-soils allow for landmass to slide down surface
Rockfall
• Involves freeze-thaw + chemical weathering over time
• Bare rock gradually erodes + scree slope is formed
• Slow process
Soil Creep
• Very slow movement, gentle slopes
• Soil particles expand when wet, increase in size, then shrink in the day (slow movement)
• Soil moves down slope slowly over time
What is Longshore Drift?
The process by which pebbles and sand are transported along a beach.
Characteristics of Destructive Waves
• More powerful, strong backwash + removal of sediment from beaches (erode beaches
• Most common in winter or stormy conditions
• Shorter wavelengths, higher in height + frequency
Characteristics of Constructive Waves
• Less powerful waves, deposit material on a beach with strong Swash
• Most common in summer + calm weather
• Longer wavelengths, lower in height + frequency
What is a Spit?
A long narrow ridge of sand and shingle. One end is attached to land whilst the other extends into the open sea or an estuary.
How are Spits formed?
1) Longshore Drift transports + deposits sand and shingle along the coast
2) The coastline changes direction, sediment is deposited in the open sea and builds up a ridge
3) The landform grows and extends into the sea, often being curved by the wind and waves
4) The spit grows and can support vegetation and human activity over time
5) Salt marshes form behind the spit and create habitats for wildlife
What kind of Landforms might you expect to find in the Upper course of a river?
• V-shaped valleys
• Waterfalls
• Gorges
• Interlocking spurs
How are Waterfalls formed?
1) Water flows from hard rock onto a softer rock
2) Erosion of the soft rock undercuts the hard rock, hydraulic action creating an overhang + plunge pool
3) The hard rock eventually collapses + is deposited in the plunge pool (abrasion on soft rock)
4) The waterfall retreats upstream and creates a gorge as the process repeats itself
What Landforms might you expect to find in the Middle and Lower Courses of a River?
Middle Course:
- Meanders
- Ox-bow lakes
Lower Course:
- Floodplains
- Levees
How are Floodplains and Levees formed?
• Periods of high discharge, river floods and spreads water + alluvium across land
• River returns to normal conditions, layer of alluvium deepens + forms floodplain
• Levees are created when alluvium builds up on river bank
What are Hard Engineering strategies? Name some examples.
Human-made structures that work against natural processes to protect the coastline. Tend to be more expensive + structures need to be continually maintained or rebuilt.
Examples:
- Sea Wall
- Groynes
- Rock Armour
- Offshore Reef
What are Soft Engineering strategies? Name some examples.
Adaptations that work with nature to protect the coastline. Tend to be cheaper + easier to maintain.
Examples:
- Beach Nourishment
- Managed Retreat
- Doing nothing
- Cliff Stabilisation
What are the options for Coastline Management (SMPs)?
• Doing nothing
• Hold the Line (maintain sea defences)
• Retreat the Line (allow some flooding)
• Advance the Line (build new defences)
What do Councils have to consider when creating Shoreline Management Plans?
• Number of people + properties threatened by coastal erosion
• Cost of replacing infrastructure (eg. Roads)
• Historic features and natural landforms (economic value for tourism)
