JC Geography cheat sheet

Plate boundaries: divergent (constructive) plates move apart, magma rises and new crust forms; convergent (destructive) plates collide, giving subduction trenches or fold mountains; transform (conservative) plates slide past each other, producing faults and earthquakes but no volcanism.

Subduction occurs where an oceanic plate meets a continental or older oceanic plate; the denser plate sinks, generating deep-sea trenches, island arcs and explosive andesitic volcanism.

Hotspot volcanism (e.g. Hawaii) forms chains of islands as a plate moves over a fixed mantle plume; age of islands increases away from the plume.

Weathering types: mechanical (freeze-thaw, exfoliation, salt crystal growth), chemical (carbonation, oxidation, hydrolysis) and biological (root action, burrowing).

Mass movement classification by speed and water content: soil creep (slow, imperceptible), solifluction (slow flow in periglacial areas), mudflow (fast, saturated), landslide and rockfall (fast, dry).

River processes: erosion by hydraulic action, abrasion, attrition and solution; transportation by traction, saltation, suspension and solution; deposition occurs when velocity and discharge fall.

Long profile of a river is concave: steep gradient in the upper course, gentle in the lower course; cross-profile changes from narrow and deep V-shaped valleys to wide flat floodplains.

Coastal landforms: discordant coasts (alternating rock types) give headlands and bays; concordant coasts give straight cliffs; longshore drift moves sediment in the direction of the dominant wave approach.

Karst features (limestone): carbonation weathering dissolves calcium carbonate, forming swallow holes, stalactites, stalagmites, caverns and dry valleys; impermeable rock beneath limestone creates springs.

Atmospheric composition by volume: nitrogen about 78%, oxygen about 21%, argon about 0.9%, carbon dioxide about 0.04%; water vapour varies from near 0% to 4%.

Lapse rates: the environmental lapse rate averages about 6.5 °C per 1000 m in the troposphere; the dry adiabatic lapse rate is 9.8 °C per 1000 m, and the saturated adiabatic lapse rate is about 6 °C per 1000 m.

Air becomes unstable when the environmental lapse rate exceeds the saturated adiabatic lapse rate; this favours convection, towering cumulus and thunderstorms.

Pressure systems: low pressure (cyclone) brings rising air, cloud and rain; high pressure (anticyclone) brings subsiding air, clear skies, light winds and temperature inversions in winter.

Frontal rainfall occurs where warm air rises over cold air at a warm or cold front; relief rainfall occurs as moist air is forced to rise over high ground; convectional rainfall follows intense surface heating.

Coriolis effect deflects moving air to the right in the Northern Hemisphere and to the left in the Southern Hemisphere; geostrophic wind flows parallel to isobars where pressure gradient and Coriolis forces balance.

Climate controls: latitude (insolation angle), altitude, distance from the sea (continentality), ocean currents, prevailing winds, aspect and relief.

El Niño–Southern Oscillation: El Niño brings weakened trade winds, warm surface water in the eastern Pacific and drought in Australia; La Niña reverses these patterns.

Urban heat island: city centres are warmer than surrounding rural areas because of low albedo surfaces, reduced evapotranspiration, anthropogenic heat and trapped long-wave radiation.

Demographic Transition Model stages: high stationary (high birth and death rates), early expanding, late expanding (birth rate falling), low stationary, and declining (birth rate below death rate).

Natural increase rate = (birth rate − death rate) per 1000; doubling time can be estimated by the rule of 70: 70 ÷ annual growth rate (%).

Population pyramid shapes: broad base and narrow apex indicate a youthful, rapidly growing population; a narrow base with a wide apex indicates an ageing, declining population.

Dependency ratio = (population aged under 15 + population aged 65 and over) ÷ working-age population (15–64) × 100.

Push factors (drought, conflict, unemployment, overcrowding) drive emigration; pull factors (jobs, education, healthcare, political stability) attract immigration; intervening obstacles reduce migration flows.

Settlement site factors: water supply, flat land, fertile soil, defensive relief, bridging points, shelter and aspect; situation factors relate to routes and surrounding resources.

