NSSCO Geography 6137 cheat sheet

Earth's layers: crust (5-70 km thick), mantle (to ~2,900 km), outer core (liquid iron-nickel, generates the magnetic field), inner core (solid iron-nickel, ~5,100-6,370 km depth).

Crust types: continental crust is granitic, thick (30-70 km) and less dense (~2.7 g/cm³); oceanic crust is basaltic, thin (5-10 km) and denser (~3.0 g/cm³), so oceanic crust subducts beneath continental crust.

Plate boundaries: divergent (plates separate, new crust forms, e.g. Mid-Atlantic Ridge), convergent (subduction or collision, e.g. Andes, Himalaya), transform (plates slide past, e.g. San Andreas Fault).

Rock cycle: igneous rocks crystallise from magma/lava (granite intrusive, basalt extrusive); sedimentary rocks form by compaction and cementation of deposited sediment (sandstone, limestone); metamorphic rocks form when existing rocks are altered by heat and pressure (marble from limestone, slate from shale).

Weathering: mechanical (freeze-thaw, exfoliation, salt crystallisation) breaks rock physically; chemical (carbonation, oxidation, hydrolysis) alters its composition. Both are in situ; erosion then transports the material.

River landforms: V-shaped valleys and waterfalls in the upper course, meanders and floodplains in the middle, deltas and levees in the lower course. Deposition occurs where velocity falls.

Wind action in deserts produces yardangs, zeugen, barchan dunes and deflation hollows; water, though rare, is often the dominant erosional agent in semi-arid Namibia.

Fold mountains form where two continental plates collide and strata buckle; faulting produces horsts (uplifted blocks) and rift valleys (downfaulted blocks).

Weather is the short-term state of the atmosphere; climate is the average of weather over 30 years or more.

Insolation is strongest near the equator because solar rays strike at a high angle and pass through less atmosphere; it is weakest at the poles.

Pressure belts: equatorial low (ITCZ), subtropical highs at about 30° N/S, subpolar lows at about 60° N/S, polar highs. Winds blow from high to low pressure, deflected by the Coriolis force.

The ITCZ shifts with the overhead sun, giving tropical wet-and-dry climates (Aw) a single rainy season; Namibia's rainy season is roughly November to March.

Cold ocean currents cool adjacent air and stabilise it, suppressing rainfall; the cold Benguela Current keeps the Namib coast arid and foggy.

Relief rainfall occurs when moist air is forced to rise over mountains; the windward slope is wet, the leeward slope (rain shadow) is dry.

Ecosystem components: producers (plants), consumers (herbivores, carnivores), decomposers; energy flows through food chains and is lost at each trophic level, while nutrients cycle.

Biomes of Southern Africa include savanna, grassland, desert (Namib), semi-desert (Karoo) and fynbos; vegetation adapts to rainfall, temperature and fire.

Birth rate, death rate and natural increase: natural increase (%) = (birth rate − death rate) ÷ 10. Migration adds or subtracts from this to give total population change.

Population pyramid shapes: broad base and narrow top indicate high birth and death rates (stage 2 of the demographic transition); a narrow base indicates falling fertility and an ageing population.

The demographic transition model has five stages: high fluctuating, early expanding, late expanding, low fluctuating, and decline.

Push factors drive people from a place (war, drought, unemployment); pull factors attract them (jobs, safety, services).

Site factors for settlement: water supply, flat land, fertile soil, defence, bridging point. Situation factors relate to routes, trade and surrounding resources.

Settlement hierarchy: hamlet, village, town, city, conurbation. Higher-order settlements offer more specialised, less frequent services with larger thresholds and ranges.

Urban land-use models: the Burgess concentric-zone model and Hoyt sector model describe land use by distance from the CBD; land value falls outward from the centre.

Rapid urbanisation in developing countries can outpace housing and services, producing informal settlements (shacks) with insecure tenure.

