Key Terms Coasts Flashcards
What’s the order of the littoral zone?
Offshore, near shore, foreshore, back shore.
Concordat coastline? What’s formed?
Rock layers parallel - coves form.
Discordant coastline? What’s formed?
Rock layers perpendicular- headlands form creating bays
Haff coastline?
Lagoons found behind deposits parallel to the coast (concordant)
Lithology (rock)
Rock types and their general characteristics
Subaerial processes?
Weathering and mass movement (they weaken rock, allowing erosion to take place more easily)
Plant succession?
The change to a plant community because the growing conditions have changed enough, due to other plants, to allow new plants to grow there and take over.
Flocculation
Tiny clay particles stuck to one another.
Brackish water?
Slightly salty water
Salt marshes
- Common in low energy environments of estuaries and sheltered bays.
- Salt marshes found where rivers deposit sediment on the edges of estuaries.
- Pioneer plants trap more sediment to grow the sal marsh and let more plants grow.
Sand dunes
- vegetation captures sand that’s blown towards the land.
- embryo dunes establish and collect more sand.
- dunes grow larger
Yellow dunes
Highest type of dune, have marram grass on top.
Slacks (dunes)
Dips in the sand dunes
Destructive waves
- Wave angle 120°
- 13-15 per minute
- more common than constructive waves
- stronger backwash than swash
- removed sediment
- circular movement
- steep beach
Constructive wave
- stronger awash than backwash
- 6-8 per minute, less common
- Deposit sediment
- elliptical shape
- gentle sloping beach
Hydraulic action
Water forces air into rock cracks, causing the rock to shatter when the waves falls down.
Corrosion
CO2 dissolves in sea water and this can dissolve rocks such as limestone.
Abrasion
Destructive waves repeatedly throw sand and rocks at the cliff face and hit the cliff themselves, causing it to wear away.
Attrition
Rocks and pebbles hit are moved around by waves and hit each, causing them to become small and round.
Wave cut notch
Destructive waves reach the base of a cliff, hydraulic action and abrasion cause it to wear away, leaving a notch.
Wave cut platform
Base of cliff eroded, gravity makes it collapse, leaving sloping rock in between high and low tide levels. -coastal recession.
Order of cave, arch…
Crack, cave, arch, stack, stump.
Longshore drift
Ideally 30° swash that pushes sediment onto the beach, 90° backwash pulls sediment back along with gravity, this occurs until a natural obstacle (bay), or artificial obstacle (GROYNE).
Beach morphology
Surface shape of a beach.
Offshore bar
Destructive waves break before reaching the beach, and throw material into a heap near the shore.
Barrier beach
a sand ridge that rises slightly above the surface of the sea and runs roughly parallel to the shore
Spit
an extended stretch of beach material that projects out to sea and is joined to the mainland at one end.
Tombolo
Narrow ridge of sand linking an island to the mainland.
Headland
Part of the coast that extends further out to sea than the coast.
Cuspate foreland
Low lying headland. Formed when longshore drift happens in opposite directions, forming two spits that meet.
Sediment cell(littoral cell)
Part of a coast that is linked together by all of the processes (cliff erosion, longshore drift).
Positive and Negative feedback
A natural system may cause a change that is exaggerated or dampened in the future - e.g: rockfall protects base of cliff from erosion.
Weathering
Wind, rain- cause weakness in rocks
Mass movement
Rockslides.
Eustatic change
Change in sea level
Isostatic change
Change in land level
Emergent coastline
Result of isostatic rebound (land rises up).
- can make raised beaches
Submergent coastline
Result of isostatic sinking.
Ria
Flooded RIVER valley. Frozen floor made water erode sides, creating steep sides.
Fjord
Flooded GLACIATED valley. Glaciers eroded U-shaped valley, ice melted and sea levels rose, causing the valley to flood.
Fjärd
Flooded inlet with low rocky banks formed by post glacial drowning.
Dalmatian coast
Concordat coastline
Thermal expansion
Heat causes water particles to expand, meaning sea levels rise
Dredging
Removing sand and gravel from the sea bed (used to deepen the sea for ports)
Storm surge
Low pressure causes a dome of water to rise up. This then surges ashore when the low pressure area moved ashore.
Hard engineering
- Don’t work with the environment
- high cost
- don’t last long
- more effective than soft
- very visible
Soft engineering
- Work with environment
- cheaper
- last longer
- not always visible
Groynes
Barrier to longshore drift.
Sea walls
Stop waves.
Rip-rap
Granite boulders that break up waves.
Revetments
Parallel sloped wooden walls that slow waves down.
Offshore breakwaters (reefs)
Rock boulders in the WATER that break waves up and slow them down.
Gabions
Pebbles in wire baskets that break up waves.
Beach nourishment
Replaces beach sediments that have gone.
Cliff regrading
Makes dangerous cliffs safe by cutting them back.
Cliff drainage
Drain water out of unstable cliffs to stabilise them.
Dune stabilisation
Stabilising dunes through re plantation and geofabrics.
Managed retreat
An area set aside for the sea to flood.
Cost benefit analysis (CBA)
Comparing the cost of coastal defences with the value of the land.
Environmental impact assessment (EIA)
Looks at the impact on the environment of decisions.