Urban land-use models: Burgess concentric zone model (rings outward from the CBD), Hoyt sector model (wedges along transport routes) and Harris–Ullman multiple nuclei model (several centres).

Rural–urban migration is driven by mechanisation of agriculture and urban employment; consequences include shanty settlements, pressure on infrastructure and remittances sent to rural areas.

Settlement hierarchy: higher-order settlements have larger populations, more services and larger sphere of influence; the rank–size rule suggests the nth-ranked settlement has 1/n the population of the largest.

Sector classification: primary (extraction, farming, fishing), secondary (manufacturing, construction), tertiary (services, retail, tourism) and quaternary (research, ICT, finance).

Clark–Fisher model: as economies develop, employment shifts from primary to secondary and then to tertiary and quaternary sectors.

Gross National Income (GNI) per capita and Gross Domestic Product (GDP) per capita measure economic output; the Human Development Index combines life expectancy, education (mean and expected years of schooling) and GNI per capita.

Purchasing power parity (PPP) adjusts income figures for differences in local cost of living, allowing fairer international comparison.

The Brandt line divides the relatively wealthy Global North from the poorer Global South; the concept is criticised for oversimplifying inequality within countries.

Factors affecting industrial location: raw materials, power supply, labour cost and skill, transport, market access, government policy and agglomeration economies.

Multinational corporations (MNCs) locate branch plants to reduce costs (cheaper labour, laxer environmental rules) and access markets; host countries gain jobs but may face profit repatriation and environmental degradation.

Fair trade guarantees a minimum price to producers, a social premium and long-term contracts; it aims to reduce producer vulnerability to commodity price fluctuations.

Sustainable development balances economic growth, social equity and environmental protection; indicators include the ecological footprint and the Sustainable Development Goals.

Sampling methods: random (coordinates or random number tables), systematic (regular intervals along a transect) and stratified (sampling proportional to subgroup size); larger samples reduce sampling error.

River fieldwork measurements: velocity by float or current meter (velocity = distance ÷ time), discharge = cross-sectional area × mean velocity, and bedload size by pebble callipers with a Powers scale.

Beach profiles are measured with a ranging pole, tape and clinometer; the angle of slope = tan⁻¹(vertical difference ÷ horizontal distance).

Infiltration rate is measured by pouring a known volume of water into a soil pipe and recording the time taken for it to disappear; rate = volume ÷ time.

Soil texture is assessed by hand texturing or sedimentation; soil pH by indicator or pH meter; soil moisture by drying a sample and calculating percentage loss of mass.

Environmental quality surveys use an ordinal scale (e.g. 1–5) and are subjective; reliability improves with multiple surveyors and repeat observations.

Risk assessment for fieldwork must identify hazards (fast-flowing water, steep slopes, weather, traffic) and controls (buoyancy aids, buddy system, appropriate clothing, first-aid provision).

Data presentation choices: bar charts for discrete categories, histograms for continuous data, scatter graphs for correlation, choropleth maps for density and kite diagrams for transect data.

Map scale: 1:50,000 means 1 cm on the map represents 0.5 km on the ground; 1:25,000 means 1 cm represents 0.25 km.

Grid references: four-figure references give the grid square (eastings before northings); six-figure references give a point to 100 m precision, again eastings before northings.

Contour lines join points of equal height; closely spaced contours indicate steep slopes, widely spaced contours indicate gentle slopes, and hachures or cliff symbols mark vertical drops.

Bearings are measured clockwise from grid north, from 0° to 360°; magnetic north differs from grid north by magnetic declination, which changes over time.

Cross-sections are drawn by plotting heights along a transect between two grid references and joining the points; vertical exaggeration = vertical scale ÷ horizontal scale.

Relief and drainage interpretation: V-shaped contour patterns pointing upstream indicate valleys; contour patterns pointing downstream indicate spurs; a confluence occurs where two rivers meet.

Settlement site reading on maps: look for churches, post offices, schools, road junctions, bridging points and contour patterns to infer function and growth.

Distance and area measurement: use a ruler or string for curved routes, then convert using the scale; area can be estimated by counting grid squares or using the grid-square method.

Choropleth maps use shading to show density per unit area; they can mislead where administrative areas vary greatly in size, so the map must state the class intervals.