🌍 Year 10 Geography

Tectonic Hazards

Plate Tectonics

• The Earth's lithosphere is divided into tectonic plates that move on the asthenosphere (semi-molten mantle) due to convection currents heated by radioactive decay in the core
• Destructive (convergent) plate boundary: plates move towards each other. Oceanic plate subducts beneath continental plate → deep ocean trenches, fold mountains (Andes), explosive volcanoes, earthquakes. Example: Nazca Plate / South American Plate.
• Constructive (divergent) plate boundary: plates move apart. Magma rises to fill the gap → new crust formed, shield volcanoes, rift valleys, mid-ocean ridges. Example: North American / Eurasian plates (Iceland).
• Conservative (transform) plate boundary: plates slide past each other. No magma, so no volcanoes — but frequent powerful earthquakes. Example: San Andreas Fault, California (Pacific Plate / North American Plate).
• Collision boundary: two continental plates collide (neither subducts) → fold mountains (Himalayas). Earthquakes, no volcanoes.

Earthquakes

• Caused by the sudden release of energy as rocks fracture along faults. The focus is where the earthquake starts underground. The epicentre is the point on the surface directly above the focus.
• Seismic waves spread outward from the focus. P-waves (primary, compressional) and S-waves (shear) travel through rock; surface waves cause most damage.
• Magnitude measured on the Richter/Moment Magnitude Scale. Logarithmic: magnitude 7 is 10× more powerful than magnitude 6.
• Case study — L'Aquila, Italy (2009, LIC context) vs Haiti (2010): compare death tolls, economic damage, and effectiveness of response. Consider why LICs suffer more deaths from similar-magnitude earthquakes (building quality, emergency services, governance).
• Reducing risk: earthquake-proof buildings (cross-bracing, rubber-padded foundations), early warning systems, tsunami barriers, community education.

Volcanoes

• Shield volcanoes (constructive boundaries): wide, gently sloping; runny basaltic lava; relatively gentle eruptions. Hawaii.
• Composite/strato volcanoes (destructive boundaries): steep-sided; viscous lava traps gas; explosive eruptions of ash, pyroclastic flows, lahars. Mt Pinatubo, Mt St Helens.
• Supervolcanoes (hotspots): enormous magma chambers. Eruptions rare but globally catastrophic. Yellowstone (USA) — next eruption would affect climate worldwide.
• Benefits of living near volcanoes: fertile volcanic soil (agriculture), geothermal energy, tourism, mineral deposits

Weather Hazards

Global Atmospheric Circulation

• Three circulation cells per hemisphere: Hadley Cell (0°–30°), Ferrel Cell (30°–60°), Polar Cell (60°–90°)
• Hadley Cell: rising air at the equator (low pressure, high rainfall = tropical rainforests) → air moves poleward → sinks at 30° (high pressure, little rainfall = hot deserts like Sahara)
• Drives prevailing winds: trade winds, westerlies, polar easterlies

Tropical Storms

• Also called hurricanes (Atlantic), cyclones (Indian Ocean), typhoons (Pacific)
• Formation: warm ocean water (>26°C) evaporates → warm, moist air rises rapidly → cools, condenses (releasing latent heat) → creates the storm engine. Form between 5°–20° latitude where the Coriolis effect spins the storm.
• Structure: eye (calm, lowest pressure), eye wall (strongest winds, heaviest rain), spiral rain bands
• Impacts: storm surge flooding, high winds destroy buildings, landslides, disease, economic damage
• Case study: Typhoon Haiyan (2013, Philippines — LIC): 6,000+ deaths, 4 million homeless, storm surge up to 7m. Aid was slow to reach remote islands. Long-term reconstruction challenges.
• Responses: early warning systems, evacuation, storm-resistant building codes, mangrove restoration (coastal protection)

UK Extreme Weather

• The UK has a temperate maritime climate — usually mild and wet. But extreme events do occur.
• Summer 2022 heatwave: temperatures exceeded 40°C in England for the first time. Strain on NHS, transport delays (rail lines buckled), wildfires.
• Flooding: 2013–2014 Somerset Levels — prolonged rainfall, saturated soil, coastal storm surges. Dredging debate vs natural flood management.
• Evidence that extreme weather events are becoming more frequent and intense due to climate change

