Coasts Flashcards
What is wind?
Areas go high pressure and low pressure form.
The movement of high pressure to low air pressure.
How are waves formed?
Frictional drag between wind and the sea surface.
This makes the particles move in a circular motion/orbit of water.
What does the term fetch mean?
The area of surface over which the wind blows in one direction.
What is the wave crest?
The highest point of a wave.
What is the wave trough?
The lowest point of a wave.
What are some characteristics of constructive waves?
Low surging waves with a long wavelength
Strong swash and weak backwash
Beach gain
What are some characteristics of deconstructive waves?
Local storms are responsible for these
High, plunging waves with a short wavelength
Beach loss
Weak swash and strong backwash
What is wave refraction?
This occurs on irregular shaped coastlines, it is when the front of a wave reaches shallow water and the frictional drag increases the wave velocity. The waves then speed up and wave height increases, this then causes deposition in the bays.
What causes tides?
Gravitational pull of the moon and the sun.
Through the earths rotation
What are ocean currents?
Ocean currents can be found at both the bottom of the ocean and on the surface, the shape of land can influence ocean currents.
What are the inputs of sediment?
Cliff erosion
Eroding, dunes, spits
Beach recharge
Offshore bars
What are the transfers of sediment?
Longshore drift
Currents
Saltation
Wind
What are the stores of sediment?
Offshore banks Spits Bars Beaches Dunes
What are sediment cells?
The areas along coastlines or near the coastline where material is largely self contained.
They are considered a closed sub system
Tend to be between headlands and peninsular which act as natural carries.
How are headlands and bays formed?
When hard rock is left as the soft rock between is eroded.
In discordant coastlines
Differential erosions.
What is a discordant coastline?
Hard rock, soft rock, hard rock etc, VERTICAL SEPERATION
What is a concordant coastline?
HORIZONTAL SEGREGATION
How are wave cut platforms formed?
A gentle sloping platform of rock is stretching out into the sea, <5degree angle
Abrasion cuts into the rock
The platform causes the waves to break further out and this reduces erosion
A wave cut notch forms and undercuts cliff
Slowly retreats inland towards the shoreline
What are the other features of coastlines?
wave cut notch, cave, stack, stump and arches
What is a drift aligned beach?
The waves break at an angle and so the swash occurs at an angle.
Therefore sediment is transported at an angle down the beach via longshore drift.
What is a swash aligned beach?
Where the waves break parallel to the coast.
Swash and backwash move the sediment up and down the beach
Curved and concave beaches
What are some features of spits?
Long and narrow
Accumulations of sand or shingle
May have a hooked or recurred end
Found where the coast changes direction
What is needed to form sand dunes?
Sand
Prevailing dominant winds
Saltation, surface creep
Some sort of obstacle or vegetation to trap sand
What are the stages of sand dune of formation?
Embryos Foredunes/yellow dunes Dune stacks Grey dunes Climax community
What is eustatic sea level change?
Global change in sea level
Can rise or fall
Climate warming is the cause, eg glacier melting
Thermal expansion and contraction of water
What is tectonic sea level change?
Large scale vertical movement of crust
Creation of volcanic islands could displace water and sea level
What are the stages of sea level change
- Eustatic fall
- Eustatic rise
- Istotatic change
- Readjusted
What is a Dalmatian coast?
Mountain ranges running parallel to the coast.
River valleys are running parallel to the coastline.
What is a Ria?
A flooded river valley.
Submergent feature.
What sea level change is local and which is global?
Isostatic is local
Eustatic is global
