WAEC SSCE - Geography - 2003

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Maelezo ya Majibu

Abrasion, attrition, and deflation are processes of wind erosion. Abrasion is the process by which wind carries small rock particles that strike and scrape against rocks, breaking them apart. Attrition is the process by which these small rock particles collide with each other, breaking into even smaller particles. Deflation is the process by which wind removes and carries away loose particles, such as sand or dust, leaving behind a surface that is more compact and solid. Together, these processes can erode and shape landscapes in arid regions with little vegetation cover, such as deserts.

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Among the four options given, Libya is the leading producer of petroleum. Libya is a country located in North Africa, with significant reserves of crude oil, making it one of the top oil producers in Africa and the world. Oil and gas production is the backbone of Libya's economy, accounting for over 90% of export earnings and more than 60% of its GDP. In recent years, Libya has consistently ranked among the top 20 oil-producing countries in the world, with an estimated 48 billion barrels of proven reserves. Therefore, Libya is the correct answer to the question.

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Chalk is a good example of an organically formed sedimentary rock. It is made up of the microscopic skeletons of marine plankton that lived millions of years ago. These skeletons settled on the ocean floor and over time, were compacted and cemented together to form the soft, white rock that we know as chalk. The process of formation of chalk is an example of biological sedimentation. Chalk is often found in areas that were once covered by shallow seas, such as the White Cliffs of Dover in England.

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The low level of trade among African countries is primarily due to the similarity of products they produce. Many African countries are reliant on the production of primary commodities, such as raw materials and agricultural products, and have a limited industrial base. This means that they often produce similar products, which reduces the need for them to trade with each other. Additionally, poor infrastructure, including transportation systems and communication networks, and trade barriers such as tariffs, import quotas, and bureaucratic red tape, also hinder trade among African countries. The high demand for home-made products and liberalization of trade are not major factors contributing to the low level of trade among African countries.

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The ultimate source of energy in the biosphere is the sun. The sun emits electromagnetic radiation, including visible light, which is used by plants in the process of photosynthesis to produce organic compounds that store energy. These organic compounds are consumed by other organisms, transferring energy through the food chain. Therefore, without the sun, there would be no energy available for life to exist on Earth.

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Coal is the type of rock that is a source of energy. Coal is a sedimentary rock that is formed from the accumulation of plant material over millions of years. When coal is burned, it releases energy in the form of heat and is used as a fuel for various purposes such as electricity generation, heating, and cooking. Coal is one of the most widely used sources of energy in the world and plays an important role in many economies.

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Fold mountains are formed as a result of compressional forces. When two tectonic plates collide, the rock layers between them are pushed together and forced upward, causing the crust to fold and buckle. This process is known as orogeny and it results in the formation of fold mountains, such as the Himalayas, the Alps, and the Andes. The compressional forces can also cause the rocks to fracture and fault, leading to the formation of thrust faults and overthrusts. Over millions of years, erosion can wear down the mountains, but the forces that created them can still be seen in their folded and faulted rock layers.

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Soil is important to man in many ways. It serves as a medium for plant seeds to germinate, provides support for growing plants, brings water to the roots, and supplies minerals to the plants. Therefore, the correct answer is option D: I, II, III, and IV.

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Heavy manufacturing industries are characterized by their dependence on electricity-powered equipment. These industries typically produce goods such as machinery, vehicles, and heavy equipment in large quantities. Due to the size and complexity of the machinery required, heavy manufacturing industries typically require a large amount of space for their workshops and factories. Additionally, heavy manufacturing industries often employ a significant number of workers, many of whom are specialized and highly skilled in their trade. Overall, heavy manufacturing industries tend to be capital-intensive and require significant investment in machinery and equipment.

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The thin layer of unconsolidated mineral particles and organic matter that covers the land surface is called soil. Soil is a complex mixture of minerals, organic matter, water, and air, and it is a vital component of the Earth's ecosystems. Soil provides a medium for plant growth, supports the food chain by providing nutrients for organisms, filters water, and stores carbon. It is formed through the weathering of rocks and other geological processes, and it varies widely in composition, texture, and fertility depending on factors such as climate, vegetation, and topography.

