National Year 12 Geography
Chapters: 6
1. 3.1.1 Water and carbon cycles (compulsory)
Water and carbon cycles as natural systems · The water cycle · The carbon cycle · Water, carbon, climate and life on Earth · Quantitative and qualitative skills · Case studies
- The Carbon Cycle: Where Carbon Is Stored and How It Moves – Carbon moves between the air, living things, soil, oceans and rocks. These places are called stores (or sinks and sources), and the movements are called flows (fluxes). Photosynthesis takes carbon dioxide out of the air; respiration, decomposition and burning put it back. The ocean takes in and gives out huge amounts. Over millions of years carbon is locked into rocks and fossil fuels, and volcanoes and weathering slowly return it. People now burn fossil fuels and clear forests, adding carbon faster than natural sinks can take it up, so the CO₂ in the air rises and the Earth warms.
- The Water Cycle as a System – Earth's water moves between stores (oceans, ice, groundwater, rivers, lakes, soil, air and living things) through flows such as evaporation, condensation, precipitation, infiltration and runoff. Globally it is a closed system: the total amount stays the same. A drainage basin is an open system: rain comes in, water is stored, and it leaves by river runoff and evapotranspiration. The water balance P = Q + E ± ΔS tracks this. A storm hydrograph shows how quickly a river answers rain; its peak and lag time depend on rock, soil, slope, plants and land use. Seasons, storms, deforestation, farming, towns and water abstraction all change the cycle.
2. 3.1.2 Hot desert systems and landscapes (Section B option: choose one of deserts, coasts, glacial)
Deserts as natural systems · Systems and processes · Arid landscape development in contrasting settings · Desertification · Quantitative and qualitative skills · Case studies
- Hot Deserts: Climate, Life, People and Desertification – Hot deserts are places that get less than about 250 mm of rain a year and are hot for most of the year. They lie mostly in two belts around 15–30° north and south of the equator, where dry air sinks from high up. Other causes of dryness are cold ocean currents, rain shadows behind mountains and great distance from the sea. With no clouds, days are very hot (often over 40 °C) and nights can be cold, so the daily range is large. The aridity index (P ÷ PET) tells how dry a place is: below 0.2 is arid. Soils are thin, sandy or stony and low in humus. Plants survive by storing water, having spines and wax, and deep or wide roots; animals by being active at night, burrowing and saving water. Deserts offer solar energy, minerals, farming with irrigation and tourism, but bring heat, water shortage, remoteness and flash floods. Desertification is good land turning into desert, caused by drought and climate change plus overgrazing, cutting trees, over-farming and population growth. It can be slowed by planting trees, careful grazing, water harvesting and new technology.
- Landforms and their Evolution: Work of Running Water and Wind – Running water and wind are two major agents that carve and build landforms. A river cuts deep V-shaped valleys, gorges, canyons, waterfalls and potholes in its steep upper course, and it builds alluvial fans, deltas, flood plains, natural levees and point bars where it slows down. Its bends (meanders) grow and are cut off to form oxbow lakes. In deserts, wind blows away loose sand (deflation), sand-blasts rock (abrasion) into mushroom rocks, and helps sheet floods wear land into pediments, pediplains and inselbergs; it deposits sand as dunes such as barchans, parabolic, seif, longitudinal and transverse dunes. Landforms go through stages, youth, maturity and old age, like living things.
3. 3.1.3 Coastal systems and landscapes (Section B option)
Coasts as natural systems · Systems and processes · Coastal landscape development · Coastal management · Quantitative and qualitative skills · Case studies
- Coastal Landscapes: How the Sea Shapes the Land – A coast is where land meets sea. It works as a system: energy from waves, tides, currents and wind moves sediment between stores such as cliffs, beaches and the sea bed, and each stretch of coast is a sediment cell. Waves form when wind blows over the sea; the fetch controls their size. Constructive waves build beaches; destructive waves remove them. High-energy coasts have big waves and cliffs; low-energy coasts have small waves, beaches and marshes. Weathering (freeze-thaw, salt, chemical) and mass movement (rockfall, landslide, slumping) weaken cliffs. The sea erodes by hydraulic action, abrasion, attrition and solution, transports by traction, saltation, suspension, solution and longshore drift, and deposits where energy drops. Erosion makes headlands and bays, wave-cut notches and platforms, and caves, arches, stacks and stumps. Deposition makes beaches, spits, bars, tombolos, sand dunes, mudflats and saltmarsh, especially in estuaries. Sea level changes (eustatic, isostatic, tectonic) create emergent coasts (raised beaches) and submergent coasts (rias, fjords). Climate change raises sea level and storminess. Coasts are managed by hard engineering, soft engineering, managed retreat, shoreline management plans and integrated coastal zone management.
