dynamic planet

Restless Earth, Climate and change, Battle of the Biosphere, Water World, Coasts, Oceans on the Edge 

HideShow resource information

Restless Earth

Oceanic crust- found under the oceans and is thin and but dense as it is made out of basalt with no crystals in it as it is cooled very quickly Continental - is land and is think but less dense as it as made out of granite which contains crystals as it cools very slowly The lithosphere is split into tectonic plates These move slowly on top of a layer called the asthenosphere  meteorites give us a clue to what the core is like  how do we know the earth is hot?  lava from volcanoes  hot springs How are we damaging each of the spheres? Atmosphere -releasing CO2 into. Hydrosphere -using too much water in some areas Biosphere - deforestation - animals extinct. Geosphere - using up fossil fuels Geothermal heat… - Heat from the inside of the earth. Produced by the radioactive decay of uranium etc in the core  and mantle.  - As heat rises from the core it creates convection currents in the liquid outer core and mantle. These convection currents move the tectonic plates on top of them. How convection currents drive plate tectonic movements • Convection currents occurred in the mantle and these are driven by the heat of the core.  This heat is created due to both the pressure of the overlying  material but also produced by the radioactive decay of uranium etc in the   core and mantle. • As heat rises from the core it creates convection currents in the liquid outer core and mantle. These convection currents move the tectonic plates on top of them. The continents were once all joined together – Pangea. How do we know this? Identical fossils and rocks have been found in western -Africa and Eastern South America for example. Today the lithosphere is split into 15 tectonic plates. Where 2 plates meet together = plate boundary Constructive plate boundary… - Where two oceanic plates are moving apart from each other. - New oceanic crust is forming constantly in the gap created. - The magma is injected between the two plates. As it cools it forms new oceanic crust. -The magma is runny. Shallow sided volcanoes form. HAZARDS: - Small earthquakes are formed by friction as the plates tear apart. - Volcanoes that are not very explosive/dangerous.       Examples are Iceland – the Mid Atlantic Ridge Destructive plate boundary… - Where an oceanic plate meets a continental plate. They are moving towards each other. -The denser oceanic plate is subducted beneath the less dense continental plate. HAZARDS: -very destructive earthquakes -tsunami -very explosive, destructive volcanoes which cool to be steep sided. Examples are Andes mountains, Peru, Chile. Conservative plate boundary… - Formed where two plates are sliding past each other. Collision Zone A type of destructive boundary where two continental plates move  towards each other. As they meet they push upwards forming mountain ranges e.g. Himalayas. Convection currents from the mantle bring magma towards the surface. Magma is forced between the plates, cools and forms new oceanic crust.          HAZARDS: - destructive earthquakes - landslides   - volcanoes are rare

1 of 9

Restless Earth 2

COLLISION Two plates moving together (continental and continental) Indian and the Eurasian Plate - formed the Himalayas Volcanic Explosivity Index (VEI)- Measures the destructive power of a volcano on a scale from 1 to 8 Shield volcanoes Shield volcanoes are usually found at constructive or tensional boundaries. They are low, with gently sloping sides. They are formed by eruptions of thin, runny lava. Eruptions tend to be frequent but relatively gentle. Composite volcanoes                           Composite volcanoes are made up of alternating layers of lava and ash (other volcanoes just consist of lava). They are usually found at destructive or compressional boundaries. The eruptions from these volcanoes may be a pyroclastic flow rather than a lava flow. A pyroclastic flow is a mixture of hot steam, ash, rock and dust. A pyroclastic flow can roll down the sides of a volcano at very high speeds and with temperatures of over 400°C. Why are people in developing countries at greater risk from tectonic hazards than people in developed countries?  More live in risky conditions – no where else for them to live. Can’t afford safe, well built houses- they collapse easily Don’t have insurance Governments don’t have the money to provide aid. Poor communications – no warning or evacuation AID AND RELIEF EFFORT ( help given by organisations/countries to help those facing an emergency). -United Nations sent 260 tonnes of food. -UK TV appeal - Governments around the world gave $35 million - Emergency measles vaccinations by the World Health Organisation. - most fled with nothing -it was months before they could start rebuilding. EARTHQUAKES can’t be predicted. Underground plates try to push past each other– builds up pressure – suddenly released along faults (cracks in the crust). Energy is sent out in all directions.  Magnitude = power of the earthquake Seismometer measures the power on the richter scale How earthquakes and volcanoes can be planned for and predicted Being Prepared: - Emergency plans - Warning systems - Training of people - Evacuation plans Reducing the impact: 1.Improving building design Different types of hazard response, both short and long term Short term: - This includes mainly immediate aid to keep people alive e.g. tents, blankets and food Long term:  - this looks to improve the preparedness of the people and reduce the impact of any future events

