WAEC SSCE - Geography - 2008

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Koppen used temperature and rainfall to classify the climates of the world.

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Mercury, the closest planet to the sun in our solar system, takes about 88 Earth days to complete one revolution or orbit around the sun. This means that it travels 88 days to make a full circle around the sun.

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The part of the earth where life exists is the biosphere. The biosphere is the portion of the Earth that supports life, including all living organisms and their interactions with each other and with the non-living parts of the Earth, such as the atmosphere, hydrosphere, and lithosphere. It includes all living things, from tiny bacteria to giant whales, and extends from the depths of the oceans to high in the atmosphere. The biosphere is where all the biological processes that sustain life occur, and it is essential to the survival of all living organisms.

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The answer is "ineffective publicity". This is because effective publicity is a key factor in promoting tourism and attracting tourists to a destination. The other options are favorable factors for tourism development in West Africa. Highlands, rocks and beaches provide scenic attractions, while abundant wildlife provides opportunities for nature-based tourism. Improved communication facilities facilitate the movement of tourists and provide access to information about tourist destinations. Therefore, ineffective publicity, which hinders the promotion and marketing of tourist destinations, is not a favorable factor for tourism development in West Africa.

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Afforestation is not a possible cause of soil erosion. Afforestation is the process of establishing a forest, or stand of trees, in an area where there was no forest. It can actually help prevent soil erosion as the trees and their roots help to hold the soil in place, reducing the effects of wind and water erosion. On the other hand, deforestation, bush burning, and over-grazing are all known causes of soil erosion. Deforestation removes trees, which can lead to increased soil erosion from wind and water. Bush burning destroys vegetation cover and exposes the soil, making it more vulnerable to erosion. Over-grazing removes the vegetation cover and exposes the soil, making it more susceptible to erosion by wind and water.

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A place where water issues out from the ground naturally is called a spring. Springs are formed when groundwater flows to the surface through an opening in the ground. The water that emerges from a spring may be heated or cooled, and may contain minerals that have been dissolved from rocks and soil. Springs are important sources of fresh water for many communities, and they also provide habitats for a wide variety of plants and animals.

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Isotherm is a line on a map connecting points having the same temperature. Similarly, an isobar is a line on a map connecting points having the same atmospheric pressure. Therefore, the correct answer is "isobar" because it is to pressure what isotherm is to temperature.

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The atmosphere is the blanket of gases that surrounds the Earth. It is an important resource for life on the planet. The gases in the atmosphere, such as oxygen and carbon dioxide, are essential for supporting life. The atmosphere also plays a role in regulating the temperature and weather patterns on Earth. Rain and wind are two examples of the resources that the atmosphere provides. They are both important for shaping the landscape and providing water for plants and animals. Vegetation, on the other hand, is not a resource of the atmosphere but rather a part of the biosphere, which refers to all living organisms on Earth. Therefore, the correct answer is vegetation.

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The answer is atmosphere. The atmosphere is the layer of gases that surrounds the Earth and is held in place by gravity. It is made up of different gases, including nitrogen, oxygen, carbon dioxide, and other trace gases. The atmosphere is important for supporting life on Earth, protecting us from harmful radiation, and helping to regulate the Earth's temperature.

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In the upper course of a river, one can find features such as waterfalls, rapids, V-shaped valleys, interlocking spurs, and gorges, which are usually narrow and steep-sided. An ox-bow lake, on the other hand, is typically found in the lower course of a river where the river meanders and bends. Cataracts, meanwhile, are found in rivers that flow through rocky areas and can be found in both the upper and lower courses. Therefore, the correct answer is "ox-bow lake."

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The region on the earth's surface popularly referred to as the land of midnight sun is the north of the Arctic Circle. This is because at latitudes north of the Arctic Circle (approximately 66.5 degrees north), there are periods of continuous daylight during the summer months. This occurs because the tilt of the Earth's axis means that the sun does not set below the horizon during this time. As a result, areas such as Norway, Sweden, Finland, and parts of Russia, which are located north of the Arctic Circle, experience the "midnight sun" phenomenon during the summer solstice.

