Coastal landforms Flashcards
Coasts
The 6 erosional landforms.
1= C_____
2= W____-___ p________
3= H__________ & B____
4= C_____
5= A______
6= S______
1= Cliffs
2= Wave-cut platforms
3= Headlands & Bays
4= Caves
5= Arches
6= Stacks
The 8 depositional landforms:
1= B________
2= S______
3= O_______ B____
4= T________
5= B_______ b_______
6= S_____ d______
7= M__________
8= S___________
1= Beaches
2= Spits
3= Offshore bars
4= Tombolos
5= Barrier beaches
6= Sand dunes
7= Mudflats
8= Saltmarshes
What are cliffs and what happens to them?
Cliffs form as sea erodes the land. Over time, they retreat due to the action of the waves and weathering.
Explain the formation of a wave-cut platform.
1= Notch forms due to erosion
2= Forms into a cave
3= Collapse and retreat
4= Repeated retreat leaves a larger wave-cut platform.
What causes headlands and bays to form?
Headlands and bays form where there are bands of alternating hard and soft rock
List all the cliff profile features.
1= Crack
2= Cave
3= Arch
4= Stack
5= Stump
Give an example of a disconcordant coastine.
Dorset
How do beaches form?
Beaches form when constructive waves deposit sediment on the shore - they are a store in the coastal system.
Explain the differences between shingle and sand beaches.
Shingle beaches are steep and narrow and made up of larger particles, wheras sand beaches are wide and flat and made up of smaller particles.
Spits tend to form when the coast suddenly changes _________, such as across a river mouth. ____________ ______ continues to ________ material across the mouth, leaving a ____ of sand ________ ____ into the sea.
direction
Longshore drift
deposit
spit
sticking out
How are bars formed?
Bars form when a spit joins two headlands together. This can occur across a bay or across a river mouth. A lagoon then forms behind the bar.
What is an offshore bar?
This is where bars form off the coast when material moves towards the coast - normally as sea level rises. They may remain partially submerged by the sea.
What is a tombolo?
A bar that connects the shore to an island.
What are barrier islands?
Barrier islands are long, narrow islands of sand or gravel that run parallel to the coast and are detatched from it.
How do barrier islands form?
They tend to form in areas where there is a strong supply of sediment, a gentle slope and fairly powerful waves. They form when a bar is eroded in sections, causing breaches and the bar to become separated from the coast.
What usually forms behind a barrier island?
A lagoon or a saltmarsh, due to the fact that it is sheltered from wave action.
Explain the formation of a sand dune.
Sand dunes form when deposited sand is moved up the beach by wind. Sand trapped by driftwood is colonised by plants and marram grasses. Vegetation stabilises and enncourages more sand to accumalate.
What are the five key stages of a sand dune?
1= Embryo dunes
2= Grey dunes
3= Yellow dunes
4= Fore dunes
5= Mature dunes
Explain the characteristics of embryo dunes.
Very harsh conditions, vegetation exposed to the elements. Miniscule humus layer and plants do not grow to more than 1m tall.
Explain the characteristics of mature dunes.
Stable conditions, an grow up to 10-15m in height. Humus layer increases as it goes further inland.
What is climax vegetation?
Climax vegetation represents the final, stable stage of ecological succession where a plant community reaches equilibrium with its environment, characterized by a diverse and self-sustaining ecosystem.
What is psammosere?
Psammosere is a term used to describe the process of ecological succession on sand dunes, where pioneer plants initially colonize the bare sand, followed by other species as the environment changes.
What are mudflats and how to they form?
Mudflats form in sheltered, low energy environments, such as behind spits. As silt and mud are deposited by the river or tide, mudflats develop. They are colonised by vegetation that can survive high salt levels and long periods of sumergence.
How are saltmarshes formed?
When a mudflat traps more and more mud and silt, it gradually builds upwards to create an area of saltmarsh that remains exposed for longer between tides.
What is submergence?
This is where the sea level rises relative to the coast, the sea submerges the existing coastline, creating different landforms, such as rias, fjords or dalmation coasts.
How do rias form?
Rias form when river valleys are partially submerged. Rias have a gentle and long cross profile and are wide and deep at the mouth, becoming narrower and shallower the further inland they go.
How do fjords form?
Fjords form in drowned glacial valleys. They are straight and narrow, with very steep sides. They have a shallow mouth caused by the threshold (material deposited by the glacier). They get deep inland - 1000m in some places.
How do dalmation coasts form?
Dalmation coasts form in areas where valleys lie paralell to the coast. An increase in sea level floods valleys, leaving islands paralell to the coastline.
What is emergence?
Emergence is where sea level falls relative to the coast and a new coastline emerges from the sea. This creates different landforms such as raised beaches or relict cliffs.
How do raised beaches form?
Raised beaches are formed when the fall in sea level leaves beaches above the high tide mark. Over time, beach sediment becomes vegitated and develops into soil.
How do relict cliffs form?
Cliffs above raised beaches are no longer eroded by the sea, and slowly get covered by vegitation. They are called relict cliffs, and it is not uncommon to see caves, arches and stacks within them, but they may be degraded due to weathering.
