Geography unit B

el nino

The trade winds decrease, air pressure patterns in the South Pacific are reversed, flow of water away from South America decreases and warmer temperature.

Surface currents

are caused by the influence of prevailing winds blowing steadily across the sea

Upwelling currents

where the ocean currents move cold water, rich in nutrients, from the ocean floor to the surface

Hurricanes

Low-pressure systems that bring heavy rainfall, strong winds, and high waves and cause other hazards such as floods and mudslides

3 conditions for hurricane

**warm water, damp air,** **winds that meet**

Geological structure

the disposition and nature of the materials on the coast

Processes affecting coastline

erosion & deposition

Sea level changes

interact with erosional or depositional processes to produce advancing or retreating coastlines

Waves

the movement of water molecules within the ocean, and are restricted to the surface layers of our oceans and seas

Why do waves break?

a critical point is reached where the top of the wave (the CREST) curves over and creates a breaking wave

swash

The movement of water and sediment up a beach, determined by the prevailing wind

backwash

The movement of water back down the beach, determined by the slope of the beach

longshore drift

moves sediment in one general direction along the coastline in a zig-zag fashion, governed by the prevailing wind and interaction between swash and backwash

Constructive waves

swash is stronger than bakwash

Destructive waves

backwash stronger than swash

Spilling breakers

Break slowly as they approach the shore, and wave energy is spread over a large area of the beach.

plunging breaker

Breaks quickly with substantial force and wave energy is concentrated over a small area of the beach.

Surging breakers

Rush up a very steep beach without dissipating much energy in the beach layer known as swash.

What causes headlands and bays

Differentiated rates of erosion due to different levels of resistance in the geology

How are beached formed

Beaches form in sheltered environments, such as bays. When the swash is stronger than the backwash, deposition occurs.

Spits

A spit is a landform of coastal deposition, an extended stretch of beach material that sticks out to sea and is joined to the mainland at one end. Caused by longshore drift.

The formation of a spit

Longshore drift transports material along the coast, and spit forms when material is deposited due to reduced energy when the sea meets a river.

tombolo

spit joining the mainland to an island

Sand dunes formation

Sand dunes are small ridges or hills of sand found at the top of a beach, above the reach of the waves, sand is deposited by the wind around an object such as a rock, forming embryo dunes

la nina

The trade winds increase, increasing upwelling off South America, lower-than-normal sea surface temperatures

oceanic conveyor belt

a constantly moving system of deep ocean circulation driven by temperature.

Upwelling

deep cold nutrient water rising on the surface

Thermohaline circulation

the conveyor belt- transfer of energy by deep sea currents, cold water sink and moves towards the equator

thermocline

layer between surface warm water and deep cold water.

halocline

change in water salinity levels as the depth change

EEZ

exclusive economic zones- prescribed by UN that a state has speacial rights regarding exploration and use of marine resources

Subaerial weathering

weathering of caves and large sedinments caused due to waves.

isostatic

local sea level change- the height of the land rises or falls depending on pressure out on by ice.

fetch

the stretch of ocean water over which wind was blown

coral reefs

underwater ecosystem characterised by reef building corals

Mangroves

shrub that grow in costal saline water

concordant coast

ocean infiltration and erosion of soft material

discordant coast

when the bands of different rock types run perpendicular to the coast

gabion

wire meshcages filled with pebbles

groyne

wooden barriers constructed at right angles

revetments

traditionally been wooden slatted barriers constructed towards the rear of beaches to protect the base of cliffs

sea walls

built in front of cliffs to protect against waves

downwelling

occurs when surface water becomes more dense and sinks to the bottom

onceanic carbon cycle

photosynthesis, turns carbon dioxide into organic material, this carbon sinks to the bottom causing upper part to have low carbon concentration.