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The environmental hazards are the natural phenomena or human activities that cause harm to the environment and human health. Flooding and vulcanicity are environmental hazards because they can cause damage to property and life. Deforestation is also an environmental hazard because it can lead to soil erosion, loss of biodiversity and other negative impacts on the environment. However, afforestation is not an environmental hazard, as it refers to the process of planting trees and creating forests, which helps to mitigate the negative effects of deforestation and other environmental hazards. Therefore, the answer is "afforestation".

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Dissolved fertilizers are water pollutants. When fertilizers are applied to land, some of the nutrients dissolve in rainwater and are carried into streams and other water bodies. The excess nutrients, especially nitrogen and phosphorus, can cause an overgrowth of algae and other aquatic plants, leading to a process called eutrophication. This process can reduce oxygen levels in the water, leading to the death of fish and other aquatic organisms. Aquatic animals, shrimps, and water plants are not necessarily water pollutants but are part of the aquatic ecosystem. However, their presence and abundance can be indicators of water quality and the health of the ecosystem.

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The description 'crescentic or moon-shaped and occurs transversely to the direction of the prevailing wind' refers to a barchan. A barchan is a type of sand dune that is crescent-shaped and has horns that point in the downwind direction. Barchans are formed by the action of wind, which blows sand particles across the desert floor and deposits them on the upwind side of the dune. As the sand accumulates, it forms the crescentic shape of the dune. Barchans migrate across the desert, with the horns pointing in the direction of the prevailing wind.

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A relative humidity of 100 percent means that air is saturated. Relative humidity is the ratio of the amount of moisture in the air to the maximum amount of moisture that can be held at a given temperature. When the air is holding the maximum amount of moisture that it can hold, it is considered to be saturated. Therefore, a relative humidity of 100 percent indicates that the air is fully saturated with moisture, and any further addition of moisture would result in condensation, such as dew or fog.

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Primary industries are those that are directly involved in the extraction and collection of natural resources from the environment. They include activities like farming, fishing, forestry, and mining. Out of the options given, processing is the only activity that does not belong to primary industries. Processing involves converting raw materials obtained from primary industries into finished or semi-finished products that can be sold to consumers. Therefore, processing is a secondary industry. So, the correct answer is: processing.

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The busiest and most important ocean route in the world is the North Atlantic. This is because it connects the major economic regions of North America and Europe, with large volumes of trade and commerce passing between them. Additionally, the North Atlantic is also an important route for travel and transportation, with numerous passenger liners and cargo ships plying its waters. The route is also important for military purposes, particularly during times of war or conflict, as it provides a strategic gateway between the two continents.

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The correct answer is "decreased production". Transportation plays a significant role in economic development through various means, such as the movement of people and goods, creating employment opportunities, opening up new markets, promoting international trade, and enhancing cultural and social exchanges. However, decreased production cannot be considered as a contribution of transportation to economic development as it is a negative impact on the economy. Transportation is intended to facilitate the movement of goods and people, which should lead to increased production, not decreased production.

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Savanna regions are characterized by long dry seasons, so trees in this region have adapted to survive these harsh conditions. The adaptation that is not listed among those that enable trees to survive the long dry season is "shallow roots." This is because shallow roots cannot access deep soil moisture during the dry season, making it difficult for the tree to survive. The other adaptations, such as long taproots, thick barks, and thin leaves, are all beneficial for the trees in the savanna region. Long taproots enable the trees to access deep soil moisture during the dry season, while thick barks protect the trees from fires that are common in savanna regions. Thin leaves reduce water loss through transpiration, which is important in a region where water is scarce.

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When the moon comes in between the earth and the sun, a solar eclipse occurs. The moon blocks the light from the sun, casting a shadow on the earth. Solar eclipses can only occur during the new moon phase, when the moon is between the sun and the earth. The eclipse can be partial or total depending on the alignment of the sun, moon, and earth. During a total solar eclipse, the sun's outer atmosphere or corona is visible, and the sky becomes dark as if it were nighttime.

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A stalagmite differs from a stalactite in that a stalagmite starts from the floor of a cave while a stalactite starts from the roof of a cave. Therefore, the correct option is "starts from the floor of a cave". Stalagmites are formed by mineral deposits that accumulate on the floor of a cave over time, usually as a result of dripping water containing dissolved minerals. On the other hand, stalactites are formed by mineral deposits that accumulate on the roof of a cave and hang downward, also as a result of dripping water containing dissolved minerals.

