Coastal Environments Flashcards
Coastal Processes
What are coasts?
Coasts are the meeting point of the land and sea and are an open system with inputs(sediment), transfers(longshore drift), stores(beach) and outputs(water).
Coastal Processes
What is the fetch?
The distance the wind blows over the sea.
Coastal Processes
What is hydraulic action?
Sheer force of the waves hitting the coast.
Coastal Processes
What is attrition?
Material (rocks,shingle) are carried by the waves and bump against each other and are worn smaller and smoother. This type does not really erode the coast but forms shingles and sand.
Coastal Processes
What is corrosion (or solution)
Seawater is slightly acidic and this gradually dissolves some types of coastal rock (limestone etc.)
Coastal Processes
What is Abrasion?
Waves pick up material and hurl it at the coast.
Coastal Processes
What are the 3 factors affecting the height and strength of waves?
- Fetch
- Amount of time wind blows
- Strength of wind
Coastal Processes
What is traction?
Large heavy material is dragged along the sea floor.
Coastal Processes
What is saltation?
Smaller material is bounced along sea floor.
Coastal Processes
What is Suspension?
Fine material is held in water and travels along.
Coastal Processes
What is solution?
Dissolved material is carried in water.
Coastal Processes
What is longshore drift and can you explain the process?
- It is the main process of deposition and transportation along the coast.
- Influenced by prevailing wind, waves approach beach at angle.
- Swash carries material up the beach.
- As swash dies away, the backwash carries material down at a right angle due to the influence of gravity.
- The process repeats, transporting material along the beach in a zig-zag movement.
Coastal Processes
What is weathering?
Breakdown of rocks in-situ (orginal place). Weathering does not involve the movement of material and this makes it different from erosion.
Coastal Processes
What is sub-aerial weathering?
Are land-based processes and occur above the waterline. They include weathering and mass movement, which happen on the cliff rocks.
Coastal Processes
Explain mechanical weathering (with example):
Mechanical weathering physically breaks up rock:
One example is freeze thaw weathering. This is when water gets into cracks and joints in the rock and freezes. This causes the cracks and joints in the rock to expand and over time pieces of rock break apart.
Coastal Processes
Explain biological weathering:
Takes place when rocks are worn away by living organisms.
Trees and other plants can grow within cracks of rocks.
Animals can disturb ground.
Coastal Processes
Explain chemical weathering:
Occurs when rocks are broken down by a chemical process.
Rainwater is slightly acidic through absorbing CO2 in the atmosphere.
This reacts with minerals in the rock.
Rock-type affects rate of weathering. (limestone is especially vulnerable)
Coastal Processes
What is mass movement?
The downhill movement of material under the influence of gravity.
Coastal Processes
What is sliding?
A movement of material which remains together until hitting the bottom of a slope.
Coastal Processes
What is slumping?
Involves a large area of land moving down the slope in one piece. Due to the nature of the slip, it leaves behind a curved surface.
Coastal Landforms
What is a headland?
Section of hardrock jutting out into the sea,
Coastal Landforms
What is a bay?
Inlet of the sea where the land curves inwards.
Consist of soft rock/material.
Coastal Landforms
What is a wave-cut platform?
A wide gently sloped surface found at the foot of a cliff,
Coastal Landforms
Explain the formation of a headland:
Headlands are formed at discordant coastlines where there are alternating bands of hard rock and soft rock at right angles to the coastline, which means that the soft rock gets eroded faster than the hard rock (since it is less resistant) creating a bay and a protruding headland.
Coastal Landforms
Explain the formation of a bay:
Bays are formed at discordant coastlines where there are alternating bands of hard rock and soft rock at right angles to the coastline, which means that the soft rock gets eroded faster than the hard rock (since it is less resistant) creating a bay and a protruding headland.
Coastal Landforms
Explain the formation of a cliff:
Cliffs tend to be located on a headland due to erosion from wave action. The base of the cliff is eroded through a number of ways: Hydraulic action, abrasion and corrosion. The rock type will affect cliff gradient or steepness. Cliffs with soft rock are gently sloping while cliffs with hard rock are steep.
Coastal Landforms
Explain the formation of a wave cut platform:
- Due to wave action (sea hitting) on the base of the cliff between the high and low water mark, wave-cut notch is formed.
- Abrasion, corrosion and hydraulic action further extend the wave cut notch back into the cliff.
- The undercutting of the cliff leads to instability and collapse of the cliff.
- Backwash of the waves carries away eroded material, leaving behind a wave cut platform.
- Process repeats and cliff continues to retreat.
Coastal Landforms
Explain the formation of a cave, arch, stack and stump:
- Found on a headland due to wave action and sub-aerial weathering.
- Weakness in the headland are exploited on both sides by erosional processes of hydraulic action, abrasion and corrosion.
- Cracks begin to widen, abrasion will begin to wear away at the forming cave.
- The cave will become larger and eventually break through the headland to form an arch.
- The base of the arch continually becomes wider and thinner through erosion below and weathering from above.
- Eventually the roof of the arch collapses, leaving behind an isolated column of rock called a stack.
- The stack is undercut at the base by wave action and sub-aerial weathering above until it collapses to form a stump.
Coastal Landforms
Explain the formation of a spit:
- Sediment is transported by longshore drift.
- Where coastline changes direction, shallow, shelted areas allow for deposition of sediment.
- Due to increased friction, more deposition occurs.
- Eventually a spit builds up to sea level and extends in length.
- If wind changes direction, wave pattern alters resulting in hooked end.
Coastal Environment Change
What are the 4 influences affecting coastlines?
Influence of:
1. Geology
2. Vegetation
3. Sea-Level Changes
4. People
Coastal Environment Change
How does Geology influence the coastline?
- Hard Rock: Coastlines of more resistant rock take longer to erode and produce rugged landscapes such as headlands.
- Soft Rock: Coastlines of less resistant rock erode quicjer and form low, flat landscapes like beaches and bays.
Coastal Environment Change
How does Vegetation influence the coastline?
The largest influence of vegetation is to assist in protecting and preserving coastal landforms. Examples include sand dunes, salt marshes and mangroves.
Coastal Environment Change
How does sea-level changes influence the coastline?
- Submersion: Rising sea levels produce submergent coastlines with rias and fjords.
- Emergence: Falling sea levels produce emergent coastlines with relic features such as raised beaches, cliffs with caves, arches etc.