AP Intermediate Geography (BIEAP) flashcards

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

Moho discontinuity

The boundary between Earth's crust and mantle where seismic wave velocities jump sharply; it lies about 35 km deep under continents and 5-10 km under oceans.

S-wave shadow zone

The region between 103 and 142 degrees from an earthquake epicentre where no S-waves are recorded, proving the outer core is liquid since shear waves cannot pass through fluids.

Isostasy

The state of gravitational balance where lighter crustal blocks float on the denser mantle; Airy varies root thickness, Pratt varies density at a constant depth.

Sea-floor spreading

Hess's model in which new oceanic crust forms at mid-ocean ridges and moves symmetrically outward, recorded by magnetic striping and age patterns on the ocean floor.

Epicentre versus focus

The focus is the underground point where an earthquake originates; the epicentre is the point on the surface directly above it, where shaking is usually strongest.

Karst topography

Landscape formed on soluble limestone by chemical solution, producing sinkholes, dolines, caves, stalactites, stalagmites, and disappearing underground streams.

Barchan dune

A crescent-shaped sand dune with horns pointing downwind, formed where sand supply is limited and wind direction is constant.

Soil horizons

Layers in a soil profile: O organic litter, A topsoil with humus, E leached zone, B accumulation zone, C weathered parent material, R bedrock.

Laterite soil

Tropical soil formed by intense leaching under alternating wet and dry seasons, rich in iron and aluminium oxides, poor in silica and nitrogen, hardening on exposure.

Alluvial fan

A fan-shaped deposit of sediment laid down where a steep mountain stream emerges onto a flatter plain and loses velocity.

Coriolis effect

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

ITCZ

The Intertropical Convergence Zone, a belt of low pressure near the equator where trade winds converge, producing heavy convectional rainfall and shifting seasonally.

Thermohaline circulation

Global deep-ocean circulation driven by differences in temperature and salinity; cold salty water sinks at high latitudes and drives slow overturning currents.

El Niño

Anomalous warming of the eastern equatorial Pacific caused by weakened trade winds, disrupting rainfall patterns worldwide with droughts and floods.

Monsoon reversal

A seasonal reversal of wind direction caused by differential heating of land and sea; the southwest monsoon brings summer rain to India.

Ocean salinity

The dissolved salt content of seawater, averaging about 35 parts per thousand, highest in subtropical high-evaporation belts and lowest near the equator and poles.

Demographic transition

A four-stage model of population change: high stationary, early expanding, late expanding, and low stationary, tracking falling death rates followed by falling birth rates.

Rule of seventy

A shortcut for doubling time: divide 70 by the annual percentage growth rate to estimate the years needed for a population to double.

Dependency ratio

The ratio of dependants under 15 and over 64 to the working-age population aged 15 to 64, multiplied by 100.

Primate city

A city at least twice the size of the next largest urban centre in a country, dominating national economic, political, and cultural functions.

Central place theory

Christaller's model of hexagonal market areas where settlements of different sizes provide services according to threshold population and range of goods.

Von Thünen model

A model of agricultural land use in concentric rings around a market, where perishability and transport cost determine which crops are grown nearest.

Weber's material index

The weight of localised raw materials divided by the weight of the finished product; above one favours material-oriented location, below one market orientation.

Break-of-bulk point

A location where cargo is transferred from one transport mode to another, often generating port or transshipment industries.

Comparative advantage

The principle that a country gains by specialising in goods it produces at lower opportunity cost, even if it is less efficient in absolute terms.

Footloose industry

An industry whose location is not tied to raw materials or power and can be sited flexibly, often light manufacturing or service activities.

Northeast monsoon

The October to December monsoon that brings rain to India's Coromandel coast and coastal Andhra Pradesh after the southwest monsoon withdraws.

Deccan Trap

A large igneous province in peninsular India formed by basaltic lava flows, weathering into fertile black cotton soil.

Godavari delta

The fertile delta in Andhra Pradesh where the Godavari River splits before entering the Bay of Bengal, known as a major rice-producing region.

Kolleru Lake

A shallow freshwater lake between the Godavari and Krishna deltas in Andhra Pradesh, an important wetland and bird habitat.

Representative fraction

A map scale expressed as a ratio such as 1:50,000, meaning one unit on the map equals 50,000 of the same units on the ground.

Contour spacing

The distance between contour lines on a map; closely spaced lines indicate steep slopes, widely spaced lines indicate gentle slopes.