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The country that is not a member of the Economic Community of West African States (ECOWAS) is Cameroun. ECOWAS is a regional organization of West African countries that was established to promote economic integration among its member states. It was founded in 1975 and currently has 15 member states, including Mali, Niger, and Burkina Faso. However, Cameroon is not a West African country, and therefore, it is not a member of ECOWAS.

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Pastoral nomadism is a type of subsistence agriculture that involves raising livestock, such as cattle, sheep, and goats, by constantly moving from one place to another in search of food and water for their animals. This practice is common in arid and semi-arid regions of the world, where there is limited rainfall and vegetation. In West Africa's savanna areas, pastoral nomadism is predominantly practiced by the Fulani people, who are known for their long-distance cattle herding and transhumance practices, where they move their animals seasonally in search of greener pastures.

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The feature formed from the solidification of highly fluid basic lava on the earth's surface is known as a "basalt plateau." A basalt plateau is a large area of flat, elevated land that is formed by the accumulation of layers of basaltic lava flows. These lava flows are usually highly fluid and can cover vast areas of land. As they cool and solidify, they form a thick layer of basalt rock that can be several hundred meters thick. Over time, erosion can remove the overlying rock and expose the basalt plateau. Basalt plateaus are common in volcanic regions and are found all over the world.

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Maelezo ya Majibu

An aquifer is a water-bearing rock layer that can store and transmit groundwater. It is usually found between two layers of impermeable rock that prevent the water from seeping out. The permeable rock can be sandstone, limestone, or other types of rock that allow water to flow through their pores and spaces. Aquifers are important sources of water for wells and springs, and they can be replenished by precipitation and surface water that percolates down into the ground.

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Loamy soils are better for agriculture than other soil types because they retain air, moisture, and humus, which is important for plant growth. The soil texture of loamy soils is such that it allows for a balance of water retention and drainage, making it ideal for plants to absorb water and nutrients while preventing waterlogging. Additionally, loamy soils are rich in mineral nutrients and organic matter, such as humus, which supports the growth of crops. The organic matter in loamy soils provides a source of nutrients for plants and improves the structure of the soil, making it easier for roots to penetrate and access water and nutrients. Therefore, loamy soils are considered the most fertile and productive soil type for agriculture.

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The warm ocean current is the Mozambique current. It flows southwards along the southeastern coast of Africa, originating from the equatorial counter-current in the Indian Ocean. This current brings warm water from the tropics towards the poles, influencing the climate and weather patterns of the areas it passes through. The other options listed are all cold ocean currents, which flow from polar regions towards the equator, carrying cold water with them.

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Flooding can be prevented by planning towns and cities in such a way that they take into account the possibility of flooding. This can involve building structures on higher ground, creating designated flood plains, and ensuring that drainage systems are properly designed and maintained. Dumping refuse in drainage channels can actually exacerbate flooding by clogging up the system, while building houses and roads in flood plains can put people and property at risk. Building strong fences around buildings does not directly prevent flooding, although it may provide some protection from the effects of flooding such as debris carried by the flood waters.

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Sheet erosion tends to be more serious than other forms of erosion because it involves more widespread removal of soil from the land surface. Unlike other forms of erosion that remove soil from specific points, sheet erosion removes the topsoil and exposes the subsoil. The subsoil is not suitable for crop production, and the removal of the topsoil leads to soil infertility, which affects agricultural productivity. Additionally, sheet erosion is more difficult to control because it is caused by surface runoff, which is difficult to redirect or control, especially on sloping land.

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An inselberg is a residual hill with steep sides and usually exposed by denudation. It is a geological landform that stands out conspicuously above the surrounding plain due to its resistance to erosion. Inselbergs are typically composed of hard rocks such as granite, and they are often found in arid or semi-arid regions where weathering is minimal. Therefore, the correct option is: "a residual hill with steep sides and usually exposed by denudation."

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The feature found in the upper course of a river is a gorge. This is a narrow and steep-sided valley that is usually formed as a result of erosion by fast-flowing water over a long period of time. The river in the upper course has a high gradient, and the water flows with greater force and velocity, thus eroding the rock and soil more efficiently. The rocks in the upper course of a river are typically harder, and the river may have to cut through them, forming a narrow and steep-sided valley known as a gorge. Gorges are often characterized by vertical cliffs or near-vertical cliffs, and they may have rapids and waterfalls where the river's gradient is steeper.

