Coasts

Question 1

Types of waves

Answer 1

Constructive
Destructive

Question 2

Constructive wave

Answer 2

Build beaches
Smaller wave height and less frequent
Strong swash moves sediment up the beach
Weak backwash carries away little sediment
Builds gently sloping beach profile

Question 3

Destructive wave

Answer 3

Destroys beaches
Larger wave height and more frequent
Weak swash moves little sediment up the beach
Strong backwash carries away lots of sediment
This builds a steep beach profile

Question 4

Coastal processes

Answer 4

Movement
Weathering
Erosion
Transportation

Question 5

Types of Movement processes

Answer 5

Soil creep: Surface runoff slowly moving soil downhill
Slumping: Area of saturated land slips downhill

Question 6

Types of Weathering processes

Answer 6

Physical(freeze-thaw): Rock breaks due to changes in temperature
Biological: Plants and animals break up the rock
Chemical: Acid in rainwater dissolves the rock

Question 7

Types of Erosion processes

Answer 7

Corrosion(Solution): Material dissolved by the river
Abrasion(Corrasion): Load wears away river channel
Hydraulic Action: Force of current dislodges loose material
Attrition: Load collides

Question 8

Types of Transportation processes

Answer 8

Tration: Rolling of large load
Saltation: Bouncing of smaller load
Suspension: Fine material held within the water
Solution: Rocks dissolved within the water

Question 9

Discordant coastlines (how bays and headlands are formed)

Answer 9

Where bands of rock of alternating resistance run perpendicular to the coast. Bays form where weak (less resistant) rocks (such as sands and clays) are eroded, leaving bands of stronger (more resistant) rocks (such as chalk, limestone and granite) forming a headland.

Question 10

Cliffs, wave-cut notch and wave-cut platforms

Answer 10

In areas of more resistant cliff material erosion is greatest when waves break at the foot of a cliff. This causes erosion at the base of the cliff.
* This creates a wave-cut notch in the base of the cliff. As the notch increases in size the weight of the
cliffs above become too much and the cliff collapses.
* The material from the cliff is broken up through attrition and some of it remains at the base of the cliff forming a terrace known as a wave cut platform.

Question 11

Caves, arches, stacks and stumps

Answer 11

Even hard rock, that forms headlands, contains weaknesses. Hydraulic action forms cracks in the rock until an opening is formed.
* As the waves continue to attack the rock it is hollowed out to form a cave.
* Further erosion means that the cave is widened and deepened until it becomes an arch.
* Widening of the arch through undercutting means that material becomes unsupported and collapses
into the sea forming a stack.
* Further undercutting causes the stack to collapse leaving only a stump.

Question 12

Longshore drift

Answer 12

Material is moved along the coast by a process
called Longshore drift. This is a zig-zag
movement. It is pushed along by the prevailing
wind. The waves rush up the beach at an angle
and return to the sea at right angles to the
coastline

Question 13

Beach

Answer 13

Are made up of eroded material that has been transported and then deposited by the sea.
Sandy beaches are usually found in bays where the water is shallow, and the waves have less energy.
Pebble beaches often form where cliffs are being eroded, and where there are higher energy waves.

Question 14

Deposition

Answer 14

Occurs when waves have limited energy, so beaches often form in sheltered areas like bays.

Question 15

The formation of Spits

Answer 15

A spit is a long beach made up of sand and
shingle that extends out to sea. It is found:
* In areas of shallow water.
* On a bend in the coastline.
* Eroded material is carried along the
coast by longshore drift. This action continues
until the prevailing wind and waves force the
spit to start to curve.

Question 16

Soft engineering

Answer 16

Soft engineering options are often less expensive than hard engineering options. They are usually also more long-term and sustainable, with less impact on the environment.

Question 17

Types of Soft engineering

Answer 17

Beach Nourishment: This replaces beach or cliff material that has been removed by erosion or longshore drift.
Beach Reprofiling: The sediment is redistributed from the lower part of the beach to the upper part of the beach.
Dune Stabilisation: Marram grass planted on sand dunes stabilises the dunes and helps to trap sand to build them up.
Managed Retreat: This is where areas of the coast are allowed to erode and flood naturally. Usually, these will be areas considered to be low value.

Question 18

Hard engineering

Answer 18

Hard engineering involves the construction of physical structures to protect coasts against the erosive power of waves. Hard engineering options tend to be expensive, long-term options. They may also have a high impact on the landscape or environment and be unsustainable.

Question 19

Types of hard engineering

Answer 19

Sea wall: A seawall is a structure made of concrete built parallel to the shore at the transition between the beach and the mainland to protect the inland area against wave action and prevent coastal erosion (resist storm surges).
Groynes: A groyne is a long narrow structure built out into the sea from the beach to limit the movement and loss of beach material (sand and shingle).
Rock Armour or Rock barriers: Riprap is large boulders interlocked together to form rock revetments that can be used to control erosion by armouring the beach face and dissipating wave energy.

Question 20

Coastal management is important?

Answer 20

The management of coastlines is needed to protect our land use such as settlements, tourism, roads and farming. The cost-benefit of any scheme must be balanced when deciding on the type of management for an area.

