WAEC SSCE - Geography - 1990 (Essay)

Choosing (a) Iron and steel in the Ruhr and (b) Ship building in Japan.

(a) Six factors favouring iron and steel in the Ruhr region

1. Large local coalfields of good coking coal in the Ruhr valley, the main fuel and reducing agent for smelting.
2. Nearness to iron ore, formerly local and now imported cheaply from Sweden and France by water.
3. Excellent water transport on the Rhine and its tributaries and a dense canal/rail network for moving raw materials and finished steel.
4. Abundant water supply from the Rhine and Ruhr rivers for cooling and processing.
5. Large supply of skilled and general labour from the densely-populated region.
6. Huge home and European market for steel (machinery, vehicles, engineering) plus ample capital and long industrial tradition.

(b) Six factors favouring ship building in Japan

1. A long, deeply indented coastline with many sheltered natural harbours and deep water ideal for shipyards.
2. Cheap sea transport of imported raw materials (iron ore and coal) delivered directly to coastal yards.
3. A large, well-developed iron and steel industry nearby supplying steel plates.
4. Abundant, highly skilled and disciplined labour together with advanced technology and research.
5. Ample capital and strong government support for the industry.
6. A very large market: Japan's own huge merchant and fishing fleets plus a strong world export demand for ships.

(a) Outline map of Africa showing lumbering countries, saw-milling towns and timber ports

(DR Congo/Gabon with Libreville are also acceptable.)

(b) Three ways lumbering is important to West African countries

1. Foreign exchange: export of logs, sawn timber, plywood and veneer earns valuable foreign currency.
2. Employment and income: felling, haulage, saw-milling and furniture-making provide many jobs.
3. Raw materials and local needs: timber supplies building materials, furniture, poles, plywood and fuel, and supports paper and construction industries.

(c) Three problems resulting from the exploitation of timber

1. Deforestation and loss of forest cover, which destroys wildlife habitats and reduces biodiversity.
2. Soil erosion, leaching and loss of soil fertility once the protective forest is removed, and disturbance of the water cycle.
3. Over-exploitation and slow regeneration of valuable species, so the resource is being used up faster than it is replaced, threatening future supply.

(a) Similarities and differences between lines of latitude and longitude

Similarities

• Both are imaginary lines drawn on the globe used to locate places accurately.
• Both are measured in degrees, minutes and seconds from a fixed reference (the Equator for latitude, the Greenwich or Prime Meridian for longitude).

Differences

(b) Time calculation

The earth turns 15° of longitude in one hour, so 1° equals 4 minutes. Match start time in Banjul: 9.00a.m local time on 26th June, longitude 16°W.

(i) Bombay (74°E)

Bombay lies east of Banjul, so its time is ahead. Longitude difference = 16° + 74° = 90°.

\[ 90^{\circ} \times 4\,\text{min} = 360\,\text{min} = 6\ \text{hours} \]

Since Bombay is east, add 6 hours to 9.00a.m: 3.00p.m on 26th June.

(ii) Pittsburg (89°W)

Pittsburg lies west of Banjul, so its time is behind. Longitude difference = 89° - 16° = 73°.

\[ 73^{\circ} \times 4\,\text{min} = 292\,\text{min} = 4\ \text{hours}\ 52\ \text{minutes} \]

Since Pittsburg is west, subtract 4 hours 52 minutes from 9.00a.m: 4.08a.m on 26th June.

(a) Four reasons why countries exchange goods and services (with examples)

1. Uneven distribution of resources: a country sells what it has in surplus and buys what it lacks. Nigeria sells crude oil and buys machinery it does not produce.
2. Differences in climate and soils: countries import produce they cannot grow. Britain imports cocoa and coffee from the tropics; Nigeria imports temperate wheat.
3. Differences in technology and industrial development: less industrialised countries import manufactured goods from advanced ones. Nigeria imports vehicles and electronics from Japan, Germany and China.
4. Comparative cost advantage and specialisation: each country produces most cheaply what it is best suited for and trades for the rest, and services such as shipping, banking and tourism are also exchanged.

