Coasts Revision Flashcards
What is the littoral zone?
The littoral zone - is the area of the coast that can be affected by wave action.
It is a dynamic zone which means its constantly changing due to the interaction between processes on land and in the sea.
These changes can be:
- Long - term due to climate or sea level changes
- Short term due to the tides, waves, and storms
What are the four parts of the littoral zone?
- Backshore is usually beyond the influence of wave action but can be affected during storm events
- Foreshore is the intertidal area between high and low tide
- Nearshore is the breaker zone where friction between the seabed and the waves causes them to break
- Offshore is the area outside the influence of waves
What are concordant coasts?
A concordant coastline is a coastline where the same type of rock runs parallel to the coast, and the layers of rock are folded into ridges. Concordant coastlines are also known as longitudinal or Pacific type coastlines
Example: Durlston Bay
What are discordant coasts
A discordant coastline is a coastline where bands of different rock types run perpendicular to the coast, resulting in the formation of headlands and bays
Example: Lulworth cove
Eustatic sea level change
Eustatic sea level change is a global change in the amount of water in the oceans or the shape of the ocean basins.
Caused by changes in ocean water volume and temperature
Impact seen in tropical oceans
What is Isostatic sea level change?
Isostatic sea level change is a local/regional change in sea level that occurs when the land rises or subsides relative to the water
The Earth’s crust floats on a denser underlying layer (asthenosphere), which is in balance when the weight of the crust is exactly balanced by its buoyancy
The addition of a load at a particular point of the crust (water, ice or increasing sediment at a delta) upsets the equilibrium and some of the asthenosphere floats away, causing isostatic depression as the land level falls
What are Emergent Coasts?
Emergent coastlines are coastlines that have been created when the sea level has fallen relative to the land. This can happen when the land is uplifted or when the sea level falls
What are Submergent Coasts?
Submergent coasts are coastlines that have been submerged underwater due to a rise in sea level. They are the result of areas of land that were once part of the terrestrial land being inundated by the sea
What are the characteristics of a high energy coast?
- Destructive waves
- Exposed to strong winds and long fetches
- Higher rates of erosion and deposition
- Tend to be rocky coasts
- Steep cliffs - marine cliff profile
- Less steep cliffs - subaerial cliff profile
Headlands, wave - cut platforms
What are the characteristics of a low energy coast?
- Constructive waves
- Sheltered locations with short fetch
- Higher rates of deposition than erosion
- Sandy beaches, salt marshes, estuarine and tidal mud flats
- Gentle relief
- Sediment from land and sea
Beaches, spits, coastal plains
Why do coastal plains occur?
Coastal plains usually occur where the land gradually slopes down towards the sea, tend to be low relief
Coastal plains include both:
- Sandy coastlines
- Estuarine coastlines
What are primary coasts?
dominated by land-based processes, such as deposition from rivers
What are secondary coasts?
dominated by marine erosion or deposition processes
Wave tide types?
Microtidal coasts – have a tidal range of 0-2m
Mesotidal coasts – have a tidal range of 2-4m
Macrotidal coasts – tidal range greater than 4m
Dalmatian coastlines?
These coastlines are named after the Dalmatian region of Croatia. They feature long islands and coastal inlets that run parallel to the coastline. These Dalmatian types normally occur in high energy environments from where there is eustatic or isostatic change creating a submerging coastline.
