PMT Coastal Environments Flashcards

Question

Oxidation

Answer 1

When minerals become exposed to the air through cracks and fissures the mineral will become oxidised which will increase its volume causing the rock to crumble. The most common oxidation within rocks is iron minerals becoming iron oxide turning the rock rusty orange after being exposed to the air

Answer 2

When rock minerals such as rock salt are dissolved

Answer 3

The breakdown of rocks by organic activity

Answer 4

Roots of plants grow into the cracks of rocks which exerts pressure eventually splitting the rocks

Answer 5

Some birds such as puffins dig burrows into cliffs weakening them and making erosion more likely

Answer 6

Many species of clams secrete chemicals that dissolve rocks and piddocks may burrow into the rock face

Answer 7

Some seaweeds contain pockets of sulphuric acid which if hit against a rock or cliff face the acid will dissolve some of the rocks minerals

Answer 8

Water the flows through decaying vegetation and then over coastal areas will be acidic causing chemical weathering

Answer 9

The movement of material down a slope under the influence of gravity categorised as heaves, flows, slides and falls

Answer 10

Cliff and slope angle Rock type Rock structure Vegetation Saturation of ground Presence of weathering

Answer 11

The slowest but most continuous form of mass movement involving the movement of soil particles downhill. Particles rise and fall due to wetting and freezing and this causes the soil to move down the slope. It leads to the formation of shallow terraces

Answer 12

An increase int he water content of soil can reduce friction leading to earth and mud to flow over underlying bedrock or slippery materials such as clay. Water can get trapped within the rock increasing pore water pressure which forces rock particles apart and therefore weakens the slope. Mudflows represent a serious threat to life as they can be very fast flowing

Answer 13

Occur on sloped cliffs when exposed to mechanical weathering though mostly occurs on vertical cliff faces and can be triggered by earthquakes. It leads to scree building up a the base of the slope

Answer 14

Heavy rainfall leads to water between joints and bedding planes in cliffs which are parallel to the cliff face which can reduce friction and lead to a landslide. It occurs when a block of intact rock moves down the cliff face very quickly along a flat slope

Answer 15

Large, heavy sediment rolls along the sea bed pushed by currents

Answer 16

Smaller sediment bounces along the sea bed being pushed by currents. The sediment is too heavy to be picked up by the flow of the water

Answer 17

Small sediment is carried within the flow of the water. Greater velocities of water are able to suspend larger and heavier pieces of sediment

Answer 18

Dissolved material is carried within the water potentially in a chemical form

Answer 19

Occurs when sediment becomes too heavy for the water to carry or if the wave loses energy. Deposition tends to be a gradual and continuous process so a wave won't release all its sediment at the same time. This is why beaches are often either sandy or rocky and these areas are very distinct on the same beach

Answer 20

High energy coastlines continue to transport smaller sediment so larger rocks and shingle are deposited in these environments. Low energy coastlines have much smaller sediment which is only deposited in these areas where there is a much lower water velocity

Answer 21

The waters velocity decreases so sediment begins to be deposited

Answer 22

This is an important process in salt and tidal marshes. Clay particles clump together due to chemical attraction and then sink due to their high density

Answer 23

Most of the sediment in the coastal zone is a result of an input from rivers especially in high rainfall environments where significant river erosion occurs. Sediment may be deposited in estuaries which are brackish areas where rivers flow into the sea. They are important wildlife habitats. The sediment is then transported throughout the coastal system by waves, tides and currents

Answer 24

Very important in areas with unconsolidated cliffs that are eroded easily. In some areas coastlines can retreat by up to 10m per year providing a significant sediment input. Most erosion occurs during the winter months due to more frequent storms

Answer 25

Wind is a coastal energy source and can cause sand to be blown along or up a beach. Sediment transport by winds may occur where there are sand dunes or in glacial and desert environments which provide sediment inputs

Answer 26

In some coastal systems glaciers flow directly into the ocean depositing sediment that was stored in the ice. This occurs when glaciers calve a process where ice breaks off the glacier

Answer 27

Sediment is transferred to the coastal zone when waves, tides and currents erode offshore sediment sinks such as offshore bars. The sediment is transported onto the beach helping to build up the beach. Storm surges or tsunami waves may also transfer sediment into the coastal zone