(b) Reasons for the low volume of trade between Nigeria and the rest of Africa

1. Similar (competing) economies: most African countries export the same primary products (cocoa, oil, minerals) and want to buy manufactures from outside, so they have little to sell one another.
2. Poor transport links between African countries: roads, railways and shipping lines were built to carry goods to Europe, not across Africa, so movement of goods within the continent is slow and costly.
3. Colonial trade ties and currency differences: long-standing links bind each country to former colonial and overseas partners, and different, non-convertible currencies plus trade barriers hamper intra-African trade.
4. Low levels of industrialisation and small purchasing power, together with language differences, political instability and smuggling, keep official trade among African states low.

Choosing (i) delta and (iii) caldera.

(a) Characteristics

Delta

• A roughly triangular or fan-shaped mass of alluvium built up where a river enters a sea or lake and drops its load.
• The main channel splits into many branching distributaries separated by low, flat, marshy islands and mud-flats.
• Composed of fine, fertile silt, sand and clay; very low-lying and liable to flooding (for example the Nile and Niger deltas).

Caldera

• A very large, roughly circular, basin-shaped hollow at the summit of a volcano, far wider than an ordinary crater (often several kilometres across).
• Bounded by steep inward-facing walls; the floor may hold a crater lake or later small cones (for example Ngorongoro).

(b) Mode of formation (with diagrams)

Delta: As a heavily-laden river reaches the still water of a sea or lake, its speed and carrying power suddenly fall. It deposits its sediment, coarsest first, building up beds of alluvium. Continued deposition blocks the mouth so the river divides into distributaries that push the land seaward. It forms best where the load is large, the current gentle and the tide/waves weak. A diagram shows the river dividing into distributaries across a triangular deposit.

Caldera: A caldera forms when a violent eruption empties the magma chamber beneath a volcano, or when the summit is blown off by an explosion. Losing this support, the unsupported top of the cone collapses inward (subsides) into the emptied chamber, leaving a huge circular depression far wider than the old vent. A diagram shows the cone before eruption, the emptied chamber, and the collapsed wide basin (caldera) afterwards.

As shown on the map above:

(b) Production of rubber

Rubber is obtained from the latex, or milky sap, of the rubber tree. Rubber trees are first planted in nurseries and later transferred to plantations at regular spacing. The trees are weeded, protected from pests and diseases, and allowed to grow for about six to eight years before tapping begins.

Tapping is usually done early in the morning, when the latex flows freely. The worker makes a shallow slanting cut in the bark of the tree with a sharp tapping knife. A small spout directs the latex into a cup fixed below the cut. The latex is allowed to drip into the cup and is later collected in buckets or pails.

The collected latex is taken to a processing shed, where chemicals such as formic acid are added to make it coagulate. The coagulated rubber is pressed or rolled into sheets to remove water. The sheets are then dried, often by smoking, graded and packed for sale to processing factories or export agents.

(c) Factors hindering large-scale rubber production in West Africa

• Long period of maturity: Rubber trees take about six to eight years before they can be tapped. Farmers therefore wait for a long time before earning income from the plantation.
• High capital requirement: Establishing a rubber plantation requires money for land clearing, seedlings, labour, fertilizers, tapping equipment, processing sheds and transport. Many farmers cannot obtain enough capital or credit.
• Pests and diseases: Diseases such as leaf blight and attacks by insects can reduce the number of healthy trees and lower latex yield. Control measures may be costly and unavailable to small-scale farmers.

Other related difficulties include poor rural roads, inadequate processing facilities, shortage of skilled tappers, fluctuating world prices for rubber and competition from synthetic rubber.

Petroleum Mining in North Africa

The sketch map below shows the major petroleum-producing areas of North Africa, the main pipelines and the coastal export terminals referred to in this answer.

(a) Major areas

The chief producing countries are Libya, Algeria, Egypt and, in smaller quantities, Tunisia.