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Population density is the number of people living in a particular area per unit of land area. To calculate the population density of a country, we divide the total population of the country by its land area. Population density = Total population / Land area In this question, the total land area of the country is given as 24,000 square kilometers and the population is 7,200,000. We can substitute these values in the above formula to find the population density. Population density = 7,200,000 / 24,000 Population density = 300 persons per km2 Therefore, the population density of the country is 300 persons per km2. The correct answer is: 300 persons per km2.

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Sedimentary rocks are usually **stratified**. Sedimentary rocks are formed by the accumulation of sedimentary materials such as minerals, organic matter, and rock fragments, which are then compacted and cemented together. These rocks are typically formed in layers or strata, with each layer representing a different period of deposition. The layers can often be seen as visible bands of different colors or textures, and they can provide important clues about the geological history of the area where they are found.

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The correct answer is "earthquake". An earthquake is not a form of mass movement, it is a sudden shaking or trembling of the Earth's surface caused by the movement of tectonic plates. Mass movement, on the other hand, is the downward movement of soil, rock, or other debris under the influence of gravity. The other options - landslide, rockslide, and talus creep - are all forms of mass movement, where soil, rock, or other materials move down a slope due to gravity. Overall, mass movements can be caused by a variety of factors, including the angle of the slope, the type of material involved, the amount of water present, and the presence of vegetation or other stabilizing factors.

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The core of the Earth is a layer located at the center of the Earth. It is the innermost part and is made up of two parts, the inner core and the outer core. The inner core is solid while the outer core is liquid. Another name for the core of the Earth is barysphere. The term barysphere is derived from the Greek word 'barys' which means heavy. This is because the core is the heaviest part of the Earth and contains a large proportion of the Earth's total mass.

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One of the major problems of manufacturing industries in Tropical Africa is inadequate raw materials. This means that manufacturing industries in this region often face a shortage of the necessary raw materials needed for production. This can be due to a number of factors, such as poor infrastructure, limited agricultural productivity, and a lack of investment in extractive industries. As a result, manufacturing industries in Tropical Africa often have to rely on imported raw materials, which can be expensive and further limit their ability to compete in the global marketplace.

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A fold mountain is a type of mountain formed from the folding of rocks due to compressional forces in the Earth's crust. One of the features of a fold mountain is an anticline, which is an upward arching fold of rock layers, resembling an arch or a dome. This is in contrast to a syncline, which is a downward folding of rock layers. Anticlines and synclines can alternate in fold mountain chains, creating a series of peaks and valleys. Therefore, the correct option is "anticline."

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(a) Four advantages of rural-urban migration:

• Supply of labour to towns: migrants provide the workforce needed for industries, construction and services in the urban areas.
• Higher incomes and remittances: migrants earn better wages and send money home, improving the welfare of rural families.
• Reduction of pressure on rural land: movement of people out of villages reduces population pressure on farmland and other rural resources.
• Acquisition of skills and exposure: migrants acquire education, skills and new ideas in the town, some of which they later transfer to the rural areas.

(b) Four effects of rural-urban migration on urban areas:

• Overcrowding and housing shortage: rapid population increase leads to congestion and the growth of slums and shanty settlements.
• Unemployment and underemployment: more people arrive than the town can employ, raising unemployment.
• Pressure on services and infrastructure: water, electricity, schools, hospitals, roads and sanitation become overstretched.
• Increase in social problems: crime, prostitution, traffic congestion and environmental pollution rise (though the labour force and market also expand).

(c) Two measures to check rural-urban migration:

• Rural development: provide the countryside with amenities such as good roads, electricity, water, schools, hospitals and industries so that life there is attractive.
• Creation of rural employment and improved agriculture: establish agro-based industries and modernise farming so that jobs and good incomes exist in the villages (siting of industries and administrative functions in rural areas).