Question 21

Holderness coast causes

Answer 21

Mostly comprised of boulder clay
The cliff foot erosional processes of hydraulic action and abrasion undercut the cliffs at their base and erode the soft material.
The strong currents of the North Sea rapidly transport material along the shore.
Most of Holderness is comprised of soft boulder clay, however, the northernmost part of the coastline is made up of chalk. Chalk is a more resistant rock and so less easily eroded.

Question 22

Holderness coast effect

Answer 22

This has resulted in 14 villages being lost from the
coastline since Roman Times.
Ringborough Farm has lost 145 acres since 1939, meaning that half of the farm’s land has been lost to the sea. The farmer has also been forced to diversify
The rapid rate of cliff recession has meant that there has been a need to protect areas of high value with hard engineering defences e.g., the settlement of Hornsea on the Holderness Coast.
Without replenishment, Spurn Point may erode; this area is an SSSI (site of special scientific interest) and it is an important habitat for many bird species

Question 23

Holderness coastal management

Answer 23

Use of groynes to trap moving beach material and provide a protective beach in front of the cliff
The construction of sea walls and revetments as wave-resistant structures at the base of the cliffs
Artificial off-shore breakwaters like tyres and concrete blocks, forcing waves to break off-shore.
Sea wall used to protect Easington Gas Station (cost 4.5 million)

Question 24

Hurricane conditions

Answer 24

Hurricanes need a lot of heat to form and a sea surface temperature of at least 26°C, which is why they usually occur over tropical seas. They also need to be between 5 and 20° north or south of the Equator.

Question 25

Hurricane formation

Answer 25

Tropical storms begin when thunderstorms move over tropical ocean water.
* Tropical oceans (at least 27°C) warm the air above it.
* This warm, moist air starts to rise.
* Because this air is evaporating, there is less air left near the surface. This causes an area of
low air pressure.
* As the warmed, moist air rises and cools, the water in the air forms clouds.
* As the storm moves over the ocean, it picks up more warm moist air and grows. The speed of
its winds increases as more air is sucked in.
* Surrounding air rapidly moves into the low-pressure area to fill the space, causing wind speeds
to increase.
* The whole system of clouds and wind spins due to the trade winds and the earth’s rotation
(Coriolis effect).
* It can take hours or days to fully form a tropical storm. The eye is an area of calm winds, which
is surrounded by the ferocious eyewall of high winds and heavy rain.

Question 26

Hurricane Katrina Impacts

Answer 26

*Katrina was a category 4 storm.
* Storm surges reached over 6 metres in height.
*New Orleans was one of the worst affected areas because it lies below sea level and is protected by levees. These protect it from the Mississippi River and Lake Ponchartrain. The levee defences were unable to cope with the strength of Katrina, and water flooded into the city.
*Despite an evacuation order, many of the poorest people remained in the city.
*People sought refuge in the Superdome stadium. Conditions were unhygienic, and there was a shortage of food and water. Looting was commonplace throughout the city. Tension was high and many felt vulnerable and unsafe.
*1 million people were made homeless and about 1,200 people drowned in the floods.
*Oil facilities were damaged and as a result petrol prices rose in the UK and USA.

Question 27

Responses to the Katrina Hurricane

Answer 27

$50 billion in aid was given by the government.
The UK government sent food aid during the early stages of the recovery process.
The National Guard was mobilized to restore and maintain law and order in what became a hostile and unsafe living environment.

Question 28

Coastal Opportunities and Threats on the US Gulf Coast

Answer 28

Tourism
Commercial fishing is a multi-million-dollar industry in the Gulf of Mexico
Oil industry
Ports

Tropical storms
Oil spills
Climate change

Question 29

Coral reefs

Answer 29

Coral reefs are large underwater structures composed of skeletons of coral, which are marine invertebrate animals.
* The coral species that build coral reefs are known as hard corals because they extract calcium carbonate from seawater to create a hard, durable exoskeleton that protects their soft, sac-like bodies.
* Each individual coral is referred to as a polyp.
* New coral polyps live on the calcium carbonate exoskeletons of their ancestors, adding their own exoskeleton to the existing coral structure.
* As the centuries pass, the coral reef slowly grows, one tiny exoskeleton at a time, until they become massive features of the submarine environment.

Question 30

Where are coral reefs located

Answer 30

Coral reefs are located in tropical oceans near the equator.
* They are found 30 degrees north and south of the equator.
* The largest coral reef is the Great Barrier Reef in Australia.
* The second largest coral reef can be found off the coast of Belize, in Central America.
* Other reefs are found in Hawaii, the Red Sea, and other areas in tropical oceans.

Question 31

What conditions do coral reefs need

Answer 31

They are generally found between latitudes 30 degrees Celsius north and south of the equator because this is where ocean temperatures are warm enough for them to survive. They cannot survive in water below 18 degrees Celsius and the optimum temperature for growth is 22-25 degrees Celsius.
* They require shallow waters (of up to 60m) so that light can reach the reefs allowing algae that live on the coral to photosynthesize (the coral feeds on algae)
* They require clear water with small amounts of suspended material – as this allows sunlight to penetrate and reach the coral. Also, if sediment settles on polyps, they are unable to feed.
* Corals cannot grow much above tide level because they need oxygen and food brought by breaking waves. They can’t survive for long periods exposed above the water.
* Corals grow best in conditions of high salinity as freshwater kills coral. For this reason, breaks in reefs often occur at river mouths.