• Libya: the main fields lie in the Sirte (Sirtica) Basin - Zelten (Nasser), Sarir, Amal and Waha.
• Algeria: the great inland Saharan fields of Hassi Messaoud (oil) and Hassi R'Mel (oil and natural gas).
• Egypt: production comes from the Gulf of Suez, the Sinai Peninsula and the Western Desert.
• Tunisia: smaller fields such as El Borma in the south.

(b) Methods of mining

Petroleum is obtained by drilling, in the following stages:

1. The oil-bearing (reservoir) rocks are first located by geological and geophysical survey, chiefly seismic prospecting, and the underground rocks are sampled and tested for traces of oil.
2. When a promising oil trap is found, a well is sunk to reach it by means of a drilling rig (derrick). Drilling may be on land in the desert or offshore on the continental shelf (as in the Gulf of Suez).
3. Where there is enough natural underground (gas) pressure, the crude oil flows up the well on its own; where the pressure is low it is brought up by pumping.
4. A system of valves fitted at the well-head, called a "Christmas tree", is used to control the flow of crude oil into storage tanks.
5. At the surface the crude oil is separated from gas and water and stored in tanks before being sent for refining or export.

(c) Transportation

Crude oil is moved from the desert fields to the coast mainly through pipelines - for example to the Libyan terminals at Marsa el Brega and Es Sider, and to the Algerian terminals at Skikda and Arzew. From these coastal terminals the oil is loaded into oil tankers (ships) and exported across the Mediterranean Sea to Europe and beyond. Natural gas is likewise piped to the coast and shipped as liquefied natural gas (LNG).

(d) Importance to the economy

1. It is the chief source of foreign-exchange earnings and government revenue.
2. When refined it yields petrol, kerosene, diesel and gas for domestic use and industry.
3. Its by-products are used in making insecticides, petroleum jelly, lubricating oil and other chemicals, so it has led to the growth of refineries and petro-chemical industries.
4. It provides raw materials for many associated industries and has encouraged urban, road and port development.
5. It provides gainful employment for many people, directly and indirectly.

As shown in the diagram above, urban settlements may grow from a single large built-up area into joined towns and, eventually, into a very extensive chain of cities.

(a) Distinguishing characteristics of three types of urban settlements

1. City
A city is a large, densely populated urban settlement with many buildings, roads and specialised services. It is usually larger and more important than a town. A city has a concentration of administrative offices, industries, markets, banks, schools, hospitals, transport terminals and recreational facilities. It serves not only its residents but also people in the surrounding rural areas. In the diagram, it is represented as one main continuous built-up urban area.

2. Conurbation
A conurbation is formed when two or more neighbouring towns or cities expand outward until their built-up areas meet and merge. Although they become physically joined into one continuous urban area, the original settlements may still retain their separate names, local governments and identities. The diagram illustrates this by showing adjoining urban centres whose growth has removed the open space between them.

3. Megalopolis
A megalopolis is a very large urban region formed when several cities and conurbations grow and link together along major transport routes. It covers a wide area and contains a very large population, numerous industries, commercial centres and communication networks. Unlike a conurbation, which normally involves a few adjoining towns, a megalopolis consists of many large urban centres forming an extensive urban belt, as indicated in the diagram.

(b) Four problems of urbanization

1. Housing shortage and slum development: Rapid population increase often exceeds the supply of decent houses. Many low-income migrants therefore live in overcrowded houses, informal settlements and slums with poor sanitation and unsafe buildings.
2. Unemployment and underemployment: Cities attract many people seeking paid work, but jobs may not be sufficient for all. This leads to unemployment, low-paid casual work, street hawking and, in some cases, increased crime and social unrest.
3. Pressure on social amenities: Schools, hospitals, water supply, electricity, drainage, waste-disposal facilities and recreation centres become overstretched. The result may be poor health care, inadequate classrooms, irregular water supply and poor refuse collection.
4. Traffic congestion and transport problems: The large number of people, vehicles and commercial activities causes congestion on urban roads. This results in long travelling times, accidents, noise, air pollution and higher transport costs.