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(a) The three stages of development of a river along its course:

• Youthful (upper) stage: here the river is near its source in the highlands. The gradient is steep and the river flows swiftly, so it erodes chiefly vertically (downward). It carves a deep, narrow V-shaped valley with interlocking spurs, waterfalls, rapids, gorges and potholes. The channel is narrow and turbulent and the load is coarse.
• Mature (middle) stage: the gradient is gentler and the river has a larger volume from tributaries. Erosion is now both vertical and lateral (sideways), so the valley widens. The river begins to meander, forming river cliffs on the outer bends and slip-off slopes on the inner bends, and a wider valley floor develops.
• Old (lower) stage: near the mouth the gradient is very gentle and the river flows sluggishly over a broad, flat flood plain. Lateral erosion and deposition dominate: the river forms large meanders, ox-bow lakes, levees, and finally deposits its load to build a delta or estuary at the sea.

(b) Two ways in which rivers are important to man:

• Water supply and irrigation: rivers provide water for drinking, domestic use, industry and for irrigating farmland in dry areas.
• Hydro-electric power and transport: fast-flowing sections are dammed to generate electricity, while navigable stretches serve as cheap routeways for boats and for fishing. (Rivers are also important for fishing and fertile flood-plain soils.)

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(a) Local time versus standard time

(b) Longitude of Town B

Latitude is the same, so it does not affect the calculation. Use the difference in local time between the two towns.

Town A (70 degrees E): local time = 7.46 p.m. = 19:46.
Town B: local time = 5.30 a.m. = 05:30.

Time difference:

Convert to minutes: \(14 \times 60 + 16 = 856\) minutes.

Since 1 degree of longitude = 4 minutes of time, the longitude difference is:

Town B's local time (05:30) is earlier (behind) Town A's (19:46), so Town B lies to the west of Town A.

Longitude of B = \(70^{\circ}E - 214^{\circ}\).

A negative value means we have crossed the 0 degree meridian into western longitudes:

Town B lies on longitude \(144^{\circ}W\).

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(a) Three factors that favour lumbering in Cote d'Ivoire (or Zaire/DR Congo):

• Extensive dense tropical rain-forest: a large area is covered by rain-forest containing valuable hardwoods such as mahogany, obeche, iroko and sapele, giving a big supply of timber.
• Hot, wet equatorial climate: high temperatures and heavy, well-distributed rainfall promote rapid and continuous tree growth all year.
• Navigable rivers and improving transport: rivers, together with roads, railways and ports (Abidjan, San Pedro; or the Congo river system), make it possible to move heavy logs to sawmills and to the coast for export; a market abroad and available labour also help.

(b) Method of lumbering in Cote d'Ivoire:

Lumbering is carried out by selective felling because the valuable trees are scattered among many worthless ones. First the forest is surveyed and the mature, valuable trees are marked. Access roads and tracks are cut into the forest. The selected trees are felled with power saws (chain-saws) and the branches removed. The heavy logs are dragged (skidded) to a loading point by tractors or winches, then loaded onto trucks or floated down rivers to the sawmills at the coast, where they are sawn into planks or processed into plywood and veneer for local use and export.

(c) Four problems associated with lumbering in Africa:

• Mixed nature of the forest: valuable trees are widely scattered among many useless species, making felling and extraction costly.
• Difficulty of transport: the heavy logs and the dense, wet forest with few roads make movement of timber slow and expensive.
• Pests, diseases and dense undergrowth: tsetse fly, mosquitoes and thick undergrowth hamper work in the forest, and some timber is attacked by pests.
• Shortage of skilled labour and capital, and deforestation: lack of trained workers and machinery slows the industry, while over-cutting leads to forest destruction and soil erosion.

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(a) Light and heavy industries:

• Two light industries: textile (garment) manufacturing; soap and cosmetics manufacturing (also food and beverage processing, electronics assembly).
• Two heavy industries: iron and steel manufacturing; cement manufacturing (also petroleum refining, shipbuilding, heavy machinery).

(b) Four factors an industrialist must consider before locating an industry:

• Availability of raw materials: the industry should be near its raw materials, especially where the material is bulky, heavy or perishable, to cut transport costs.
• Source of power/energy: a cheap and reliable supply of power (electricity, coal, oil, gas) is needed to run the machines.
• Supply of labour: nearness to a large pool of skilled and unskilled workers is important.
• Market: nearness to the market reduces the cost of distributing finished goods, especially bulky or fragile products.
• Transport and capital: good roads, rail, ports and adequate finance are also essential (water supply and land are further considerations).