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The statement that is not true of Cool Temperature Western Margin Climate is "summer rainfall and water drought". This is because this type of climate has a high and relatively evenly distributed rainfall throughout the year, with no distinct dry season. The other options are true. The mean annual temperature is between 5°C and 16°C, with an annual temperature range of 13°C. The summers are moderately warm and the winters are fairly mild.

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Stalagmites are features of limestone regions. Limestone is a sedimentary rock formed from the accumulation of organic and inorganic materials, such as the remains of marine organisms and minerals, over time. It is composed primarily of calcium carbonate. Limestone regions are characterized by karst topography, which is characterized by sinkholes, caverns, and underground drainage systems. Stalagmites are formed in caves as a result of water dripping from the cave ceiling, depositing calcium carbonate on the cave floor over time. The resulting cone-shaped deposit grows upwards from the cave floor, forming a stalagmite.

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The mode of transport that is best suited for the distribution of petroleum products is pipeline. Pipelines are specifically designed for the transportation of liquids and gases over long distances, making it an efficient means of transporting petroleum products. It is cost-effective, safe, and minimizes the risk of accidents and environmental pollution. Additionally, pipelines require minimal maintenance, have a high capacity for transport, and reduce the cost of transportation compared to other modes of transport like road, water, or rail. Therefore, pipelines are the most preferred mode of transport for the distribution of petroleum products.

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Maelezo ya Majibu

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The process of weathering in limestone region is mainly solution. Limestone is a sedimentary rock made up of calcium carbonate, which is easily dissolved in water that is slightly acidic. Over time, rainwater containing carbon dioxide dissolves the calcium carbonate, creating cracks and holes in the limestone. This process is known as solution and is the main process of weathering in limestone regions. As the limestone dissolves, it forms features such as sinkholes, caves, and underground drainage systems.

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The combination of sial and sima constitute the lithosphere. Sial is the upper layer of the Earth's crust, which is composed of lighter rocks such as granite, while sima is the lower layer composed of heavier rocks such as basalt. The lithosphere is the solid, outermost layer of the Earth, which includes both the crust and the uppermost part of the mantle. It is the rigid layer upon which the Earth's tectonic plates move and interact with each other, causing earthquakes, volcanic eruptions, and the formation of mountains.

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(a) Explanation of salinity

Salinity is the degree of saltiness of sea or ocean water, that is, the total amount of dissolved mineral salts (chiefly sodium chloride) present in a given quantity of water. It is usually expressed in grams of salt per 1000 grams of water (parts per thousand, \(\text{ppt or } ‰\)). The average salinity of the oceans is about \(35‰\) (35 grams per 1000 grams of water).

(b) Three factors causing variations in salinity

• Rate of evaporation: Where evaporation is high (hot, dry tropical and enclosed seas), water is removed but salt is left behind, so salinity is high (e.g. the Red Sea and the Dead Sea). Where evaporation is low, salinity is lower.
• Amount of fresh water added: Heavy rainfall, the inflow of large rivers, and the melting of ice add fresh water and dilute the salt, lowering salinity. Areas near river mouths and the equator therefore have lower salinity.
• Movement and mixing of water: Ocean currents and the free movement of water in the open sea mix and even out salinity, while enclosed and land-locked seas with little exchange develop extreme (high or low) salinity.

(c) Three ways oceans are important to man

• They are a major source of food (fish, shellfish and other sea foods) and of minerals such as common salt.
• They serve as cheap highways for transport and trade by ships between countries and continents.
• They influence climate (moderating temperatures and providing moisture for rainfall) and are a source of energy, petroleum and tourism.

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(a) Five characteristics of manufacturing industries in Tropical Africa

• They are mostly light, consumer-goods and processing industries (food, drinks, textiles, soap) rather than heavy industries.
• Many are agro-based / raw-material based, processing local farm and mineral products for local use or export.
• They are few, small-scale and unevenly distributed, concentrated in a few large towns and ports (e.g. Lagos, Nairobi).
• They rely heavily on imported machinery, spare parts, capital and technical expertise from developed countries.
• They employ relatively low levels of technology and are largely foreign-owned or dependent on foreign investment, producing mainly for the home market.