Similarities and differences between road and railway transport

Similarities

• Both are land-based means of transport that move passengers and goods over fixed routes on the earth's surface.
• Both require heavy capital to build and constant maintenance of the track/route.
• Both are affected by relief; steep slopes, rivers and swamps raise construction costs (bridges, cuttings, embankments) for each.
• Both link production areas with markets and ports and so aid trade and development.

Differences

(a) Location on the outline map of Nigeria

(i) One important sea port and one important river port:

• Sea port: Apapa Port, Lagos – located on the south-western coast of Nigeria.
• River port: Onitsha River Port – located on the eastern bank of River Niger in Anambra State.

(ii) Road or railway serving each port:

• Apapa Port is served by the Lagos–Ibadan–Kano railway and major roads such as the Lagos–Ibadan Expressway.
• Onitsha River Port is served by the Onitsha–Enugu–Port Harcourt trunk road.

(iii) One international airport and one domestic airport:

• International airport: Murtala Muhammed International Airport, Ikeja, Lagos.
• Domestic airport: Ilorin Airport, Ilorin, Kwara State.

(b) Four factors which have helped in the development of Apapa (Lagos) Port:

1. Apapa Port handles a large proportion of Nigeria’s imports and exports.
2. It is located on a good natural harbour with sheltered waters.
3. It is served by good roads, railway lines and sea routes linking it with the hinterland and foreign countries.
4. It has a large and highly populated hinterland with many industries and commercial activities.

(a) As shown in the sketch map above, three major vegetation belts in Nigeria are:

• Mangrove swamp forest, found along the coastal and Niger Delta areas.
• Tropical rainforest, found mainly in southern Nigeria, north of the mangrove swamp belt.
• Guinea savanna, found in the central belt of Nigeria.

(b) Effects of climate on the tropical rainforest vegetation belt

• The belt receives heavy rainfall, usually above \(1,500\text{ mm}\) annually. This provides sufficient moisture for plant growth throughout the year.
• Rainfall is fairly regular and the dry season is short. Consequently, most trees do not shed all their leaves at the same time, making the forest evergreen.
• High temperatures throughout the year encourage rapid growth of trees, shrubs, climbers and other plants.
• High relative humidity and abundant sunshine promote luxuriant and dense vegetation growth.
• The favourable hot and wet conditions produce tall hardwood trees with broad leaves, thick undergrowth and several layers of vegetation.

(c) Resources found in the tropical rainforest belt and their uses

Choosing (b) Irrigation farming in the Nile Valley, (c) Pastoral nomadism in West Africa and (a) Plantation agriculture in East Africa.

(b) Irrigation farming in the Nile Valley

• Practised in a hot desert with almost no rain, so all water comes from the River Nile led onto the land through basins, canals and lifting devices (shaduf, sakia, pumps).
• Intensive and sedentary, on narrow but very fertile alluvial flood-plain land, using much hand labour.
• Grows cash and food crops such as cotton, rice, sugar cane, wheat and vegetables, often two or more crops a year.

(c) Pastoral nomadism in West Africa

• Practised in the dry savanna and Sahel (for example by the Fulani) where rainfall is low and unreliable and crop farming is difficult.
• The herders move about (are migratory) with their cattle, sheep and goats in search of pasture and water, following the rains north and south.
• It is extensive and subsistence in nature; animals supply milk, meat and hides, and wealth is measured in the size of the herd rather than in crops.

(a) Plantation agriculture in East Africa

• Large estates, often foreign or company owned, growing a single cash crop (monoculture) such as tea, coffee, sisal or sugar for export.
• Uses much hired labour, heavy capital, scientific methods and on-site processing of the crop.
• Located where climate, soils and relief suit the crop (for example tea and coffee on the cooler, wetter highlands), with good transport to ports.

(a) Outline map of Nigeria showing crop-producing areas and vegetation belts

The sketch map below shows the required crop areas and the two named vegetation belts.