(c) Four contributions of manufacturing industries to the economy:

• Employment: factories provide jobs for many people, raising incomes and standards of living.
• Increased national income and foreign exchange: manufactured goods add value and, when exported, earn foreign exchange for the country.
• Reduction of imports: local manufacturing of goods reduces dependence on imports and saves foreign exchange (import substitution).
• Development of infrastructure and other sectors: industry stimulates the growth of roads, power, banking and towns, and provides a market for agricultural and mineral raw materials.

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(a) Five factors that contribute to the development of tourism in Nigeria:

• Attractive natural features: waterfalls, hills and highlands (Assop Falls, Obudu Ranch, Jos Plateau), beaches (Bar Beach, Badagry), and warm sunny climate attract visitors.
• Wildlife and game reserves: national parks such as Yankari and Kainji Lake attract tourists interested in wildlife and safari.
• Rich cultural heritage and festivals: the Argungu fishing festival, Osun-Osogbo, Durbar, Eyo and other festivals, plus historic sites and museums, draw tourists.
• Good transport and communication: airports, roads and improved communication make tourist centres accessible.
• Availability of accommodation and government support: hotels, and government provision of infrastructure and promotion through tourism boards, encourage the industry (peace and security are also essential).

(b) Five contributions of the tourist industry to economic development:

• Foreign exchange earnings: money spent by foreign tourists earns valuable foreign exchange for the country.
• Employment: tourism creates jobs in hotels, transport, catering, guiding and handicrafts.
• Development of infrastructure: roads, airports, water and electricity are provided to serve tourist centres, benefiting the whole area.
• Market for local goods and crafts: tourists buy local craft and food, boosting local industries and farmers' incomes.
• Government revenue and regional development: taxes, park fees and hotel charges add to government revenue, and tourism spreads development to rural and previously backward areas.

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(a)(i) Difference between Erosion and Mass movement:

Erosion is the wearing away and removal of rock waste from one place to another by a moving transporting agent such as running water, wind, ice or waves. Mass movement (mass wasting) is the down-slope movement of rock waste and soil under the direct pull of gravity, without a separate transporting agent carrying the material away.

(a)(ii) Two features each:

• Features of river erosion: waterfalls and rapids; V-shaped valleys and gorges (also potholes, river cliffs).
• Features of mass movement: landslides; soil creep terracettes (also scree/talus slopes, slumps, mudflows).

(b) Factors that affect mass movement:

• Gradient (steepness) of slope: the steeper the slope, the stronger the pull of gravity down-slope and the faster and more likely the movement.
• Water content: water adds weight and lubricates the material, reducing friction; saturated soil moves easily as mudflows and slumps, so heavy rain triggers movement.
• Nature of the material: loose, unconsolidated or weathered material moves more readily than solid, coherent rock; the size and cohesion of particles matter.
• Vegetation cover: plant roots bind the soil and hold it in place, so bare slopes are far more prone to movement than well-vegetated ones.
• Underlying rock structure: where rock layers dip in the same direction as the slope, and along planes of weakness (joints, bedding), sliding is encouraged.
• Human activity and earth tremors: undercutting slopes for roads or building, overloading, and vibrations from earthquakes or blasting can set off movement.

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(a) Outline map of Africa showing the three climatic regions

The outline map below shows the position of each region asked for. The Tropical (savanna) Climatic region lies as two belts to the north and south of the equatorial zone; the Hot Desert Climatic region covers the Sahara in the north and the Kalahari/Namib in the south-west; and the Warm Temperate Eastern Margin Climatic region occupies the south-eastern coast of southern Africa (the Natal coast).

(b) Three characteristics of the Tropical Climate

1. Distinct wet and dry seasons. There is a single well-marked rainy season, with a peak about July, when the moist tropical maritime (South-West) winds blow, and a long dry season when the dry, dusty tropical continental (North-East trade / harmattan) winds blow.
2. High temperatures all year with a large annual range. Mean monthly temperatures stay high, between about \(21^\circ\mathrm{C}\) and \(32^\circ\mathrm{C}\), the hottest period coming just before the rains; the annual range of temperature is larger than in the equatorial zone.
3. Moderate, mainly convectional rainfall that decreases away from the Equator. Total annual rainfall averages about \(75\ \mathrm{cm}\) (\(750\ \mathrm{mm}\)), ranging from roughly \(60\ \mathrm{cm}\) to \(150\ \mathrm{cm}\); it falls chiefly as heavy convectional showers in the summer months and decreases from the equatorial borders towards the desert margins. Relative humidity is high (about 60-80%) in the wet season but low (about 20-40%) in the dry season.