(b) Five problems facing manufacturing industries in Tropical Africa

• Shortage of capital for establishing and expanding industries.
• Inadequate infrastructure - unreliable electricity, poor roads and water supply raise costs and disrupt production.
• Shortage of skilled manpower and technology, forcing dependence on expensive foreign experts and imported equipment.
• Small home market and low purchasing power of the largely poor population, limiting sales.
• Competition from cheap imported goods, together with shortage of quality raw materials and political instability, which discourage investment.

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(a)(i) Explanation of settlement

A settlement is any place where people live, ranging from a single dwelling to a large city, together with the buildings and structures they use for shelter and other activities. It is a place where human beings have established their homes and carry on their daily life.

(a)(ii) Two major types of settlement

• Rural settlement (villages and hamlets, mainly agricultural).
• Urban settlement (towns and cities, mainly non-agricultural).

(By pattern they may also be grouped as nucleated/compact or dispersed/scattered.)

(b) Four factors that influence the location of settlements

• Water supply: people settle near rivers, springs, lakes and wells (wet-point sites).
• Relief: flat, gently sloping and well-drained land is preferred; steep slopes and flood-prone or marshy ground are avoided (dry-point sites).
• Fertile soil: good farmland attracts settlement because it supports food production.
• Others: availability of minerals, good transport routes, security/defence, and a favourable climate.

(c) Four functions of settlements (with examples)

• Administrative / political function - seat of government, e.g. Abuja.
• Commercial / trading function - major markets and business centres, e.g. Lagos, Onitsha, Kano.
• Industrial / mining function - manufacturing or mining towns, e.g. Warri (oil), Jos (tin mining).
• Educational / religious function - university or religious centres, e.g. Ile-Ife, Mecca, Jerusalem. (Others include port, tourist and residential functions.)

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(a) Five ways transportation contributes to economic development

• Movement of goods and raw materials: It carries raw materials to factories and finished goods to markets, keeping industries running.
• Opening up of remote areas: Roads and railways make interior and rural areas accessible, allowing their resources to be exploited and developed.
• Promotion of trade and commerce: It links producers with consumers within the country and abroad, widening the market and encouraging both internal and international trade.
• Creation of employment: The building, operation and servicing of transport systems provide jobs and incomes for many people.
• Encouragement of agriculture and industry: It enables farmers to sell perishable produce quickly, attracts industries to accessible sites, and promotes tourism and the growth of towns.

(b) Five factors that affect transport development

• Relief: Rugged mountains, steep slopes and valleys make road and rail construction difficult and costly, while flat land is easy to develop.
• Climate: Heavy rainfall, floods, snow or fog damage routes and disrupt movement.
• Nature of the land / drainage: Swamps, marshes, deserts and large rivers hinder construction and require costly bridges and drainage.
• Availability of capital and technology: Transport projects are expensive; shortage of funds and technical skill slows their development.
• Level of economic activity and population: Densely populated and economically active areas attract more transport routes, while sparsely settled areas have few. (Government policy also matters.)

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(a) Map of Africa showing major crude-oil producing areas

(b) Economic importance of crude oil to Nigeria

1. Foreign-exchange earnings: Export of crude oil brings foreign currency into Nigeria, which is used to pay for imports and international obligations.
2. Government revenue: Royalties, petroleum tax, licences and export duties from oil companies provide substantial revenue for the Federal Government.
3. Employment and industrial raw materials: Oil exploration, drilling, refining, transport and marketing employ many workers. Crude oil also supplies raw materials for petrochemical industries producing plastics, lubricants, fertilisers, bitumen and other products.

(c) Problems facing crude-oil production in Nigeria

1. Oil-pipeline vandalism and theft: Damage to pipelines causes loss of crude oil, production shutdowns and expensive repairs.
2. Militancy and conflict in the Niger Delta: Conflict between host communities, militant groups and oil companies may disrupt drilling operations and endanger workers.
3. Difficult terrain and poor transport: Much of the Niger Delta is swampy, densely forested and crossed by creeks, making the movement of workers, machinery and crude oil difficult and costly.