• (i) Crop areas
  • Oil palm: the south-east / Niger Delta (Imo, Rivers, Akwa Ibom).
  • Cotton: the far north (Katsina, Zaria/Kaduna, Gombe).
  • Cocoa: the south-west (Ondo, Ogun, Oyo, Ekiti).
• (ii) Vegetation belts
  • Forest belt: the southern tropical rainforest belt along the coast.
  • Savanna belt: the Guinea/Sudan savanna belt of the middle and north.

(b) Four ways in which cocoa is important to the economy of Nigeria

1. Foreign-exchange earner: cocoa is a leading agricultural export and brings in foreign currency that strengthens the nation's reserves.
2. Raw material for industries: cocoa beans supply local factories that make beverages such as Bournvita, as well as cocoa butter and confectionery, so value is added at home.
3. Source of employment: cocoa growing, harvesting, processing, transporting and marketing provide jobs for a large number of people, especially in the south-west.
4. Source of income and government revenue: it gives farmers cash income while taxes and marketing-board proceeds provide revenue that funds roads, schools and other amenities in the producing areas.

(c) Three problems facing the cultivation of cocoa

1. Pests and diseases such as capsids and black-pod disease, which attack the trees and reduce yields.
2. Poor processing of the beans, leading to low-grade produce that fetches lower prices on the market.
3. Poor, low-yielding cocoa species and ageing trees, together with limited use of improved seedlings, fertiliser and capital, which keep output low.

A geographical account of fishing in Southern Africa

Southern Africa is one of the richest fishing regions in the world because the cold Benguela Current flows northward along its western (Atlantic) coast. This current causes upwelling of cold, nutrient-rich water from the sea bed, which supports enormous quantities of plankton and therefore vast shoals of fish. The map below shows the main fishing grounds and ports.

(a) Important fishing areas and fishing ports

Fishing is carried out in two main settings:

• Offshore (marine) fishing is by far the most important. The richest grounds lie off the cool Atlantic (Benguela Current) coast of Namibia and the western Cape of South Africa, where upwelling supports huge shoals. Fishing also extends along the southern and eastern (Indian Ocean) coasts and into the deep seas of both the Atlantic and Indian Oceans.
• Inland fishing is minor and much less important. It is carried out on rivers such as the Orange River and the Great Fish River, and on inland lakes and dams by local fishermen.

The chief fishing ports are Walvis Bay (Namibia), and Saldanha Bay, Cape Town, Port Elizabeth, East London and Durban in South Africa.

(b) Methods of fishing

• Trawling: large motorised trawlers drag bag-shaped nets along or near the sea bed to catch demersal (bottom-living) fish such as hake. This is the main large-scale method used in the deep oceans.
• Purse-seining and drift/gill netting: nets are used to surround and trap surface-swimming (pelagic) shoal fish such as pilchard and anchovy.
• Line fishing: hooks and lines are used for larger fish such as tuna and snoek.
• Traps and small nets: used by local fishermen inland on rivers, lakes and estuaries on a small scale.

(c) Major types of fish caught

The main catch consists of:

• Pelagic (surface) species - pilchard (sardine), anchovy, herring and mackerel (horse mackerel).
• Demersal (bottom) species - hake (stockfish).
• Other valuable species - tuna, snoek and rock-lobster (crayfish).

(d) Preparation and marketing of fish

Once landed, the fish are cleaned and chilled or frozen on board the vessels and in cold stores on shore. The catch is then either sold fresh, or processed by canning (for example sardines), salting, drying and smoking. Much of the pelagic catch is turned into fish meal and fish oil for animal feed and fertiliser. The products are sold fresh in local markets, distributed inland, and large quantities of frozen, canned and processed fish are exported to Europe and other overseas markets.

(e) Importance to the economy

• It provides a rich and cheap source of protein food for the people.
• The export of frozen fish, canned fish, fish meal and lobster earns valuable foreign exchange for the countries.
• It provides employment for many people in fishing, canning, processing, transport and boat building.
• It has led to the establishment of fish-processing and canning industries and supplies raw material (fish meal) for animal feed and fertiliser, supporting related industries.