(c) Three ways the vegetation (savanna) has adapted to the climate

1. Trees are deciduous and shed their leaves in the dry season to cut down water loss through transpiration; the vegetation is therefore seasonal, green in the rains and brown in the dry season.
2. Plants store water and reach deep water. Some trees, such as the baobab, develop swollen, bulbous trunks that store water, while many have long tap roots that reach down to underground water during the dry season.
3. Protective leaves, bark and root systems. Trees have thick, fire-resistant bark and narrow, thorny or waxy leaves that reduce transpiration, while the tall coarse grasses survive the dry season and annual bush burning as resistant underground roots and seeds, sprouting again with the first rains.

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(a) Four ways the physical setting of the Sokoto plains has influenced economic activities:

• Extensive flat plains and fertile fadama (flood-plain) soils have encouraged crop farming, especially of guinea corn, millet, rice, wheat and vegetables, particularly in the river valleys.
• The semi-arid (Sudan/Sahel) climate with a long dry season and open grassland favours livestock rearing (cattle, sheep, goats) and has made the area a leading grazing and cattle-trading region.
• The seasonal rivers (Sokoto and Rima) and their fadama land support dry-season irrigation farming and fishing.
• The dry climate and abundant sunshine favour the growing of cotton and groundnuts, which feed local textile weaving, dyeing, tanning and other agro-based crafts.

(b) Four problems of development facing the region:

• Unreliable rainfall and drought: the low and variable rainfall causes crop failure and shortage of water for people and animals.
• Poor soils and desertification: in places soils are thin and sandy, and advancing desert and soil erosion reduce farmland.
• Inadequate infrastructure: shortage of good roads, electricity, water supply and industries limits development.
• Population pressure and overgrazing: heavy grazing and farming degrade the land, and there is limited employment outside agriculture.

(c) Two ways any of these problems could be solved:

• Provision of irrigation and dams (for example the Bakolori and Goronyo dams) to store water and support farming through the dry season, tackling the water-shortage problem.
• Afforestation and shelter-belts to check desert encroachment and soil erosion, and improved farming methods to conserve the soil.

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(a) Outline of the map reduced to a scale of 1:300,000

The required scale (1:300,000) is one-third of the original scale (1:100,000). Therefore every length taken from the extract is drawn one-third of its size, while the shape, orientation and relative positions are kept exactly the same. The original frame of 36.6 cm is reduced to \(\tfrac{1}{3}\times 36.6 = 12.2\text{ cm}\), so the outline is a square of about 12.2 cm by 12.2 cm. On this outline the settlements of Lariski and Wuna Dole are each marked with a small circle and named, River Lakau is drawn as a single line with an arrow showing its direction of flow (downstream, from higher to lower ground towards its confluence), and the 1,100 ft contour is traced and labelled.

(b) Actual distance along the railway line from the bridge near Zangoma to the bridge along River Gaji

A thread is laid along the railway line, following every bend from the bridge near Zangoma to the bridge along River Gaji, then straightened against the linear scale and read off.

• Map measurement = 25 cm
• Map scale = 1 : 100,000, so 1 cm on the map represents 100,000 cm = 1 km on the ground.

The actual distance along the railway line is 25 km.

(c)(i) Three occupations of the people (with map evidence)

(Other supportable occupations include teaching, shown by the schools; transportation, shown by the roads and railway; and fishing, shown by the many rivers.)

(c)(ii) Most important settlement

Bara is the most important settlement in the mapped area. This is because it has a market and a school, and it is a nodal settlement where several roads and the railway line meet. These functions make it the chief centre of trade, services and communication in the area, so it attracts and serves the surrounding population more than any other settlement.