Answer 28

Waves hit the beach at an angle determined by the direction of the prevailing wind. The waves push sediment in this direction and up the beach in the swash. Due to gravity the wave then carries sediment back down the beach in the backwash. This moves sediment along the beach over time

Answer 29

Coasts can be split into sections called sediment cells which are often bordered by prominent headlands. Within these sections the movements of sediment is almost contained and the flows of sediment act in dynamic equilibrium. Sediment cells are split up into smaller cells called sub-cells

Answer 30

The maintenance of a balance in a natural system despite it being in a constant state of change. The system has a tendency to counteract any changes imposed on the system in order to keep this balance which is achieved by inputs and outputs constantly changing to maintain the balance. In a sediment cell it is where input and output of sediment are in a constant state of change but remain in balance

Answer 31

Most common where the rock is strong and fairly resistant to erosion. Sedimentary rocks that have vertical strata are also more resistant to erosion creating steep cliffs. An absence of a beach, long fetch and high energy waves also promote steep cliff development. Most commonly found in high energy environments

Answer 32

Most commonly found in areas with weaker rocks which are less resistant to erosion and are prone to slumping. Low energy waves and a short fetch will lead to the formation of a scree mound at the base of the cliff reducing the overall cliff angle. A large beach would also reduce wave energy and prevent the development of steep cliffs by reducing erosion rates. Most commonly found in low energy environments

Answer 33

Dependent on the relative important of marine factors and terrestrial factors. The cliffs most likely to retreat are those that are made of unconsolidated tock and sands

Answer 34

When waves erode a cliff the erosion is mostly concentrated around the high tide line. The main processes of hydraulic action and corrasion create a wave cut notch. As the notch becomes deeper the cliff face becomes unstable and falls under its own weight through mass movement. This leaves behind a platform of the unaffected cliff base beneath the wave cut notch. Over time the same processes repeat leading to a wave cut platform to be formed which is normally exposed at high tide

Answer 35

Waves enter faults and cracks in the headland and erode the cracks through the processes of hydraulic action and abrasion. The cave will widen due to both marine erosion and sun aerial processes eroding through to the other side of the headland creating and arch. The arch continues to widen until it is unstable to support itself falling under its own weight through mass movement leaving a stack as one side of the arch becomes detached from the mainland. As marine erosion continues attacking the base of the stack eventually the stack will collapse into a stump

Answer 36

A depositional landform that stretches from roughly the low tide to the high tide line. Beaches are created when sediment is deposited near the coastline when waves lose their energy. Larger sediment is found toward the top of the beach where it has been left from winter storms. The backwash is often weaker than the swash as the water quickly percolates into the sand. As the backwash isn't as powerful the larger sediment remains at the top of the beach. Scree near the cliffs as a result of mass movement processes and weathering means that angularity increases towards the cliff

Answer 37

Wave crests approach parallel to the coast so there is limited longshore drift. Sediment doesn't travel far along the beach. Wave refraction may reduce the speed of high energy waves leading to the formation of a shingle beach with larger sediment

Answer 38

Waves approach at a significant angle so longshore drift causes the sediment to travel far along the beach which may lead to the formation of a spit at the end of a beach. Generally larger sediment is found at the start of the beach and weathered sediment moves further down the beach through longshore drift becoming smaller as it does so the end of the beach is likely to contain smaller sediment

Answer 39

A long narrow strip of land which is formed when longshore drift causes the beach to extend out to sea usually due to a change in direction of the coastline. The sediment projection can create a salt marsh due to the sheltered, saline environment where water flow speed is lower allowing deposition of finer sediments to occur. The length depends on any changing currents or rivers which will prevent sediment from being deposited. This means a spit can never extend across an estuary. A change in wind direction or wave direction can cause the end of the spit to curve. Over time the recurved end may be abandoned and a new spit will form on the old recurved end. This creates a spit with multiple recurved ends called a compound spit

Answer 40

An offshore region where sand is deposited as the waves don't have enough energy to carry the sediment to shore. They can be formed when the wave breaks early instantly depositing its sediment as a loose sediment offshore bar. They may also be formed as a result of backwash from destructive waves removing sediment from a beach. They may absorb wave energy reducing erosion in some areas