2 of 9

Climate And Change

WEATHER = short term, day to day changes in the atmosphere. CLIMATE = the average weather conditions over 30 years. Graph shows that average temperatures in the past 2000 years have varied between 1-1.5°c colder or warmer than average temperatures today.   INTERGLACIALS = warm periods GLACIALS = cold periods- ice ages -ice sheets 400-3000m thick extended across the northern hemisphere. How do we know climate was different in the past? • Fossils of animals and plants that no longer live in the UK. • Landforms left by glaciers • Samples from ice sheets in Antarctica. Ice sheets are made up of layers of ice, a layer for each year. Trapped in the ice sheets are air bubbles. Climatologists study the CO2 levels to reconstruct past climates. How do we know climate has changed in the more recent past? • Old photos, paintings • Diaries • Newspapers • Recorded dates of blossom and migration of birds. The theories used to explain why climate has changed in the past (Natural events).... 1. ERUPTION THEORY – very large and explosive volcanic eruptions change earth’s climate. Ash and gas spread around the stratosphere and stop sunlight reaching the earth’s surface the earth. Example is Mt Pinatubo, 1991, Philippines – reduced global sunlight by 10% and cooled the earth 0.5 degrees for a year. 2. SUNSPOT THEORY – black areas on the sun’s surface. Some times there are more then they disappear. Spots mean greater activity and more solar energy being sent towards the earth warmer. 3. ORBITAL THEORY/MILANKOVITH CYCLES – Changes in the way the earth orbits the sun from circular to ellipse alters the amount of sunlight the earth receives. How were ecosystems affected by climate change in the past? -The dinosaur extinction was possibly caused by a massive asteroid hitting Mexico and a huge volcano in India combining -dust, ash, gas into the stratosphere - blocks the sun-cools the climate - plants don’t grow -dinosaurs have no food……..knock on effect through the food chain. -Megafauna extinction – big animals like the woolly mammoth. The climate was warming so they had to find new areas to live where the climate suited them. This disrupted food chains. Humans also hunted them to extinction. How is our atmosphere being changed by human activity? Greenhouse gases (CO2 from the burning of fossil fuels, deforestation, Methane from paddy fields and cattle, Nitrous oxide from aircraft engines and fertilisers) trap heat from leaving the atmosphere and re-radiate that heat back down to earth. The greater the concentration of greenhouse gases, the more heat is trapped and the warmer earth becomes.We need the NATURAL greenhouse effect – it makes the planet 16 degrees warmer. Without it the earth would be too cold for us to survive.The extra greenhouse gases produces by humans - burning fossil fuels - power stations, transport, industry, homes. What can we do? - Decrease fossil fuel use. -Switch to ‘green energy’ – wind, solar, tidal. - Recycle more - Use cars less and public transport more. 1997 Kyoto Protocol  = international agreement to cut CO2 emissions. Some countries e.g. UK have cut emissions, others e.g. China haven’t. We need ALL countries to sign up.