(a)(i) Annual range of temperature

Range = highest − lowest = \(21^{\circ}\text{C} - 13^{\circ}\text{C} = 8^{\circ}\text{C}\).

(a)(ii) Annual rainfall

Add the twelve monthly figures: \(18+15+23+48+97+114+94+86+58+41+28+20 = 642\ \text{mm}\).

(b) Distribution of rainfall

Rain falls in every month, so there is no completely dry month. There is a single maximum in June (114 mm) and a single minimum in February (15 mm). The wettest period runs from May to September (the middle of the year), while the driest months are at the start of the year (January to March). The regime therefore shows one marked rainy season with a moderate total of 642 mm.

(c) Type of climate

The temperature range is very small (8°C) and temperatures stay mild to warm all year (13 to 21°C), with the warmest months at the beginning of the year and the coolest in the middle. The rainfall maximum comes in the cool middle-of-year months, meaning the wet season is the cool season and the warm season is comparatively dry. This gives a Mediterranean (Warm Temperate Western Margin) climate in the Southern Hemisphere: mild, wet cool-season and warm, drier high-sun season.

(d)(i) Natural vegetation

Mediterranean woodland and scrub (evergreen sclerophyllous woodland, such as maquis or chaparral).

(d)(ii) Main characteristics of the vegetation

• Trees and shrubs are evergreen and drought-resistant (xerophytic) to survive the dry warm season.
• Leaves are small, thick, leathery or waxy to cut down water loss, and many plants have thick or corky bark (e.g. cork oak, olive).
• Plants develop long deep root systems to reach underground water.
• Vegetation is generally open and low, forming a mixture of short trees, aromatic shrubs and bushes rather than dense forest.

(a) Three types of mountains with an example of each

1. Fold mountains – the Atlas, Alps or Himalayas.
2. Block (fault) mountains / horst – the Ruwenzori (or the Vosges).
3. Volcanic mountains – Mount Cameroon (or Kilimanjaro).

(Residual mountains, such as inselbergs on the Jos Plateau, are also acceptable.)

(b) Process of formation of fold mountains

Fold mountains are formed by compression (lateral squeezing) of the earth's crust. Over long periods, thick layers of sediment collect in a large downwarp of the crust called a geosyncline, usually beneath a sea. When two crustal plates move towards each other, the intervening sediments are squeezed from both sides. Because they cannot escape, the rocks are buckled and folded into a series of upfolds (anticlines) and downfolds (synclines). Continued pressure raises these folds high above sea level to form fold mountains; where pressure is very great the folds may become overfolded or overthrust. The Himalayas, formed by the collision of the Indian and Asian plates, are a good example.

(c) Four ways mountains are of great importance to man

1. They act as sources of rivers (water towers), feeding streams used for water supply, irrigation and hydro-electric power.
2. They influence climate and rainfall, causing relief rainfall on their windward slopes and creating cooler, healthier highland areas.
3. They are storehouses of minerals, forests and good grazing/farming land on their slopes and provide sites for tourism and mountaineering.
4. They serve as natural boundaries and defensive barriers between peoples and countries.

As shown on the sketch map above, Lagos and its surrounding south-western urban belt represent an area of high population density, while the Middle Belt area around Makurdi represents an area of low population density. The towns marked are Lagos in the densely populated area and Makurdi in the sparsely populated area.

(b) Reasons for the high population density in Lagos

1. Commercial activities: Lagos is Nigeria's leading commercial centre, with large markets, banks, offices and business organisations that attract people.
2. Industries: Many manufacturing and processing industries are located in and around Lagos, providing jobs for workers.
3. Employment opportunities: Government offices, transport services, ports, trade, tourism and private companies offer a wide range of employment opportunities.
4. Port and transport facilities: Lagos has major seaports, an international airport, rail and road links. These encourage trade, migration and settlement.
5. Former federal capital: Lagos was formerly the Federal Capital of Nigeria, so many administrative offices, institutions and services developed there.
6. Social amenities: The area has many schools, hospitals, electricity, water supply, communication facilities and recreational services.