Answer 41

A spit that connects the mainland to an offshore island. Tombolos are formed due to wave refraction off the coastal island reducing wave velocity leading to deposition of sediments. They may be covered at high tide of they are low lying

Answer 42

Occurs when a beach or spit extends across a back to join two headlands. This traps water behind it leading to the formation of a brackish lagoon which is separated from the sea. As well as forming from present day processes some barrier beaches may have formed due to rising sea levels after the last glacial period when meltwater from glaciers deposited sediment in the coastal zone. If a barrier beach becomes separated from the mainland it becomes a barrier island

Answer 43

Occur when prevailing winds blow sediment to the back of the beach and therefore the formation of dunes requires large quantities of sand and a large tidal range. This allows the sand to dry so that it is light enough to be picked up and carried by the wind to the back of the beach. Frequent and strong onshore winds are also necessary. The dunes develop as a process of vegetation succession

Answer 44

Pioneer species such as sea rocket are resistant and able to survive in the salty sand with its roots helping to bind the dunes together. Decaying organic matter adds nutrients and humus to the soil allowing marram grass to grow. Larger plants are able to colonise the area and the climatic climax occurs when trees are able to colonise the area

Answer 45

Upper beach area where sand starts to accumulate around a small obstable

Answer 46

As more sand accumulates and the dune grows. Vegetation may develop on the upper and back dune surfaces which stabilises the dune. This is the tallest of the dune succession

Answer 47

Sand develops into soil with lots of moisture and nutrients as vegetation dies enabling more varied plant growth

Answer 48

The water table rises closer to the surface or water is trapped between hollows between dunes during storms allowing the development of moisture loving plants

Answer 49

Sandy soils develop as there is a greater nutrient content allowing for less brackish plants to thrive. Trees will also grow with the coastal woodland becoming a natural windbreak to the mainland behind

Answer 50

In sheltered bay or behind spits, slat and minerals will build up. Vegetation may establish further stabilising the salt marsh. They can stabilise through vegetation succession

Answer 51

Algal sage Pioneer stage Establishment stage Stabilisation Climax vegetation

Answer 52

Mangroves are trees that are adapted to grow in saline low oxygen conditions. They develop in coastal swamps in tropical regions meaning the environment around them is constantly changing with the tides. Mangroves can stabilise shorelines with roots and protect areas from erosion as well as providing an environment for wildlife

Answer 53

An estuary is the point where a river meets the ocean. Deposition occurs in river estuaries due to the change in water velocity from a river to an ocean. When the flow of water from the river meets with the incoming tides and waves from the sea the water flow virtually ceases so the water can no longer carry its sediment in suspension. As most of the sediment is small and fine it leads to a build up of mud which builds up until it is above the water level. Deposition also occurs as a result of flocculation. Pioneer plants colonise this area leading to more sediment becoming trapped. This colonises the transition zone between high and low tide. Mudflats and salt marshes may develop as a result of sedimentation

Answer 54

Sea levels change in shoer term periods such as day to day or minute to minute due to factors such as tide and low tide, wind strength and changes in wind direction or changes i atmospheric pressure. Sea level change also occurs over long term periods leading to the formation of various coastal landforms as a result of isostatic and eustatic change

Answer 55

Occurs when the land rises or falls relative to the sea and is a localised change. Often a result of isostatic subsidence. The melting of glaciers after the last ice age has led to isostatic recovery causing the coastline to rebound and rise again in the areas that were covered by ice. Tectonic activity may cause land subsidence therefore causing isostatic sea level change

Answer 56

Affects sea level across the whole planet. May be due to thermal expansion/contraction or changes in glacial processes. Thermal expansion is the process of water expanding when it gets warmer so the volume of water increases leading to rising sea levels

Answer 57

Where the land has been raised in relation to the coastline landforms such as arches, stacks and stumps may be preserved. Raised beaches are common before cliffs which are also raise with wave cut notches and similar features proof of historical marine erosion

Answer 58

Formed when rising sea levels flood narrow winding inlets and river valleys. They are deeper at the mouth of the inlet with the water depth decreasing further inland