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(a) Outline map of Nigeria showing fishing areas and towns

Key: ● Inland fishing area and town; ▲ Offshore fishing area and town.

(b)(i) Methods of fishing in Nigeria

1. Use of nets, including cast nets and seine nets.
2. Use of hooks and lines.
3. Use of traps or baskets.

Other acceptable methods include the use of spears and trawlers.

(b)(ii) Types of fish caught

1. Tilapia
2. Catfish
3. Mackerel
4. Croaker

(c) Benefits of fishing to the Nigerian economy

1. Fish provides a cheap and important source of animal protein for the population.
2. It provides employment and income for fishermen, fish processors, fish sellers and transporters.
3. It supplies raw materials, such as fish oil and fish meal, for industries.
4. It yields revenue to government through licences, taxes and export earnings.
5. It promotes internal and external trade.

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(a) Four types of atmospheric resources

• Sunlight (solar energy / insolation).
• Wind (moving air).
• Rainfall / water vapour (moisture).
• Air itself (its gases, chiefly oxygen, carbon dioxide and nitrogen).

(b) Usefulness of any two of the resources

1. Sunlight (solar energy):

• It provides light and warmth that make the earth habitable and drive the weather.
• It is essential for photosynthesis, by which green plants make food, so it is the basis of all agriculture and food chains.
• It is harnessed as solar energy for heating, drying crops, and generating electricity through solar panels.

2. Wind (moving air):

• It is used to generate power through windmills and wind turbines for pumping water and producing electricity.
• It drives sailing vessels and aids ventilation and the drying of crops and clothes.
• It aids pollination and seed dispersal of plants and transports moisture that brings rainfall.

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(a) Two differences between the Greek and Koppen systems

(b) Four major features of Koppen's system

• It uses quantitative data - fixed values of temperature and rainfall to define each type.
• It uses a system of letter symbols (A, B, C, D, E, plus small letters) for the main groups and sub-groups.
• It links each climate with its natural vegetation.
• It recognises five main climatic groups: A (tropical rainy), B (dry), C (warm temperate), D (cold temperate) and E (polar).

(c) Four features of the Tropical Rainforest (Equatorial, Af) climate

• High and uniform temperatures throughout the year, averaging about \(27^\circ\text{C}\), with a very small annual range (about \(2-3^\circ\text{C}\)).
• Heavy rainfall all year round, over 1500-2000 mm, with no real dry season (every month exceeds 60 mm).
• High relative humidity (often above 80 per cent) and heavy convectional rainfall, usually in the afternoons.
• Double rainfall maxima associated with the twice-yearly overhead sun, and generally still, calm air (the doldrums) with dense evergreen forest.

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(a)(i) Enlarging square ABCD to twice its size

Divide the original square ABCD into a grid of equal small squares. Draw a new square whose sides are twice as long, giving an outline of \(18\,\text{cm}\) by \(18\,\text{cm}\), and rule the same grid on it so that each small square is doubled in side. Copy the detail from each small square of the original into the corresponding enlarged square, keeping the same relative positions.

(a)(ii) New scale

(b) On the enlarged outline, mark and name, using the correct conventional signs: (i) the two main roads; (ii) the settlement of Egbe; (iii) a spot height.

(c) From the contour lines, identify the land lying below 1000 ft and shade that area evenly.

(d) Three man-made features along the minor road between Oda Pete and Ogga

• The settlement of Omi.
• The school at Oda Pete.
• Footpaths and farmlands (a minor road junction is also present).

(e) Influence of relief on the location of settlements

• There are no settlements on the hilly areas because of the difficulty of building and movement.
• Settlements are located in the pass between two highland areas, for example between Ogbe and Egbe, and in the lowland areas.
• There is no settlement on the crest of the north-south ridge because of its ruggedness.
• Settlements are located on the gentle slopes, for example Oda Pete, Omi and Ogga.