- Movements of Ocean Water: Waves, Tides and Currents – Ocean water moves in three ways. Waves are made mostly by wind: the energy moves forward while each bit of water goes round in a small circle; waves slow down and break in shallow water. Tides are the regular rise and fall of the sea, usually twice a day, caused by the Moon's (and Sun's) pull and the Earth–Moon spin. When Sun, Moon and Earth line up (new and full moon) we get very high spring tides; when they are at right angles (quarter moons) we get weak neap tides. Ocean currents are huge rivers of water flowing in fixed directions, pushed by winds, heating, gravity, salinity and density differences, and turned by the Coriolis force. Warm currents flow from the equator towards the poles; cold currents flow from the poles towards the equator. Currents change coastal climates, fishing, fog and shipping.
4. 3.1.4 Glacial systems and landscapes (Section B option)
Glaciers as natural systems · The nature and distribution of cold environments · Systems and processes · Glaciated landscape development · Human impacts on cold environments · Quantitative and qualitative skills · Case studies
- Glacial Landscapes: How Ice Shapes Mountains and Valleys – A glacier is a slow river of ice. It works as a system: snow is added at the top (accumulation) and ice is lost at the bottom (ablation). The balance decides whether the snout advances or retreats. Ice erodes rock by freeze-thaw, plucking and abrasion. This makes corries, arêtes, pyramidal peaks, U-shaped troughs, hanging valleys and ribbon lakes. When ice melts it drops till, building moraines, drumlins and erratics; meltwater builds outwash plains, eskers and kames. Next to the ice, frozen ground makes periglacial features such as pingos and patterned ground. People farm, live and holiday in these uplands, and must manage tourism and climate change.
5. 3.1.5 Hazards (Section C option: choose one of hazards, ecosystems under stress)
The concept of hazard in a geographical context · Plate tectonics · Volcanic hazards · Seismic hazards · Storm hazards · Fires in nature · Case studies
- Natural Hazards – A natural hazard is a natural event that can harm people and property, such as an earthquake, volcano, landslide, flood, drought or cyclone. It becomes a disaster when it hits people who are not ready. Geological hazards come from inside the Earth; meteorological (weather) hazards come from the air and water. Risk = hazard × vulnerability ÷ capacity to cope, so warning systems, strong buildings and trained people cut the damage.
- Distribution of Oceans and Continents: Drift, Spreading and Plates – In 1912 Alfred Wegener said all continents were once one landmass, Pangaea, surrounded by one ocean, Panthalassa, and that they drifted apart. Matching coastlines, rocks, fossils, glacier deposits and placer gold supported him, but he could not explain the force. Mapping the ocean floor showed ridges, plains and trenches; Harry Hess then proposed sea-floor spreading: new crust forms at mid-ocean ridges and old crust sinks at trenches. This led to plate tectonics: the lithosphere is broken into rigid plates that move on the soft asthenosphere and meet at divergent, convergent and transform boundaries. The Indian plate broke away from the south, moved north, and collided with Asia to raise the Himalayas.
6. 3.1.6 Ecosystems under stress (Section C option)
Ecosystems and sustainability · Ecosystems and processes · Biomes · Ecosystems in the British Isles over time · Marine ecosystems · Local ecosystems · Case studies
- Biodiversity and its Conservation – Biodiversity is the variety of life at three levels: genetic, species and ecological. It is highest near the equator and grows with area (log S = log C + Z log A). Every species matters, like rivets on a plane. We are losing species fast because of the 'evil quartet': habitat loss and fragmentation, over-exploitation, alien species invasions and co-extinction. The IUCN Red List (Red Data Book) ranks species from Least Concern to Extinct. We protect life in situ (hotspots, national parks, sanctuaries, biosphere reserves, sacred groves, Ramsar wetlands) and ex situ (zoos, botanical gardens, seed and gene banks).
- Ecosystem: Structure, Productivity, Energy Flow and Pyramids – An ecosystem is a working unit of nature where living things (biotic) and non-living things (abiotic) interact. Plants make food at a rate called productivity: gross (GPP) minus respiration gives net (NPP = GPP − R). Dead matter is broken down in five steps: fragmentation, leaching, catabolism, humification and mineralisation. Energy enters as sunlight, flows one way through trophic levels and only about 10% passes on each time. Ecological pyramids of number, biomass and energy show this; number and biomass pyramids can be inverted, but the energy pyramid is always upright.
- Ecosystems in Depth: Biomes, Nutrient Cycles and Disruption – Biomes are large regions with similar climate and life. On land, temperature and rainfall decide the biome; in water, salt, depth, light and flow decide the zones. Matter cycles through ecosystems: nitrogen moves between air, soil, organisms and back through fixation, nitrification, assimilation, ammonification and denitrification; phosphorus cycles slowly between rock, soil, water, organisms and sediment with no gas stage. Decomposers recycle matter with oxygen (aerobic) or without it (anaerobic). Human actions such as fertiliser runoff, habitat loss, invasive species and climate change disrupt these systems; ecosystems respond with resistance and resilience.