BGCSE Geography (Botswana General Certificate of Secondary Education) cheat sheet

The Bahamas is an archipelago of about 700 islands and 2,000 cays on two shallow carbonate platforms (Great Bahama Bank and Little Bahama Bank), separated by deep channels such as Tongue of the Ocean.

Relief is low: Mount Alvernia on Cat Island, about 63 m, is the highest point; most islands are less than 30 m above sea level.

Limestone (oolitic and reef-derived) underlies nearly all land; karst features include blue holes, caves, sinkholes and solution valleys.

Climate is tropical savanna (Aw) with a wet season roughly May-November and a dry season December-April; northeast trade winds dominate.

Hurricanes (June-November, peak August-October) bring storm surge, coastal erosion and saline intrusion into freshwater lenses.

Fresh water sits in thin Ghyben-Herzberg lenses floating on denser seawater; overpumping causes saline intrusion.

Mangrove swamps, seagrass beds and coral reefs form linked coastal ecosystems that buffer wave energy and serve as nurseries.

Rainfall decreases southeastward (about 1,300 mm in Nassau, under 800 mm in Great Inagua); Inagua and Mayaguana are driest.

Population is about 400,000, with roughly 70% on New Providence and most of the remainder on Grand Bahama and Abaco.

Settlement is coastal and nucleated: nearly every town sits on a harbour, bay or leeward shore for shelter and trade.

Family Island out-migration to Nassau and Freeport followed the decline of sponging, wrecking and small-scale farming after the 1950s.

Emigration to the USA (Florida, New York) and return migration shape household structure; remittances supplement incomes.

The population is predominantly of African descent; significant Haitian-born and Haitian-descended communities exist, especially on New Providence, Grand Bahama and Abaco.

Nassau's Over-the-Hill district dates from post-emancipation (1838) freed-slave settlements; many Family Island settlements are Loyalist-era (1780s).

Population growth is slowed by low fertility and net emigration; the dependency ratio is affected by a young base and older return migrants.

Census data (most recently 2022) record population by island, sex, age group and household, used for planning and constituency boundaries.

Tourism and offshore financial services together generate the bulk of GDP and employment; tourism alone accounts for roughly half of GDP.

Stopover visitors outspend cruise passengers many times over; cruise arrivals dominate by number but contribute little per head.

Nassau (Cable Beach, Paradise Island) and Freeport are the main tourism nodes; Exuma, Abaco, Eleuthera and Harbour Island serve upscale and boating markets.

Hurricane Dorian (2019) destroyed much of Abaco and Grand Bahama, illustrating dependence on a narrow, climate-exposed economic base.

Agriculture is small-scale: citrus (Abaco, Andros), onions, tomatoes, pineapples and fishing (crawfish/spiny lobster, conch, scale fish).

The Bahamas imports most food and fuel, so the visible trade balance is chronically in deficit; services and remittances offset it.

Development indicators are high-income (GDP per capita above US$25,000), but income inequality, high electricity costs and narrow export base are constraints.

The Family Islands depend on fishing, small tourism, government employment and remittances; diversification is limited by transport and market size.

Scale: representative fraction (1:50,000) converts map to ground by multiplying; 1 cm on map at 1:50,000 equals 0.5 km on the ground.

Grid references: eastings (vertical lines) are read before northings (horizontal lines); a six-figure reference locates a 100 m square on a 1:50,000 map.

Contours join points of equal height; closely spaced contours mean steep slope, and V-shapes pointing uphill mark valleys.

Bearing is measured clockwise from grid north with a protractor or compass; back bearing differs by 180 degrees.

Cross-sections are drawn by transferring contour heights along a transect and joining them; vertical exaggeration = horizontal scale / vertical scale.

Fieldwork sampling: random, systematic (line or belt transect) and stratified; quadrats estimate vegetation cover, flow meters measure stream velocity.

Data presentation: bar and line graphs for totals and trends, pie charts for proportions, scatter graphs for correlation, choropleth and isoline maps for spatial patterns.

Fieldwork sequence: aim/hypothesis, method, risk assessment, data collection, presentation, analysis, conclusion and evaluation.

Insolation is concentrated at the equator because the sun's rays strike at a high angle; this drives the global pressure and wind belts.

Air moves from high to low pressure; the Coriolis effect deflects it right in the Northern Hemisphere, giving the northeast trades in the Bahamas.

Low pressure at the Intertropical Convergence Zone produces rising air, heavy convectional rain and thunderstorms.

A hurricane needs sea-surface temperature above about 27 degrees C, low wind shear and at least 5 degrees latitude from the equator for Coriolis spin.

Tropical rainforest has layered structure (canopy, understorey, ground layer), high biodiversity and rapid nutrient cycling in thin soils.

Mangrove adaptations include prop roots, salt tolerance and viviparous seedlings; they colonise sheltered, muddy, low-energy shores.

