JC Geography key terms

The line where two tectonic plates meet. At constructive boundaries plates move apart, at destructive boundaries one plate sinks beneath another, and at conservative boundaries they slide past each other.

The process where a denser oceanic plate is forced down beneath a lighter continental plate at a destructive boundary, creating deep ocean trenches, earthquakes and chains of volcanoes.

A mountain range formed when layers of sedimentary rock are compressed and buckled upwards by the collision of two plates, for example the Himalayas.

The breakdown of rock in place by physical, chemical or biological processes. Unlike erosion, the broken material is not carried away by a moving agent.

The wearing away of rock and soil by moving agents such as rivers, waves, ice or wind, followed by the transport of the loosened material to a new location.

The downhill transfer of soil and rock under the influence of gravity, ranging from slow soil creep to fast landslides and rockfalls, often triggered when slopes become saturated.

The zigzag movement of sediment along a coastline caused by waves approaching at an angle, carrying material up the beach and letting it slide back with the backwash.

A narrow ridge of sand or shingle that extends from the land into the sea, built up by longshore drift and often ending in a curved hook where the current weakens.

The whole area of land drained by a river and its tributaries, bounded by a watershed. It collects precipitation and delivers it through a channel to the sea.

A graph plotting river discharge against time after a rainfall event, showing the lag time between peak rainfall and peak flow and revealing how quickly a basin responds.

The apparent deflection of moving air or water caused by the Earth's rotation, turning winds to the right in the northern hemisphere and to the left in the southern hemisphere.

The difference in atmospheric pressure between two places over a given distance. A steep gradient produces strong winds blowing from high to low pressure.

Steady easterly winds blowing from the subtropical high-pressure belts towards the equatorial low, deflected by the Coriolis effect and important for sailing and for driving ocean currents.

A belt of low pressure near the equator where the trade winds from each hemisphere meet and rise, producing heavy convectional rainfall and shifting seasonally with the overhead sun.

Rain caused when moist air is forced to rise over hills or mountains, cooling and condensing on the windward side and leaving a drier rain shadow on the leeward side.

Rain produced when a warm air mass meets a colder one, rises over it along the front, cools and condenses to form cloud and prolonged or heavy precipitation.

A line on a weather map joining places of equal atmospheric pressure. Closely spaced isobars indicate strong winds; widely spaced ones indicate light winds.

The tendency of a built-up area to be warmer than its surrounding countryside, caused by heat-absorbing surfaces, trapped heat between buildings and human energy use.

The small-scale climate of a particular site, such as a street, garden or valley, which can differ noticeably from the wider regional climate because of aspect, shelter or surface cover.

The number of live births per thousand people in a population in a given year, used with death rate to calculate natural population change.

The number of deaths per thousand people in a population in a given year. Compared with the birth rate it shows whether a population is growing or shrinking naturally.

A graph showing the age and sex structure of a population using horizontal bars. Its shape reveals past trends such as baby booms, war losses or high infant mortality.

The proportion of a population that is too young or too old to work compared with the working-age group, expressed as dependants per hundred workers.

A negative condition at a place of origin, such as unemployment, conflict or drought, that encourages people to leave and migrate elsewhere.

A positive attraction at a destination, such as better-paid work, education or healthcare, that draws migrants towards it.

The movement of people from the countryside to towns and cities, usually in search of work and services, and a major cause of rapid urban growth in lower-income countries.

The increasing proportion of a country's population living in towns and cities, driven by rural-urban migration and by natural increase within urban areas.

A ranking of settlements by size and the number and range of services they provide, from isolated farms and villages up to towns and cities.

The area from which a settlement or service draws its customers, larger for higher-order services such as hospitals than for low-order ones such as a corner shop.

The part of an economy concerned with extracting raw materials directly from the environment, including farming, fishing, forestry and mining.

The part of an economy that processes raw materials into manufactured goods, covering sectors such as textiles, food processing, steel and car assembly.

The part of an economy that provides services rather than goods, including retail, transport, tourism, banking, education and healthcare.

The total value of goods and services produced within a country in a year, often expressed per head of population as a broad measure of economic output.

A composite measure of development combining life expectancy, education and income per person, giving a broader picture than income alone.

A large company that operates in several countries, often locating production where costs are low and selling in markets worldwide, and able to influence local economies strongly.

The growing interconnection of economies and societies worldwide through trade, investment, migration and communication, spreading ideas, goods and jobs across national borders.

Selecting a representative subset of sites or people to measure in fieldwork, using methods such as random, systematic or stratified sampling to reduce bias.

A small trial run of a fieldwork method carried out before the main data collection to test equipment, refine techniques and identify practical problems.

A testable statement predicting a relationship between variables, which fieldwork data are collected to support or reject.

A line on a map joining points of equal height above sea level. The closer the lines, the steeper the slope.

The ratio between distance on a map and the real distance on the ground, for example 1:50 000, used to measure real distances and judge the size of features.

A set of numbers locating a point on a map using the grid lines, given as eastings before northings, with four figures giving a square and six a more precise point.

A profile drawn along a line on a map showing the shape of the land between two points, constructed by transferring heights from contour lines onto a graph.