Sectors: primary (extraction - farming, mining, fishing), secondary (manufacturing, processing), tertiary (services), quaternary (knowledge and research).

The Clark-Fisher model shows employment shifting from primary to secondary to tertiary as economies develop.

Development indicators: GDP per capita, life expectancy, literacy rate, infant mortality, Human Development Index (HDI combines income, education and health).

GNP = GDP + net income from abroad. Per-capita figures are calculated by dividing the total by population.

The Brandt line separates the wealthier 'North' from the poorer 'South'; the terms LEDC/MEDC or developing/developed are used instead today.

Types of farming: subsistence vs commercial, intensive vs extensive, arable vs pastoral. Nomadic pastoralism and ranching are extensive systems suited to dry areas.

Industry location factors: raw materials, power, water, labour, transport, market, capital, government policy.

Tourism and mining are major earners for Namibia; both depend on infrastructure and are vulnerable to external demand shocks.

Renewable resources replenish naturally (solar, wind, water, forests); non-renewable resources are finite (coal, oil, minerals) and are depleted by use.

Sustainable development meets present needs without compromising the ability of future generations to meet theirs (Brundtland definition).

Resource management tools: quotas, licences, protected areas, recycling, environmental impact assessment (EIA), and integrated water resource management.

Water scarcity in dry regions is managed by dams, boreholes, pipelines, desalination and water harvesting; Namibia is a water-scarce country reliant on dams and the Okavango/Orange systems.

Deforestation causes soil erosion, loss of biodiversity and reduced carbon storage; replanting and controlled harvesting mitigate it.

Desertification is land degradation in drylands driven by overgrazing, drought and poor irrigation; it is combated by rotational grazing, windbreaks and terracing.

Pollution types: air (emissions, particulates), water (sewage, fertiliser runoff, mine effluent), land (solid waste), noise.

Conservation approaches include national parks, community conservancies, transfrontier parks and species protection; Namibia's conservancy model gives communities wildlife-use rights.

Scale: a representative fraction (1:50,000) means 1 unit on the map equals 50,000 of the same units on the ground, so 1 cm = 0.5 km.

Grid references: a four-figure reference gives the grid square (easting first, then northing); a six-figure reference locates a point within the square.

Contour lines join points of equal height. Close contours indicate steep slopes; widely spaced contours indicate gentle slopes.

Cross-sections: plot distance along the horizontal axis and height on the vertical axis, then join the points. Vertical exaggeration = vertical scale ÷ horizontal scale.

Bearings are measured clockwise from north, in three digits (e.g. 045°). Back bearing = bearing ± 180°.

Map symbols: blue for water, green for vegetation, brown for contours, black for buildings and boundaries, red for main roads.

Fieldwork sequence: define the aim, form a hypothesis, choose sampling (random, systematic, stratified), collect data, present it (graphs, maps), analyse and conclude.

Gradient = vertical interval ÷ horizontal distance, expressed as a ratio or percentage.

Namibia lies on the south-west coast of Africa, bordered by Angola, Zambia, Botswana, South Africa and the Atlantic Ocean; the capital is Windhoek.

The Namib Desert runs along the coast, backed by the Central Plateau; the Kalahari lies to the east. The cold Benguela Current causes coastal fog and aridity.

The Orange River forms the southern border and supplies water and hydro-electricity (e.g. at Ruacana on the Kunene and Hardap on the Fish River).

Namibia is a major producer of uranium, diamonds, copper, zinc and gold; mining is a leading export earner but vulnerable to world prices.

Agriculture is limited by low rainfall; livestock ranching (cattle, sheep, goats) dominates, with crop farming in the north.

The Okavango and Caprivi (Kwando-Linyanti) systems support wetlands and wildlife; the Etosha Pan is a large salt pan in the north.

Southern Africa's climate is influenced by the ITCZ, the subtropical high and the cold Benguela Current; rainfall decreases from east to west.

The region's economies are linked through SACU and SADC; migrant labour and trade in minerals and agricultural produce are significant.