KSEAB II PUC Geography key terms

The overall wearing away of the land surface by weathering, mass movement, erosion and transport, lowering relief over time. It includes both the breakdown of rock in place and the removal of the debris.

The in-place breakdown or decay of rocks and minerals at or near the surface, caused by physical, chemical or biological processes. The broken material stays where it formed unless moved by gravity, water or wind.

The removal and transport of weathered rock debris by a moving agent such as running water, wind, waves or ice. It differs from weathering because material is carried away from its original position.

Downslope movement of soil and rock under gravity without a transporting medium such as water or wind. It ranges from slow creep to rapid landslides and is favoured by steep slopes, weak material and saturation.

The laying down of eroded sediment when the transporting agent loses energy, for example where a river slows on entering a plain or the sea. Deposits build landforms such as deltas, floodplains and sand dunes.

The lowest level to which a river can erode its bed, usually sea level for a river reaching the coast. As base level falls, the river cuts down again, producing rejuvenated valleys and terraces.

A step-like bench of former floodplain left above the present river level after renewed downcutting. Terraces mark earlier valley floors and are often used for settlement and farming because they are flat and well drained.

The flat land beside a river built up by sediment deposited during floods. It is generally fertile and favoured for agriculture but is also the zone most exposed to flooding.

A low, often triangular tract of sediment deposited where a river enters a standing body of water and loses velocity. Deltas form where sediment supply is high and tidal or wave removal is weak.

The incoming solar radiation received at the Earth's surface. Its intensity varies with latitude, season and angle of the sun, and it is the main energy source driving atmospheric circulation.

The proportion of incoming solar radiation reflected back to space by a surface, expressed as a fraction or percentage. Snow and cloud reflect much; dark forest and ocean reflect little, affecting local heating.

The rate at which atmospheric pressure changes with horizontal distance. Air accelerates from high to low pressure, so a steep gradient produces strong winds; the gradient force is balanced by the Coriolis force in free air.

The apparent deflection of moving air or water caused by the Earth's rotation. Deflection is to the right in the Northern Hemisphere and to the left in the Southern, and is zero at the equator.

A seasonal reversal of prevailing wind direction, bringing a marked wet season and dry season. The South Asian monsoon is driven by differential heating of land and sea plus the shift of the ITCZ.

A dry region on the leeward side of a mountain range, where descending air has already lost its moisture on the windward slope. In India this explains the dry interior of the Deccan behind the Western Ghats.

Rain produced when moist air is forced to rise over hills or mountains, cools and condenses. Heavy rain falls on the windward slope while the leeward side stays drier.

The slow, global overturning of ocean water driven by differences in temperature and salinity, and therefore density. It moves heat between tropics and poles and is distinct from wind-driven surface currents.

A large-scale, persistent movement of surface or deep ocean water in a preferred direction. Surface currents are driven mainly by prevailing winds and deflected by the Coriolis effect, moderating coastal climates.

The total mass of dissolved salts in seawater, usually expressed in parts per thousand. It is highest in warm, evaporative subtropical seas and lowered near large river mouths and in cold polar water.

The regular rise and fall of sea level caused mainly by the gravitational pull of the Moon and Sun. Spring tides occur at new and full moon, neap tides at quarter phases.

The average number of people per unit area, usually persons per square kilometre. It reveals crowding but hides internal variation, so it is often paired with distribution maps.

The pattern of where people live across a territory, described as clustered, dispersed, linear or nucleated. It reflects terrain, climate, water supply, soils and economic opportunity.

The number of females per 1,000 males in a population. In India it is a key social indicator, and a low child sex ratio signals discrimination against girls.

The percentage of the population aged seven and above who can read and write with understanding. It is a basic measure of human development and shows wide gaps by gender and region.

The rising share of a population living in towns and cities, together with the growth of urban areas. It results from rural-to-urban migration and from natural increase within towns.

A continuous built-up area formed when expanding towns merge into one another, though each keeps its own administration. It creates shared problems of transport, water supply and waste disposal.

Fertile soil formed from sediment deposited by rivers, common across the northern plains and deltas of India. It is generally rich in potash and lime but may be poor in nitrogen and organic matter.

Dark clay-rich soil, also called regur, formed from weathered basalt and found mainly on the Deccan lava plateau. It holds moisture well and is prized for cotton, but becomes sticky when wet and cracks when dry.

A leached, iron-rich soil of hot, wet tropical areas, formed when heavy rain removes silica and leaves iron and aluminium oxides behind. It is often acidic and infertile unless heavily manured.

The two main Indian cropping seasons. Kharif crops are sown with the monsoon and harvested in autumn, while rabi crops are sown after the rains and harvested in winter or spring.

The number of crops grown on the same land in one agricultural year, often expressed as a percentage of the net sown area. Assured irrigation and short-duration varieties raise it.

The artificial supply of water to farmland to supplement rainfall. In India it comes from canals, tanks and wells, and it stabilises yields and allows a second crop.

Ploughing along lines of equal elevation rather than up and down a slope. The furrows slow runoff and check soil erosion on hilly farmland.

The removal of the topsoil by water or wind faster than it can form. It thins the fertile layer, reduces yields and silts reservoirs, and is worsened by deforestation and overgrazing.

A large-scale map showing relief by contours, along with settlement, drainage, roads, land use and other features. In Indian practical work it is usually a Survey of India sheet at 1:50,000 scale.

A line joining points of equal height above mean sea level. Closely spaced contours indicate a steep slope, widely spaced ones a gentle slope, and concentric closed loops a hill or a depression.

A set of easting and northing values that locates a point on a map by its grid square. It is written with eastings before northings, giving a precise and repeatable location.

A statistical diagram in which quantities are shown by bars of proportional length or height. Simple, multiple and subdivided forms compare totals, groups and components respectively.

A circular diagram divided into sectors whose angles are proportional to the parts of a total. It shows the composition of a single quantity, such as the share of land under different crops.

A map in which administrative units are shaded or patterned according to the value of a variable. It suits density and percentage data and needs a clear graded key.