Question 32

Types of coral reef

Answer 32

Fringing reefs: the most common type, extend outward from a body of land with no water separating the reef from land.
Barrier reefs: are platforms separated from the shoreline by a channel or a lagoon.
Atolls: are coral islands that consist of a narrow, horseshoe-shaped reef with a shallow, central lagoon.

Question 33

How are Barrier reefs formed

Answer 33

Barrier reefs are created due to the sea level rising or the land sinking. The coral grows upwards so it can continue to photosynthesize, and this leaves a gap between the land and the reef.
The longest barrier reefs are found along the coasts of Belize and Australia.

Question 34

How are Atoll reefs formed

Answer 34

They often form around volcanic islands that have sunk due to the process of subduction.
Over 300 atolls are found throughout the South Pacific.

Question 35

The Great Barrier Reef

Answer 35

2012 km, at an offshore distance ranging from 10 to 100 miles.
Little annual variation in sea temperature, this has been important for the development of the reef as the optimum temperature for growth is 22-25 degrees Celsius.
400 types of coral, 1,500 species of fish and 4000 types of molluscs. It also holds great scientific interest as the habitat of species such as the dugong (sea cow) and the large green turtle, which are threatened with extinction.

Question 36

Mangroves

Answer 36

Mangroves are trees or shrubs which grow in tidal, tropical, and coastal swamps.
* They have tangled roots that grow above ground and form dense thickets.
* It is thought that they originate from Southeast Asia and then spread across the globe.
* Because they grow in the intertidal zone, they live in a constantly changing environment.

Question 37

Where are mangroves located

Answer 37

In sheltered tropical and subtropical coastal areas.
* In general, this is an area between latitudes of 30 degrees north and 30 degrees south of the equator.

Question 38

Conditions needed for mangroves development

Answer 38

Mangrove trees thrive in hot, muddy, salty conditions that would quickly kill most plants.
* Temperatures – Most mangroves grow in warm waters within 30 degrees latitude of the equator.
* They only grow in areas where the temperature remains above 20 degrees Celsius
* They grow in calm, shallow, sheltered areas with no strong waves or currents.
* They develop in areas where there is a large area between the high and low water mark.

Question 39

Characteristics of mangroves and adaptations

Answer 39

Mangrove swamps contain many different species of trees.
* Mangroves live in salty water as they are halophytes (salt tolerant plants).
* Mangroves are home to a diverse range of species including fish, birds, frogs, snakes, crocodiles, swamp rats, monkeys and tigers.
* Mangroves create a barrier to the shoreline and protect it from storms.
Salt-filtering roots that keep out much of the salt.
* Prop roots that help to hold the mangrove upright in the shifting sediments where land and water meet.
* Aerial roots that allow them to take in oxygen.
Mangroves also have salt-excreting leaves.

Question 40

The Sundarbans, Bangladesh mangroves

Answer 40

The Sundarbans is a natural region in southern Bangladesh and the extreme southern part of the Indian state of West Bengal in the vast river delta on the Bay of Bengal. It is the largest single block of tidal mangrove forest in the world.
The forest covers 10,000 square kilometres (3,900 sq mi) of which about 6,000 square kilometres (2,300 sq mi) are in Bangladesh.

Question 41

Sand dunes and conditions needed

Answer 41

Sand dunes are large heaps of sand that form on the dry backshore of a sandy beach.
For a sand dune to form, it needs:
*A large flat beach,
*A large supply of sand,
*A large tidal range, so there is time for the sand to dry,
*An onshore wind to move sand to the back of the
beach,
*An obstacle such as drift wood for the due to form
against.

Question 42

Formation of Sand dunes

Answer 42

-Embryo dunes form around deposited obstacles such as pieces of wood or rocks
-These develop and become stabilised by vegetation to form fore dunes and tall yellow dunes. Marram grass has adapted to windy, exposed conditions and has long roots to find water. these roots help bind the sand together and stabilise the dunes
-In time, rotting vegetation adds organic matter to the sand making it more fertile. A much greater range of plants colonises these”back dunes”.
-Wind can form depressions in the sand called dune slacks, in which ponds may form.

Question 43

Characteristics of Sand dunes

Answer 43

-Embryo dunes are only a few metres high whereas mature dunes may be up to 15 metres high.
-Size of sand dunes increases inland as long-rooted marram grass binds the sand together. Its long roots help build up the height of the dunes.
-Dunes closest to the beach have a yellow sandy colour and not much vegetation, whereas dunes at the back are grey and less sand-like.
-Inland the dunes become increasingly colonised by vegetation.
-Each line of dunes is separated by a trough called a slack. Slacks are formed by the removal of sediment from the leeward base of one line of dunes and up the windward side of the next line.
-Sometimes slacks are eroded so much that they reach down to the water table, resulting in the formation of ponds.