3 of 9

Battle Of The Biosphere

Tropical Rainforests: Mostly in a band either side of the Equator as the sun’s rays are  concentrated here and there is heavy rainfall. Deserts – found close to the Tropic lines, sun’s rays are concentrated but the air is dry Deciduous – Grows in higher latitudes e.g. UK where the sun’s rays are less concentrated and cooler winter temperatures encourage trees to loose their leaves. Coniferous – found 60° north where temperatures are so cold that trees have evolved pine needles to reduce moisture loss. Tundra – found at the Arctic Circle where the sun’s rays have little strength and temperatures remain mostly below freezing. BIOME = WORLD SCALE ECOSYSTEM The world has 9 major biomes – determined by climate: -Temperature – length of the growing season -Precipitation - Sunshine hours – precipitation - Humidity Why does climate vary around the world? LATITUDE: At the equator the sun’s rays hit the earth at right angles, therefore concentrating the insolation and making it very hot. At the poles the rays hit at a greater angle, so the insolation is spread out over a greater area and is much less concentrated. At the equator the air is always rising = LOW pressure = clouds and rain = rainforests .At 30 degrees north and south of the equator the air is always sinking = HIGH pressure = no clouds and no rain = deserts. ALTITUDE: (height of the land) – as height increases so the climate gets increasingly cold and wet. Temperature decreases 1 degree for every 100m of height. THE SEA: keeps places near the coast cooler in summer and warmer in winter (as water heats up and cools down more slowly than the land) this is called continentally. PREVAILING WINDS: If the most common winds come from across the land, the climate = dry. If across the sea, the climate – wet. From the poles = cold, from the equator = warm. Goods and services  GOODS = things of value to us SERVICES = things that satisfy our needs How is the biosphere being degraded by human actions? Every year the ‘red list’ of endangered animals is produced. Increasingly, habitats are being damaged and destroyed  this leads to increased threat of species survival. Immediate causes = logging, overfishing, pollution Root causes = increasing populations, economic development e.g. China, India  now = more money and therefore consuming more food and fuel etc. Certain species and places are particularly under threat. There are 25 ‘hotspots’ where there is greatest concentration of biodiversity (number of plants and animals).

4 of 9

Water World

THE HYDROLOGICAL CYCLE The hydrological cycle is a CLOSED SYSTEM – A finite amount of water going round and round. None is added or lost. STORES: rocks (can be stored for 100’s yrs), soil, lakes, oceans (97% water stored BUT too salty to use) glaciers. The soil, lakes and rocks hold relatively small amounts of fresh water – but are in high demand as sources of water.. TRANSFERS/FLOWS: Surface runoff, throughflow, groundwater flow, infiltration, precipitation. Demand increases as population increases. - Increased demand from agriculture – irrigating their crops uses huge amounts of water. - Supplies are increasingly unpredictable - Possibility of water wars – Middle East – fighting over water. Economic development – China, India – increased demand for water - Rising living standards = use more water e.g. showers, washing machines etc Only ½ freshwater runoff (BLUE WATER) is used. Most is inaccessible. WATER STRESS = when demand is greater than supply or when it is not of good enough quality to use. Turkmenistan and Uzbekistan are the most water stressed countries in the world - they use huge quantities for irrigating cotton crops. SW USA, Central Asia = PHYSICAL WATER SCARCITY – Demand > availability Sub Saharan Africa = ECONOMIC WATER SCARCITY – supply available but people can’t afford to exploit them. Lack of money to build storage facilities or distribute water. Water quality… People can suffer economic water stress if water isn’t safe. Pollution can be: domestic, industrial, agricultural, transport related.