Coral reefs need warm (20-29 degrees C), clear, shallow, well-lit water and cannot tolerate silt or fresh water.

Climate graphs plot mean monthly temperature (line) and rainfall (bars); the wet season shows rainfall above 60 mm in most tropical stations.

Long profile: a river is steep and erosive in its upper course (V-shaped valleys, waterfalls, rapids) and depositional in its lower course (floodplain, levees, delta).

Erosion processes are hydraulic action, abrasion, attrition and solution; transportation is traction, saltation, suspension and solution.

The Hjulstrom relationship: larger particles need higher velocity to entrain, but fine clays need higher velocity to erode than to keep in suspension.

Wave energy depends on fetch, wind speed and duration; constructive waves are low and long, destructive waves are high and steep.

Longshore drift moves sediment in a zigzag along the shore; groynes trap sediment up-drift and starve the beach down-drift.

Headlands and bays form where resistant and weak rock alternate; wave refraction concentrates energy on headlands.

Coral reefs are classified as fringing, barrier and atoll; the Bahamian platform has extensive fringing and patch reefs behind barrier islands.

Beach, spit, tombolo, barrier island, dune and lagoon are depositional landforms; cliff, wave-cut platform and sea cave are erosional.

Earth's structure: crust, mantle, outer core (liquid) and inner core (solid); the lithosphere is broken into plates that move on the asthenosphere.

Divergent boundaries create mid-ocean ridges and rift valleys; convergent boundaries produce subduction zones, trenches, island arcs and fold mountains; transform boundaries produce faults.

The Bahamas lies on the North American Plate, far from a plate margin, so it is aseismic and has no volcanoes; its landforms are depositional and karstic.

Limestone is a sedimentary rock formed from calcium carbonate shells and ooids; it is permeable, so water dissolves it to form karst.

The rock cycle links igneous (cooled magma), sedimentary (deposited and lithified) and metamorphic (heat and pressure) rocks.

Weathering in the Bahamas is dominated by chemical solution (carbonation) and biological activity; freeze-thaw is absent in the tropics.

Karst landforms include sinkholes, caves, stalactites, stalagmites, blue holes, dolines and dry valleys.

Soil formation depends on parent material, climate, organisms, relief and time; thin, stony, alkaline soils over limestone are typical.

Natural increase = birth rate minus death rate; net migration adds or subtracts from it to give total population change.

Population pyramids show age-sex structure: broad base means high fertility, narrow base means ageing or low fertility.

The demographic transition has four stages: high stationary, early expanding, late expanding and low stationary.

Rural-urban migration is pushed by limited land and services and pulled by jobs, education and healthcare in towns.

Settlement site factors are water supply, flat land, fertile soil, defence, shelter and bridging points; situation relates to routes and resources.

Settlement patterns are dispersed, nucleated and linear; nucleation occurs where resources or services cluster.

Dependency ratio = (under 15 + over 64) / working-age population x 100.

Overpopulation is judged relative to resources, not density alone; the Bahamas has high density in Nassau but low density overall.

Inputs-processes-outputs model: inputs (seed, labour, fertiliser), processes (ploughing, planting, harvesting) and outputs (crops, profit).

Intensive farming uses high inputs per hectare; extensive farming uses low inputs per hectare, as in Bahamian pine and scrub grazing.

Shifting cultivation and commercial plantation agriculture differ in scale, capital and labour; the Bahamas relies on imports for staples.

Industry is classified as primary (extractive), secondary (manufacturing) and tertiary (services); the Bahamas is dominated by tertiary activity.

Industrial location factors: raw materials, power, transport, labour, market, capital and government policy.

Sustainable resource management balances use and renewal; overfishing of conch and lobster and overpumping of groundwater are local examples of overuse.

Renewable resources (solar, wind, fish, timber) can be replenished; non-renewable resources (oil, minerals) cannot.

Environmental impact assessment identifies likely effects of development before approval; marine protected areas and fishing seasons limit catch.

Urbanisation is the rising proportion of a population living in towns; it is driven by natural increase and rural-urban migration.

Urban land-use models (Burgess concentric zones, Hoyt sectors) describe zones of similar function around a centre; Nassau shows a commercial core with expanding suburbs.

Urban problems include congestion, informal housing, waste disposal, water supply and coastal pollution; responses include zoning, planning and public transport.

Development is measured by GDP per capita, HDI (life expectancy, education, income) and the Gini coefficient for inequality.

The Brandt line separates richer from poorer nations; the Bahamas is classified as high-income but with a narrow export base.

Global interdependence: trade, tourism demand, foreign investment, remittances and aid link the Bahamas to the USA, Canada and Europe.

Terms of trade compare export and import prices; countries exporting few goods face volatile income.

Sustainable development meets present needs without compromising future generations; Small Island Developing States face climate vulnerability.