LGCSE Geography flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Hydraulic action

River or wave erosion process where the force of moving water traps and compresses air in cracks, weakening and eventually breaking rock apart along joints and bedding planes.

Barchan dune

Crescent-shaped sand dune with horns pointing downwind, formed where sand supply is limited and wind direction is consistent across a flat desert surface.

Corrie (cirque)

Armchair-shaped hollow on a mountainside eroded by a glacier; after ice retreat it may fill with water to form a tarn behind a rock lip.

Albedo

Proportion of incoming solar radiation reflected by a surface; ice and snow have high albedo, dark ocean and forest low albedo, affecting local and global energy balance.

Relief rainfall

Orographic rainfall produced when moist air is forced to rise over hills or mountains, cooling and condensing on the windward slope, leaving a drier leeward rain shadow.

Enhanced greenhouse effect

Extra warming caused by human emissions of greenhouse gases, which absorb outgoing longwave radiation and raise average global temperatures beyond natural background levels.

Urban heat island

Phenomenon where built-up areas are warmer than surrounding countryside, caused by low-albedo surfaces, reduced vegetation, heat storage and traffic emissions.

Trophic level

Position of an organism in a food chain, such as producer, primary consumer or decomposer; energy decreases at each higher level through respiration and waste.

Ecological succession

Gradual change in species composition of a community over time, from pioneer species on bare ground through seral stages towards a stable climax community.

Biome

Large-scale ecosystem defined by climate, vegetation and animal life, such as tropical rainforest, savanna, desert, temperate deciduous forest, taiga and tundra.

Dependency ratio

Number of people below working age plus those above it, divided by the working-age population, expressed as a ratio or percentage indicating economic burden.

Demographic Transition Model

Five-stage model describing how birth and death rates change as a country develops, from high-high in Stage 1 to low-low in Stage 4 and possible decline in Stage 5.

Push factor

Negative condition at a place of origin, such as poverty, unemployment, conflict or drought, that encourages people to migrate away from that area.

Central place theory

Model explaining settlement size and spacing: settlements provide goods to surrounding areas, with higher-order centres offering a wider range of services and larger thresholds.

HDI

Human Development Index, a composite measure from 0 to 1 combining life expectancy, education and income per capita to compare development between countries.

Transnational corporation

Large company operating production or services in several countries, locating activities to access markets, cheaper labour or resources and spreading risk across regions.

Fair trade

Trading arrangement guaranteeing producers a minimum price plus a social premium, aiming to improve incomes and working conditions in developing countries.

Bid-rent theory

Model stating land value is highest in the city centre and declines outward, so competition allocates central land to high-profit activities such as retail.

Counter-urbanisation

Movement of people from large cities to smaller towns and rural areas, driven by high housing costs, congestion, remote work and quality-of-life preferences.

Squatter settlement

Unplanned housing built without legal tenure, typically on marginal land in rapidly growing cities, often lacking secure water, sanitation and electricity.

Hydrograph lag time

Delay between peak rainfall and peak river discharge; shortened by urbanisation, steep slopes, impermeable rock and saturated soils, lengthened by vegetation and permeable ground.

Hard engineering

Flood or coastal defence using built structures such as dams, levees, sea walls and groynes, which give strong protection but are costly and may cause downstream or downdrift effects.

Soft engineering

Flood or coastal management working with natural processes, including beach nourishment, dune stabilisation, afforestation, wetland restoration and floodplain zoning.

Sediment cell

Coastal system with inputs, transfers and outputs of sediment between defined boundaries; groynes and dams can interrupt movement and starve downdrift beaches.

Systematic sampling

Fieldwork technique selecting points at regular intervals along a line or grid, giving even coverage but risking bias if the interval matches a repeating feature.

Interquartile range

Difference between the upper and lower quartiles of a data set, describing the spread of the middle half and reducing the influence of extreme outliers.

Primary data

Information collected first-hand by the researcher for a specific investigation, such as measurements, questionnaires or field counts, controlled for accuracy and relevance.

Six-figure grid reference

Location method giving eastings then northings to three digits each, pinpointing a position within a 100-metre square on a 1:50,000 map.

Contour interval

Vertical height difference between consecutive contour lines on a map; closely spaced contours show steep slopes, widely spaced contours show gentle slopes.

Choropleth map

Map shading administrative areas in graded tones to represent density or rate values, effective for showing patterns but masking variation within each area.

GIS overlay

Analysis combining two or more spatial data layers, such as flood zones and housing, to identify relationships and support planning decisions.

Extrapolation

Estimating values beyond the range of observed data by extending a trend; less reliable than interpolation because the underlying relationship may change.