5 of 9

Coasts

THE COASTAL ZONE = the zone between the land and sea. Coasts are always changing. Advantages of living by the coast:  Fish  Good agricultural land found next to the coast  Access for trade  Tourism opportunities  Recreation EROSION: The process of wearing the cliffs away. HYDRAULIC ACTION The power of water/waves forced into cracks and forcing the rocks apart  ABRASION Rocks are hurled against the cliff. They scour away  like sandpaper.  ATTRITION Two rocks crash into each other and break down into smaller pieces.  Some rocks are very resistant to erosion e.g. granite. Some rocks are least resistant e.g. clays and will erode quickly wave cut platform 1. The sea attacks the base of the cliff forming a wave-cut notch. 2. The notch increases in size causing the cliff to collapse. 3. The process repeats and the cliff continues to retreat. 4. A wave cut platform is left at the bottom. Exposed at low tides. Concordant and Discordant coastlines: Geology is the study of the types of rocks that make up the Earth's crust. Coastlines where the geology alternates between strata (or bands) of hard rock and soft rock are called discordant coastlines. A concordant coastline has the same type of rock along its length. Concordant coastlines tend to have fewer bays and headlands. ROCK STRUCTURE = the way rock types are arranged. Usually in layers (strata) Waves… The wind blows across the sea. Friction between the wind and water creates waves. The size of the waves depends on:  The strength of the wind  How long the wind blows for  The length of water the wind lows over (the fetch). This is why Cornwall has the biggest waves in England. How waves break… 1. Out at sea the wind creates a wave shape. 2. Within a wave each water particle moves in a circular movement and returns to the start. It is only energy and not the water itself that is moving forward. 3. When the wave reaches shallow water the wave is distorted from a circular shape to an ellipse shape until it becomes so top heavy that it ‘breaks’. 4. it is now not only energy but also water that moves forwards. The waves come up the beach (swash) in the direction of the prevailing wind. The waves go back down the beach (backwash) at right angles due to gravity Summer waves = constructive waves: - small - long wavelengths - low amplitudes - strong swash so transport sand up the beach and deposit it – builds up the beach. Winter waves = destructive waves: - taller (larger amplitude) - closer together (shorter wavelength) - plunging waves = dangerous as are so quick the backwash has to flow under the incoming wave = rip current = dangerous to swimmers as can drag them out to sea. - strong backwash – erodes sand from the beach and carries it out to sea where it is deposited. - Steep beach is formed Coastal landforms of deposition… SEDIMENT = tiny clay particles, sand, silt, pebbles, boulders The particles of sand or shingle are transported along the beach in a zig zag movement, carried by the swash and backwash. As the prevailing wind is usually in the same direction so LSD usually is too Sand Dunes… Strong onshore winds blow the sand inshore Spits… - At a corner in the coastline LSD continues to deposit out to sea forming a neck of sand and shingle. - The end is curved round by the wind and waves. - Salt marsh forms in the shelter of the spit. SEA WALLS  reflect the waves back out to sea  Costly  Makes it hard to access the beach  The wall itself erodes = high maintenance costs. GROYNES  Trap and stop the longshore drift from moving along. Builds up a nice big sandy beach. This is the best form of protection against erosion – the wave moves around every grain of sand, taking lots of energy out of the wave (energy is dissipated).  Good for tourism  Has a negative impact down the coast which is starved of sediment –here the beach becomes smaller and offers less protection so erosion rates increase greatly. This = conflict. ROCK ARMOUR/RIP RAP  Big boulders placed at the base of the cliff – dissipate the energy of the waves.  Looks natural.  Makes access to the beach difficult.  Can be hard to transport the boulders into position.

6 of 9

Oceans On the Edge

Global patterns...  2008 oceans environmental damage map  Enclosed seas most at risk eg Mediterranean, North Sea  Polar areas least damaged  Dead zones (collapsed ecosystems) increasing NAMED EXAMPLE: coral reefs  Shallow water (<25m) for sunlight.  Tropical salt water temperatures 24-26°c  Avoid river mouths due to sediment     Scattered cattle farms  A few dirt tracks Why Are Coral Reefs Valuable? Exploitation of Fish-25% all known marine species – food for local communities. 25% total commercial fish catch comes from coral reefs Shoreline Protection-Protect against tsunami and wave erosion,. Grow with rising sea levels so protect against climate change. Aquarium Trade Supplies for aquarium trade.-Tourism Reefs are magnet for tourists, more than 50% income for Caribbean countries from reef tourism. Education and Research-Easy to access and learn. Other uses Medicine source, jewellery, lime for cement.  Threats To Coral Reefs  Bleaching-El Nino-  Blast fishing- Overfishing eg Parrot fish-Diseases-Siltation- Hurricanes-Coral mining-Tourism- pollution- Predators-Unsustainable Use of Marine Ecosystems-Habitat destruction- Pollution Krill are keystone species  Krill population declined 80% since 1980s  Now high demand in fish farms and omega 3 supplements – under threat – suction farming Nutrient Overloading  Also called eutrophication  Nutrient cycles disrupted by pollution  Polluted dead zones greatest threats to world oceans  Dead zones – ocean areas critically low in 02 – can’t support life  Now commonplace offshore from developed/developing countries  Climate change effect – more storms wash nitrates and phosphates from land to ocean

