NSSCO Geography 6137 flashcards

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

Earth's outer core

The liquid layer of iron and nickel between the mantle and the inner core; its movement generates the Earth's magnetic field.

Divergent plate boundary

A boundary where two plates move apart and magma rises to form new crust, as at the Mid-Atlantic Ridge, producing earthquakes and volcanic activity.

Sedimentary rock

Rock formed when layers of sediment are compacted and cemented over time; examples include sandstone, limestone and shale, often containing fossils.

Freeze-thaw weathering

Mechanical weathering in which water enters cracks, freezes and expands, prising the rock apart; it is common in cold mountainous regions.

Waterfall formation

A waterfall forms where a river crosses a band of hard rock over softer rock; the soft rock erodes faster, creating a step and plunge pool.

Fold mountain

A mountain range formed when two continental plates collide and sedimentary strata buckle upwards, as in the Himalayas.

ITCZ

The Intertropical Convergence Zone, a belt of low pressure near the equator where trade winds converge, producing heavy convectional rainfall that shifts with the seasons.

Relief rainfall

Rainfall caused when moist air is forced to rise over high land; it cools, condenses and falls on the windward slope, leaving a dry rain shadow behind.

Benguela Current

A cold ocean current flowing north along south-west Africa; it cools the air above it, suppresses rainfall and causes coastal fog in the Namib.

Climate versus weather

Weather is the short-term state of the atmosphere, while climate is the average weather of a place measured over 30 years or more.

Food chain

A sequence showing the transfer of energy from producers through herbivores to carnivores; energy is lost at each level, limiting chain length.

Natural increase

The rate at which a population grows because births exceed deaths, calculated as birth rate minus death rate, expressed per 1,000 people.

Push factor

A negative condition that encourages people to leave a place, such as war, drought, unemployment or poor services.

Population pyramid

A graph showing the age and sex structure of a population; a broad base indicates high birth rates, a narrow top indicates short life expectancy.

Settlement hierarchy

An ordering of settlements from hamlet to conurbation by size and the number of services; larger settlements offer higher-order, more specialised services.

Site and situation

Site is the actual land a settlement occupies, such as a river crossing; situation is its position relative to surrounding routes and resources.

Primary economic activity

Work that extracts raw materials directly from the earth, such as farming, fishing, forestry and mining.

Human Development Index

A composite measure of development combining life expectancy, education (years of schooling) and income per person; it ranges from 0 to 1.

GDP per capita

The total value of goods and services produced by a country in a year divided by its population, used as a rough measure of living standards.

Subsistence farming

Farming that produces just enough food for the farmer's family, using little capital or machinery and with little surplus for sale.

Sustainable development

Development that meets the needs of the present without compromising the ability of future generations to meet their own needs.

Renewable resource

A natural resource that is replenished by natural processes within a human lifetime, such as solar energy, wind, water and forests.

Desertification

The degradation of land in dry areas, caused by overgrazing, drought and poor irrigation, turning fertile land into desert-like conditions.

Environmental impact assessment

A formal study carried out before a major project to predict its effects on the environment and to propose measures that reduce harm.

Community conservancy

An area in Namibia where local communities manage wildlife and tourism on their land, sharing the income and gaining rights to use wildlife.

Map scale

The ratio between distance on a map and distance on the ground; on a 1:50,000 map, one centimetre represents half a kilometre.

Contour line

A line on a map joining points of equal height above sea level; closely spaced contours show steep slopes, widely spaced ones show gentle slopes.

Six-figure grid reference

A method of locating a point on a map using three digits for the easting and three for the northing, giving a position within a grid square.

Gradient

The steepness of a slope, calculated as vertical interval divided by horizontal distance and expressed as a ratio or percentage.

Namib Desert

A narrow, extremely arid desert along Namibia's Atlantic coast, kept dry by the cold Benguela Current and characterised by fog, dunes and sparse vegetation.

Orange River

The longest river in South Africa, forming Namibia's southern border; it supplies irrigation water and supports hydro-electric schemes.

Etosha Pan

A large salt pan in northern Namibia, the centre of Etosha National Park, which fills with shallow water in good rainy seasons and attracts wildlife.

Namibian mining

A key sector producing uranium, diamonds, copper, zinc and gold; it earns foreign currency but is sensitive to world mineral prices.