Climate Change

Evidence for Climate Change

• Glacial retreat: glaciers worldwide are receding. The Mer de Glace (France) has retreated significantly since records began.
• Sea level rise: thermal expansion of oceans + melting ice sheets. Global sea levels have risen about 20 cm since 1900; the rate is accelerating.
• Temperature records: 2023 and 2024 were the warmest years on record globally. 19 of the 20 hottest years ever have occurred since 2002.
• Ice core data and tree rings: provide evidence of past climate conditions over hundreds of thousands of years

Causes

• Enhanced greenhouse effect: CO₂, methane, nitrous oxide, water vapour trap outgoing infrared radiation. Natural greenhouse effect is essential for life; the enhanced version is causing warming.
• Human causes: burning fossil fuels (power stations, transport), deforestation (trees absorb CO₂), agriculture (methane from livestock and rice paddies), cement manufacture
• Natural causes: Milankovitch cycles (changes in Earth's orbit and tilt), solar output variation, volcanic eruptions — but these CANNOT explain the current rate of warming

Managing Climate Change

• Mitigation (reducing causes): transition to renewable energy (wind, solar, tidal), electric vehicles, carbon capture and storage, reforestation, international agreements (Paris Agreement 2015 — limit warming to 1.5°C above pre-industrial levels)
• Adaptation (adjusting to impacts): flood defences, drought-resistant crops, managed retreat from coastlines, heat-resilient urban planning
• Challenges: international co-operation needed but countries have different priorities; LICs contribute least to climate change but suffer most; cost of transition

Ecosystems

What is an Ecosystem?

• An ecosystem is a community of plants and animals interacting with each other and their physical environment (climate, soils, water)
• Nutrient cycle: nutrients are stored in biomass (living material), litter (dead material on the ground), and soil. The flows between them depend on climate (rainfall, temperature).
• Global ecosystems (biomes): determined primarily by temperature and rainfall. From equator to poles: tropical rainforest → savanna → hot desert → Mediterranean → temperate grassland/deciduous forest → boreal (taiga) forest → tundra → ice cap.
• Interdependence: change one element and the whole system is affected. Remove a predator → prey population explodes → vegetation is overgrazed.

Tropical Rainforests

Characteristics and Adaptations

• Located near the equator (0°–10° north and south). Temperature ~27°C year-round. Rainfall >2,000 mm/year. High biodiversity.
• Vegetation layers: emergent layer (>40m), canopy (20–30m, closes overhead — blocks 80% of sunlight), understorey, forest floor (dark, few plants but many decomposers)
• Nutrient cycle: rapid decomposition (heat, moisture) means nutrients cycle quickly through the ecosystem. If the trees are removed, the thin, infertile soil is quickly exhausted and eroded.
• Adaptations: buttress roots (support tall trees in thin soil), drip-tip leaves (shed heavy rain), lianas, epiphytes, bright flowers attracting specific pollinators, fig trees fruiting year-round to sustain animal populations

Deforestation

• Causes: commercial farming (cattle ranching, soya plantations for animal feed), commercial logging (mahogany, rosewood), road building, mineral extraction (iron ore, bauxite), hydroelectric power, subsistence farming
• Impacts: loss of biodiversity (many species not yet discovered), disruption of the water cycle (trees transpire vast quantities — deforestation → drier climate), soil erosion, loss of carbon store → accelerating climate change, loss of medicines from forest plants, destruction of indigenous communities
• Case study — Amazon, Brazil: deforestation peaked in 2004 (27,000 km²/year). Government of Lula reduced rates significantly. Under Bolsonaro (2019–2022), rates rose again. International pressure, REDD+ schemes (Reducing Emissions from Deforestation and Forest Degradation).
• Sustainable management: selective logging, replanting, eco-tourism, debt-for-nature swaps, certifying sustainable timber, protected areas

Hot Deserts

Characteristics and Adaptations

• Located around 30°N and 30°S (high pressure zones where dry descending air produces little rainfall). Rainfall <250 mm/year. Extreme temperatures (up to 50°C by day, below 0°C at night). Low biodiversity.
• Soil: thin, sandy/stony, lacking organic matter. Little water to weather rock. Wind erosion shapes the landscape (dunes, yardangs).
• Plant adaptations: cacti (store water in succulent stems, shallow wide-spreading roots to capture rain, spines to deter herbivores), deep-rooted plants (acacia), dormancy during drought, waxy/leathery leaves to reduce water loss
• Animal adaptations: nocturnal behaviour (avoid daytime heat), concentrated urine (conserve water), pale colouring (reflect heat), burrowing