Answer 59

Landforms of submergence occur when the sea level rises or the coastline sinks in relation to the sea

Answer 60

Formed when rising sea levels flood deep glacial valleys to create natural inlets and harbours. Are deeper in the middle section than they are at the mouth with the shallower section identifying where the glacier left the valley

Answer 61

Occurs when valleys running parallel to the coast become flooded as a result of sea level change. This leaves a series of narrow, long and rugged island

Answer 62

Underwater ecosystems characterised by large amounts of coral held together by calcium carbonate. These reefs create environments suitable for abundances of wildlife to live in

Answer 63

Only survive in saltwater Thrive in warm oceans (23-25C) so located in the tropics Algae lives inside corals and this needs light to photosynthesise. Corals rely on the algae for oxygen so also rely on light to survive and only grow in shallower water where light can still reach them Need a certain amount of oxygen so localised wave movements can encourage growth Sediments and pollutants can block sunlight, poison coral and disrupt feeding

Answer 64

Attached to the shoreline or run closely parallel to the shoreline. They are the most common type of coral reef. Do not have to grow directly attached to the shore and may be separated by a shallow back reef. When there is a deep, wide lagoon between the reef and shore it is then a barrier reef

Answer 65

A reef that is completely separate from a shore by a lagoon. The lagoons can be 30-70m deep and kilometers wide. Can also run parallel to the coastline but are separated by much deeper and wider lagoons

Answer 66

Circular coral reefs with a lagoon in the middle. They form from a fringing reef surrounding a volcanic island. As sea levels rise or as the volcanic island sinks back into the ocean the reef continues to grow. This leaves a ring of coral that once surrounded the island with a shallow lagoon in the middle

Answer 67

CO2 from the atmosphere is absorbed into the ocean leading to ocean acidification. This breaks down the calcium carbonate and therefore comprises the structural integrity of coral reefs. Sediment and land based pollutants can wash into the ocean making the water murky and therefore blocking light which affects the photosynthesis of algae. Pollutants may be toxic or dangerous to corals

Answer 68

Coral bleaching occurs when algae leaves corals making corals more susceptible to disease. Coral bleaching occurs when ocean temperatures become too high for algae to survive in corals. More diseases and invasive species may thrive in warmer waters potentially harming corals and the coral reef ecosystem. More frequent, strong storms can disrupt and destroy coral reefs. Changing ocean currents can disrupt food chains and wave action that coral reefs rely on

Answer 69

If sea levels rise faster than the upward growth of coral corals may be too deep to receive sufficient sunlight. The rise in sea levels can cause increased coastal erosion in areas. More sediment is transported into the oceans which can lead to sedimentation in coral reefs blocking sunlight and disrupting the ecosystem. This is a particular threat to fringing reefs as they are so close to the shoreline

Answer 70

Boating can physically disrupt coral reefs especially if an anchor is dropped onto a reef. Large boats may bulldoze through areas of coral and destroy them. Destructive fishing practices can damage or destroy coral reefs. Bottom trawling is a method of fishing where a large net is dragged on the sea floor and this particular fishing method is very disruptive. Unsustainable tourism can cause damage especially if people touch the reefs

Answer 71

Threats to coral reefs can be reduced by reducing the activities that take place there. Banning fishing, tourist activities and diving is the most successful way or reducing the physical damage that these cause. Temporary closures of coral reef areas can be a good way of allowing reefs to recuperate after times of stress for coral reefs

Answer 72

Invasive species can be harmful affecting the coral directly and affecting the ecosystem that the coral depends on. Management strategies are in place to ensure these invasive species do not enter the ecosystems and in the event they do they can be controlled as to limit the effects they have. Schemes to remove predators can also help to manage coral reefs.

Answer 73

Large scale coral reef damage is largely caused by CO2 emissions. Reducing emissions on a global scale is necessary to reduce the problems associated with CO2 emissions. Government strategies, greener energy sources and a reduced reliance on fossil fuels can all contribute to lower CO2 emissions helping coral reefs in the long term

Answer 74

Educating those who are around coral reefs on how to interact with this environment can be a successful way of managing coral reefs