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Appearance and mode of formation of two landforms (any two required):

(a) Delta

• Appearance: a low, flat, triangular or fan-shaped plain of alluvium built out at the mouth of a river, split by numerous branching channels called distributaries, with swamps and mud-flats between them. The name comes from the Greek letter delta (\(\Delta\)).
• Mode of formation: as a river reaches its mouth its velocity is checked by the standing water of a sea or lake, so it can no longer carry its load. The river deposits its sediment (coarse first, then fine). Where the sea is shallow, tides and currents are weak and the sediment load is large, deposition builds up faster than it can be removed. The deposits accumulate, force the river to divide into distributaries, and gradually extend the land seaward as a delta, for example the Nile and Niger deltas.

(b) Block mountain (horst)

• Appearance: an upstanding block of land with steep, often straight fault-scarp sides and a comparatively flat top, standing above the surrounding lowland; adjacent sunken blocks form rift valleys or basins.
• Mode of formation: tensional (or compressional) forces in the crust produce parallel faults (lines of fracture). When the land between two faults stands up while the blocks on either side sink, or the central block is pushed up, an upstanding block called a horst or block mountain results. Examples include the Ruwenzori and the Vosges.

(c) Rock pedestal (mushroom rock)

• Appearance: an isolated desert rock shaped like a mushroom or table, with a narrow, undercut base (stem) and a broader top.
• Mode of formation: in deserts, wind armed with sand grains blasts rock surfaces (abrasion). Because most sand is carried within about a metre of the ground, cutting is strongest near the base. The lower part is worn away faster than the top, and where softer rock lies below harder rock the base is undercut, leaving a narrow stem supporting a wider cap.

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(a) Four ways in which a town differs from a village:

(A town also has a wider sphere of influence and a more complex social structure than a village.)

(b) Four functions a village may perform for a town (with examples):

• Supply of food: surrounding villages produce foodstuffs (yam, cassava, vegetables, livestock) that feed the town, for example villages around Ibadan feeding the city.
• Supply of raw materials: villages provide agricultural and forest raw materials (cotton, cocoa, timber) for the town's industries.
• Supply of labour: villagers migrate to work in the town's factories, markets and construction, providing much of the urban workforce.
• Provision of dormitory (residential) and recreational space: nearby villages serve as dormitory settlements where town workers live, and as places for weekend recreation and land for expansion; they also serve as a market for the town's manufactured goods.

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(a) Outline map of Nigeria showing the railway line and mineral areas

The sketch map below shows the outline of Nigeria with (i) the western railway line running from Lagos northward through Abeokuta, Ibadan, Ilorin and Jebba to Minna, and (ii) one producing area each of limestone, coal, columbite and gold.

Key to the map:

• Railway (Lagos-Minna): the western trunk line, Lagos → Abeokuta → Ibadan → Ilorin → Jebba → Minna.
• Limestone: Ewekoro (near Abeokuta, in the south-west).
• Coal: Enugu (south-east).
• Columbite: the Jos Plateau (central Nigeria).
• Gold: Ilesha (south-west).

(b) Method of mining columbite in Nigeria

Columbite occurs on the Jos Plateau as loose grains mixed with tin ore in the alluvial gravels ("wash") of the stream valleys, and is worked mainly by the open-cast (surface) method. The main steps are:

1. Removal of the overburden: the soil and rock covering the mineral-bearing gravel are stripped off, at times loosened with dynamite and other explosives.
2. Digging the ore: the exposed gravel is dug out using mechanical shovels, draglines and pick-axes, and a dragline gathers the ore-bearing gravel into heaps.
3. Washing and concentration: powerful water jets from a monitor (hydraulic gun) are directed at the heaps to break them into a slurry, which is passed over sluice boxes and jigs; the heavy columbite and tin settle out while the lighter sand and mud are washed away.
4. Drying and transport: the concentrate is dried and loaded onto trucks that convey it to the factory for smelting, and it is then conveyed by rail to the port for export.

(c) Three adverse effects of mining on the Jos Plateau (columbite/tin area)

1. Loss of farmland and grazing land: stripping the overburden removes the topsoil and vegetation, leaving the land bare and infertile; farming and grazing land is destroyed and the agricultural labour force is reduced.
2. Derelict land, mining ponds and health hazards: abandoned open pits fill with stagnant water, breeding mosquitoes and drowning livestock and children; dust and poor conditions cause health problems such as asthma and lung and heart disorders.
3. Environmental degradation and pollution: loose spoil heaps are easily eroded, and silt and chemicals pollute streams and rivers, harming aquatic life and water supplies; whole settlements are displaced, sometimes leaving ghost towns behind.