Reasons for the low population density in the Makurdi or Middle Belt area shown

1. Limited industrial development: Compared with Lagos, there are fewer large industries and commercial establishments to provide employment and attract migrants.
2. Predominantly agricultural occupation: Much of the surrounding area is rural and people are mainly engaged in farming, which does not concentrate population as strongly as urban industrial activities.
3. Inadequate social amenities: Some rural parts of the area have fewer good roads, hospitals, schools, pipe-borne water and other services than major urban centres.
4. Health hazards: In some riverine and bush areas, tsetse flies and black flies have historically discouraged settlement because they spread diseases such as sleeping sickness and river blindness.
5. Accessibility problems: Seasonal flooding of rivers and poor road conditions in some places may make movement and settlement difficult.
6. Historical insecurity: Past slave raids and communal conflicts in parts of the Middle Belt discouraged permanent settlement in some areas.

Any four relevant reasons for each area are sufficient.

(a) Three reasons to show that the earth is spherical

1. Circumnavigation: ships and aircraft travelling steadily in one direction eventually return to their starting point without reversing, which is only possible on a rounded body.
2. Ship and horizon evidence: as a ship approaches, the top of its mast is seen first and the hull last (and the reverse as it leaves); the horizon always appears circular from any high point.
3. Earth's circular shadow and space photographs: during a lunar eclipse the earth casts a circular shadow on the moon, and photographs taken from space show the earth as a sphere. The disappearance of the lower part of distant objects and the changing altitude of the Pole Star with latitude also confirm it.

(b) Three effects of the revolution of the earth

1. The changing seasons (spring, summer, autumn, winter) result as the earth revolves round the sun with its tilted axis.
2. Varying length of day and night at different times of the year, especially away from the equator.
3. Changing altitude and apparent migration of the noon sun between the Tropics, and the occurrence of the equinoxes and solstices; it also fixes the length of the year (about 365¼ days), giving leap years.

(c) Noon altitude of the sun at the Tropic of Capricorn on June 21

On 21 June (the June solstice) the overhead (vertical) sun is at the Tropic of Cancer, 23½°N. The Tropic of Capricorn is 23½°S.

The angular distance between the place and the point of the overhead sun is:

23½° + 23½° = 47°.

Noon altitude of the sun = 90° minus this angular distance:

\[ 90^{\circ} - 47^{\circ} = 43^{\circ} \]

The noon altitude of the sun at the Tropic of Capricorn on 21 June is 43°.

Factors responsible for very high population density

(a) North-East of the USA (the Manufacturing/Boston-Washington belt)

1. Early settlement and industrialisation: this was the first area settled by Europeans and the cradle of American manufacturing, so towns and industries grew early.
2. Rich resources and power: nearby coalfields (Appalachians), iron ore from the Great Lakes and abundant capital fed heavy industry, attracting workers.
3. Excellent transport and trade: fine natural harbours (New York, Boston), navigable rivers, the Great Lakes-St Lawrence route and dense rail/road networks made it a great commercial and port region.
4. Concentration of commerce, finance and services in great cities such as New York, together with continuing in-migration, keeps densities high; the cool temperate climate is also favourable to work.

(b) The Indus and Ganges deltas/plains

1. Fertile alluvial soils deposited by the rivers, giving high crop yields that can feed a dense population.
2. Ample water for irrigation from the rivers plus the monsoon rains, allowing intensive, often double-cropped, farming of rice, wheat and jute.
3. Flat, easily-cultivated and easily-settled lowland that supports intensive wet-rice agriculture, which itself demands much labour.
4. Long history of settlement and agrarian civilisation, with many old towns and cities and a favourable warm climate, so numbers have built up over centuries.

(a)(i) Two distinct types of soil erosion

1. Sheet erosion (thin, even removal of topsoil by surface run-off over a wide area).
2. Gully erosion (deep channels and ravines cut by concentrated running water). Rill and wind erosion are also acceptable types.