7 of 9

Oceans On the Edge

Global patterns...  2008 oceans environmental damage map  Enclosed seas most at risk eg Mediterranean, North Sea  Polar areas least damaged  Dead zones (collapsed ecosystems) increasing NAMED EXAMPLE: coral reefs  Shallow water (<25m) for sunlight.  Tropical salt water temperatures 24-26°c  Avoid river mouths due to sediment     Scattered cattle farms  A few dirt tracks Why Are Coral Reefs Valuable? Exploitation of Fish-25% all known marine species – food for local communities. 25% total commercial fish catch comes from coral reefs Shoreline Protection-Protect against tsunami and wave erosion,. Grow with rising sea levels so protect against climate change. Aquarium Trade Supplies for aquarium trade.-Tourism Reefs are magnet for tourists, more than 50% income for Caribbean countries from reef tourism. Education and Research-Easy to access and learn. Other uses Medicine source, jewellery, lime for cement.  Threats To Coral Reefs  Bleaching-El Nino-  Blast fishing- Overfishing eg Parrot fish-Diseases-Siltation- Hurricanes-Coral mining-Tourism- pollution- Predators-Unsustainable Use of Marine Ecosystems-Habitat destruction- Pollution Krill are keystone species  Krill population declined 80% since 1980s  Now high demand in fish farms and omega 3 supplements – under threat – suction farming Nutrient Overloading  Also called eutrophication  Nutrient cycles disrupted by pollution  Polluted dead zones greatest threats to world oceans  Dead zones – ocean areas critically low in 02 – can’t support life  Now commonplace offshore from developed/developing countries  Climate change effect – more storms wash nitrates and phosphates from land to ocean

8 of 9

Oceans On the Edge

Global patterns...  2008 oceans environmental damage map  Enclosed seas most at risk eg Mediterranean, North Sea  Polar areas least damaged  Dead zones (collapsed ecosystems) increasing NAMED EXAMPLE: coral reefs  Shallow water (<25m) for sunlight.  Tropical salt water temperatures 24-26°c  Avoid river mouths due to sediment     Scattered cattle farms  A few dirt tracks Why Are Coral Reefs Valuable? Exploitation of Fish-25% all known marine species – food for local communities. 25% total commercial fish catch comes from coral reefs Shoreline Protection-Protect against tsunami and wave erosion,. Grow with rising sea levels so protect against climate change. Aquarium Trade Supplies for aquarium trade.-Tourism Reefs are magnet for tourists, more than 50% income for Caribbean countries from reef tourism. Education and Research-Easy to access and learn. Other uses Medicine source, jewellery, lime for cement.  Threats To Coral Reefs  Bleaching-El Nino-  Blast fishing- Overfishing eg Parrot fish-Diseases-Siltation- Hurricanes-Coral mining-Tourism- pollution- Predators-Unsustainable Use of Marine Ecosystems-Habitat destruction- Pollution Krill are keystone species  Krill population declined 80% since 1980s  Now high demand in fish farms and omega 3 supplements – under threat – suction farming Nutrient Overloading  Also called eutrophication  Nutrient cycles disrupted by pollution  Polluted dead zones greatest threats to world oceans  Dead zones – ocean areas critically low in 02 – can’t support life  Now commonplace offshore from developed/developing countries  Climate change effect – more storms wash nitrates and phosphates from land to ocean

9 of 9

Comments

No comments have yet been made

Similar Geography resources:

See all Geography resources »See all resources »