Détails de la réponse

None

Détails de la réponse

The Warm Temperate Western Margin (Mediterranean) climate

(a) Location: it is found on the western sides of continents between about \(30^\circ\) and \(45^\circ\) north and south of the Equator. The main areas are the lands bordering the Mediterranean Sea (Spain, Italy, Greece, North Africa), central and southern California, central Chile, the Cape region of South Africa, and south-western and southern Australia.

(b) Climatic characteristics:

• Hot, dry summers: summer temperatures are high (about \(21^\circ C\) to \(27^\circ C\)) with clear, sunny skies, because the belt comes under the influence of the dry off-shore trade winds and high pressure.
• Warm, wet winters: rain falls mainly in winter (about \(500\ mm\) to \(750\ mm\)) when the westerlies and depressions move over the region; winters are mild, around \(10^\circ C\).
• Winter rainfall maximum and abundant sunshine: the dry summer and wet winter regime is the key feature, with bright sunshine for most of the year.

(c) Vegetation: the natural vegetation is drought-resistant scrub and woodland known as maquis (or chaparral, matorral). Plants are adapted to the summer drought: they have small, thick, leathery or waxy leaves, deep or wide roots, thick bark and thorns to reduce water loss. Evergreen oaks, olive, cork oak, pines, and aromatic shrubs such as lavender and rosemary are typical, together with grasses and bulbous plants that flower in the wet season.

(d) Human activities:

• Mediterranean agriculture: cultivation of citrus fruits (oranges, lemons), olives, grapes (viticulture) for wine, figs and vegetables; the sunny summers ripen the fruit.
• Irrigated farming and market gardening where summer water is available.
• Sheep and goat rearing on the poorer scrub land.
• Tourism and wine-making industries, favoured by the warm, sunny climate and attractive coasts.

Détails de la réponse

(a) Outline map of Africa

The sketch map below shows the outline of Africa with the required rivers and lakes correctly located and named.

The features shown on the map are:

(b) Five factors that limit the use of African rivers

1. Presence of cataracts, rapids and waterfalls: many African rivers, such as the Congo, plunge over rapids and falls (for example the Livingstone Falls), which interrupt navigation and make continuous water transport impossible.
2. Wide fluctuation in river volume (regime): most rivers depend on seasonal rainfall, so they carry very high water in the wet season and shrink or dry up in the dry season, making them unreliable for transport, irrigation and power generation all year round.
3. Silting and sandbars at the river mouths: heavy loads of sediment carried in suspension are deposited at the mouths, forming shallow deltas and sandbars that block the entry of ocean-going ships to inland ports.
4. Presence of water weeds such as water hyacinth: dense mats of floating weeds choke the channels, obstruct boats, harbour disease vectors and reduce the flow available for use.
5. Shallow beds and narrow, obstructed channels: many rivers have shallow beds, narrow channels and high suspended debris, so they cannot take large vessels and are difficult to keep clear for navigation.

Détails de la réponse

(a) Difference between weather and climate:

Weather is the condition of the atmosphere of a place at a particular time or over a short period (a day or a few days), described in terms of temperature, rainfall, wind, pressure, humidity and sunshine; it changes from hour to hour and day to day. Climate is the average weather conditions of a place taken over a long period, usually not less than 35 years. In short, weather is short-term and changeable while climate is the long-term average.

(b) Instruments used to measure the weather elements:

(c) How wind speed is measured and recorded:

Wind speed is measured with a cup anemometer. It consists of three or four hollow hemispherical cups mounted on horizontal arms fixed to a vertical spindle. The wind catches the open faces of the cups and makes them rotate; the stronger the wind, the faster they spin. The rotating spindle is connected to a dial or counter which records the number of rotations. From the number of turns in a given time the wind speed is read off in kilometres per hour, metres per second or knots. The instrument is mounted on a mast in an open, exposed place, well clear of buildings and trees, so that the free flow of air is not obstructed. Readings are taken at regular intervals and entered in the weather register.