Development and Desertification

• Opportunities in hot deserts: mineral extraction (oil, gold, copper), solar energy (intense sunlight), tourism (sahara, dunes, wildlife)
• Challenges: extreme heat, water shortage, remoteness, fragile ecosystems easily damaged
• Case study — Thar Desert, Rajasthan, India: 200 million people live in or near it. Subsistence agriculture, camel herding. The Indira Gandhi Canal has enabled irrigation but brought waterlogging and salinisation.
• Desertification: the process by which semi-arid land becomes increasingly arid and unproductive. Causes: overgrazing, deforestation, soil erosion, climate change, population pressure. The Sahel region (south of the Sahara) is particularly vulnerable.
• Strategies to reduce desertification: stone lines to slow runoff, magic stones technique, half-moon planting pits, tree planting (Great Green Wall initiative), sustainable farming practices

River Landscapes in the UK

The Long Profile and River Processes

• The long profile of a river changes from its source (upper course) to its mouth (lower course): steep → gentle gradient
• Erosion processes: hydraulic action (force of water), abrasion (sediment acts as sandpaper), attrition (particles collide and break), solution (chemical dissolution of limestone)
• Transportation: traction (large boulders rolled), saltation (bouncing), suspension (smaller particles carried), solution (dissolved)
• Deposition: when a river loses energy (velocity decreases) it deposits sediment — heaviest particles first, finest last
• Hjulström Curve: shows the relationship between velocity and particle size for erosion, transportation, and deposition

River Landforms

• Upper course: V-shaped valleys, waterfalls and gorges (resistant rock over less resistant rock; hydraulic action and abrasion undercut the rock → overhang collapses), interlocking spurs
• Middle course: meanders (lateral erosion — river swings sideways; erosion on the outside of the bend = river cliff; deposition on the inside = slip-off slope)
• Lower course: oxbow lakes (meander cutoff — neck narrows, river cuts through at flood, former meander becomes isolated), floodplains (flat land either side of river built up by deposited alluvium over many floods), levées (raised banks of coarser sediment deposited first when river floods)
• Estuary: where river meets sea. Tidal influence. Saltmarsh. Mudflats from fine deposition.

River Flooding and Management

• Causes of flooding: prolonged rainfall (saturated soil), intense rainfall, snowmelt, hard impermeable surfaces in urban areas (rapid runoff), deforestation (less interception and transpiration)
• Case study — Boscastle, Cornwall 2004: flash flood caused by intense rainfall on hard moorland. Narrow valley concentrated the flood. Village devastated. 75 cars and 6 buildings destroyed. No deaths (despite scale) — fortunate.
• Hard engineering: embankments/levées, flood walls, dams and reservoirs, channel straightening (dredging). Effective but expensive and can shift flood risk downstream.
• Soft engineering/flood management: flood plain zoning (no building on flood plains), washlands (allowing designated areas to flood), afforestation upstream (trees intercept rainfall and slow runoff), sustainable urban drainage (permeable paving, retention ponds). More sustainable and cheaper long-term.

Fieldwork & Geographical Skills

GCSE Fieldwork Requirements

• All GCSE Geography students must carry out two pieces of fieldwork: one human geography enquiry, one physical geography enquiry
• The enquiry process: identifying a question → designing a methodology → collecting data → presenting data → analysing and concluding → evaluating

Key Skills

• Map reading: OS maps — six-figure grid references, scale and distance, contour lines (height and steepness), map symbols
• Graphs: choosing the right type — pie charts (proportions), bar charts (comparing categories), line graphs (change over time), scatter graphs (correlations), climate graphs (temperature and rainfall)
• Statistical measures: mean, median, mode, range, interquartile range. The Spearman's Rank correlation coefficient: tests the strength of the relationship between two variables. r = +1 (perfect positive), −1 (perfect negative), 0 (no correlation).
• Sampling: random, systematic, stratified — choosing the method to suit the enquiry and justifying the choice
• GIS (geographical information systems): layering different data sets to analyse patterns