Coastal landforms Flashcards
Define a bay
A low lying inlet of land on the coast. Formed by soft and hard rock types eroding at different paces
Define headland
A high area of land that extends out into the sea. Hard rock
Define wave-cut platforms
A flat area in front of a cliff,
just below the low tide mark. Formed when waves eroded the cliff. left a flat platform behind
How is a wave cut platform formed
- Sea attacks base of cliff between high and low water mark
- Wave cut notch formed by erosional processes such as abrasion and hydraulic action- dent in cliff usually at level of high tide
- As notch increases, cliff becomes unstable and collapses, leading to retreat of cliff face
- Backwash carries away eroded material, leaving wave cut platform
- Process repeats, cliff continues to retreat
Caves, arches stacks and stumps
- Crack widened in headland through erosional processes of hydraulic action and abrasion
- As waves continue to grind away at crack, begins to open up to form a cave
- Cave becomes larger, breaks through headland to form arch
- Base is arch becomes wider through further erosion, roof collapses making a stack
- Stack is undercut at base, collapses to form stump
3 examples of depositional landforms
Beaches
Spits
Bars
How are be beaches formed?
from eroded material that’s been transported from elsewhere and deposited by sea. Waves have limited energy, beaches for in sheltered areas like bays. Constructive waves
Sandy beaches found in bags where water shallow and waves have less energy. Pebble beaches form where cliffs been eroded, higher energy waves.
Cross profile called beach profile
Lots of ridges called berms
Show lines of high tide and storm tides
Sandy beach typically gentle sloping profile, shingle beach steeped, Size of material larger at top, high energy storm waves. Smallest material nearest water, waves break here and break down rock through attrition
What are spits
An extended stretch of sand or shingle jutting out into the sea from land. Occur when change in shape of landscape or at river mouth
How is a spit formed?
- Sediment carried by longshore drift
- When there’s a change in shape of coastline, deposition occurs. Long thin ridge of material deposited= the spit
- Hooked end can form if change in wind direction
- Waves cannot get past spjt, the water behind spit is sheltered. Silts are deposited here to form salt marshes or mud flatscreens
What is a bay?
Spits can grow across a bay and join 2 headlands together= called a bay.
Trap shallow lakes, called lagoons.
Dorset coastline
South of england
Swanage is example of headland and bay
Old Harry Rocks is example of caves, stacks and stumps
Chelsie Beach is example of a bar
Swanage bay
Area around swanage is made up of bands of hard and soft rock. Soft rock is clay and sands, hard rock is chalk and limestone. Clay eroded away quicker than limestone and chalk. Forms headlands and bags, creates Swanage Bag and 2 headlands- Ballard Point & Durlston Head
Old Harry Rocks
Located on headland between Swanage and Studland Bay. Headland made out of chalk- hard rock. Headland juts out into sea more vulnerable to high energy waves. Caused formation of Old Harry, a stack. Eventually will collapse to form stump
Chesil Beach
Example of a bar. Sediment deposited over time to form spit. Spit continued to join to Isle of Portland. Behind spit there is The Fleet- a lagoon