(ii) Where each type is most common

• Sheet/wind erosion – the semi-arid far north of Nigeria (Sokoto, Katsina, the Sahel margin) with sparse cover and dry, loose soils.
• Gully erosion – the south-east, especially the Agulu-Nanka and Udi areas of the Anambra/Enugu region.

(b) Three factors responsible for gully erosion

1. Heavy, intense rainfall with strong surface run-off that scours and deepens channels.
2. Steep, sloping land that increases the speed and cutting power of running water.
3. Removal of protective vegetation (through farming, bush burning, over-grazing and building) on loose, easily-eroded sandy soils, so the bare surface is quickly cut into gullies.

(c) Three measures being taken to solve soil erosion in the area

1. Afforestation and re-vegetation: planting trees, grasses and cover crops to bind the soil and break the force of rain and run-off.
2. Construction of check dams, drains and terraces / contour ploughing to slow run-off, trap sediment and lead water away safely.
3. Filling and stabilising existing gullies with sandbags, stones and gabions, controlling farming on steep slopes, and public enlightenment against bush burning and overgrazing.

(a) Identification on the sketch map

As shown on the map above, the following features should be correctly located and labelled:

• Western Uplands: located in south-western Nigeria, mainly around the Yoruba highlands of Oyo, Ogun, Osun, Ondo and Ekiti areas.
• Udi Hills: located in south-eastern Nigeria, west of Enugu, around the Udi-Enugu area.
• North Central Plateau: located in central Nigeria, around Jos in Plateau State.
• River basin: the Niger-Benue River Basin, covering much of central Nigeria where River Niger and River Benue meet at Lokoja.
• Natural lake: Lake Chad, in the north-east, on Nigeria's border with Chad, Niger and Cameroon.
• Man-made lake: Kainji Lake, in north-western Nigeria on River Niger. It was formed by the construction of Kainji Dam.

(b) Importance of river basins in the development of Nigeria

• Agriculture: River basins have fertile alluvial soils which support crop cultivation. For example, the flood plains of the Niger-Benue Basin support the cultivation of rice, maize, vegetables and sugar cane, while the Chad Basin supports wheat, rice, tomatoes and vegetables.
• Irrigation: Water from rivers and reservoirs is used to irrigate farmland, especially in the dry northern region. Examples include the Kano River irrigation scheme, Bakolori irrigation project and irrigation around the Hadejia-Jama'are and Chad basins.
• Hydroelectric power generation: Rivers provide water for generating electricity. Kainji, Jebba and Shiroro dams on the Niger River system produce hydroelectric power for homes, industries and commercial activities.
• Fishing: Rivers, lakes and flood plains provide fish and employment for fishing communities. Fishing is important around Lake Chad, Kainji Lake, River Niger and the Niger Delta creeks.
• Water supply: River basins supply water for domestic use, industries and livestock. Major towns obtain treated water from rivers, dams and reservoirs within their drainage basins.
• Transportation and trade: Parts of River Niger and River Benue are navigable during high-water periods. They facilitate the movement of people and goods, particularly between Lokoja, Onitsha, Warri and other riverine settlements.
• Settlement and industry: River valleys provide relatively flat land, water and fertile soils, encouraging settlement and industrial activities. Important towns such as Lokoja, Onitsha, Makurdi and Yola developed along major river basins.
• Tourism and recreation: Lakes and dams such as Kainji Lake attract tourists and support recreational activities such as boating, fishing and wildlife conservation in the Kainji Lake National Park area.

(c) Factors limiting the use of river basins in Nigeria

1. Seasonal flow of rivers: Many rivers have reduced water volume in the dry season, making irrigation, navigation, fishing and water supply difficult at certain times of the year.
2. Swampiness and flooding: Flood plains and deltaic areas are often waterlogged or flooded. This makes road construction, farming, settlement and other development projects difficult and costly.
3. Poor accessibility: Many river-basin areas, especially swampy and remote parts of the Niger Delta and Chad Basin, have inadequate roads and transport facilities. This limits the movement of people, farm produce and equipment.