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(a) Outline map of Africa

Key locations shown on the map:

• Equatorial climate: Congo Basin, around the Equator in Central Africa. Town: Kisangani.
• Tropical continental climate: Sudan Savanna belt of West Africa. Town: Kano.
• Mediterranean climate: the north-western coastal fringe of Africa, especially Morocco.

(b)(i) The vegetation associated with the Tropical Continental Climate is tropical grassland (savanna).

(b)(ii) Adaptations of savanna vegetation to the climatic conditions

1. Many trees develop long tap roots which reach water deep in the ground during the long dry season.
2. Some plants have fleshy stems, trunks or roots for storing water for use in the dry season.
3. Trees commonly have thick bark and tough leaves, which reduce water loss and protect them from bush fires.
4. Many plants have small, leathery or needle-shaped leaves, reducing the rate of transpiration.
5. Some trees shed their leaves during the dry season to conserve water.
6. Grasses and some plants have deep, durable root systems or underground stems which survive drought and regenerate rapidly when the rains begin.

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Explanatory notes (any two)

(a) Rift valley

A rift valley is a long, narrow, steep-sided trough formed when a block of land sinks (subsides) between two roughly parallel faults, or when the land on either side is uplifted. It is produced by tensional (pulling apart) forces in the earth's crust. The sunken block is called a graben. Rift valleys often contain long, deep lakes. The best example is the East African (Great) Rift Valley, which runs from the Red Sea through Ethiopia and Kenya, containing lakes such as Lake Turkana and Lake Malawi.

Diagram: a cross-section showing a central down-thrown block (graben) bounded by two normal faults, with the flanks standing higher.

(b) Horst

A horst is an upstanding block of land bounded by two roughly parallel faults, formed when the middle block is uplifted or when the blocks on either side sink. It is the opposite of a graben and results from either tensional or compressional forces. It appears as a block or fault mountain with steep sides and a fairly flat top. Examples include the Ruwenzori and the Vosges and Black Forest highlands of Europe.

Diagram: a cross-section showing a central up-thrown block standing above two down-thrown blocks on either side.

(c) Volcanic mountain

A volcanic mountain is a mountain built up by the accumulation of lava, ash and other materials ejected through a vent from the interior of the earth during volcanic eruptions. As successive eruptions pile up material around the vent, a cone with a crater at the top is formed. Examples include Mount Cameroon, Kilimanjaro and Mount Fuji.

Diagram: a cone showing the central vent (pipe), a magma chamber below, layers of lava and ash, and a crater at the summit.

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(a) Outline map of Nigeria showing the forest belts, towns and Lake Chad

Key: Mangrove (salt-water swamp) forest: Port Harcourt; Freshwater swamp forest: Warri; Tropical rainforest (high forest): Benin City. Lake Chad is shown at the north-eastern boundary of Nigeria.

(b) Characteristics of the tropical rainforest (high forest)

1. It consists of very tall evergreen broad-leaved trees, commonly reaching about 60 m in height.
2. There is a great variety of tree species rather than pure stands. Important species include iroko, mahogany, obeche and walnut.
3. The vegetation has distinct layers, namely upper, middle and lower storeys. The closed canopy admits little sunlight to the forest floor, so undergrowth is sparse. Buttress roots, lianas, climbers and epiphytes are common.

(c) Importance of the forest belts to Nigeria

1. They provide timber and poles for building, furniture making, paper production and other industries.
2. They supply firewood and charcoal for domestic fuel, as well as useful products such as fruits, nuts, rubber and medicinal herbs.
3. They conserve wildlife and provide sites for tourism; timber exports also earn foreign exchange for Nigeria.

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(a) Outline map of Africa

(b) Position and size of Africa in relation to other continents

Position

• Africa lies almost centrally between the other continents and is almost bisected by the Equator into Northern and Southern Africa.
• It lies approximately between latitudes 37°N and 35°S, and longitudes 15°W and 51°E. The meridian of about 20°E nearly divides it into eastern and western parts.
• It is bounded to the north by the Mediterranean Sea, which separates it from Europe.
• To the north-east it is bounded by the Red Sea and Gulf of Aden, which separate it from Asia. Africa is connected to Asia at the Isthmus of Suez.
• It is bounded by the Atlantic Ocean to the west and by the Indian Ocean to the east and south-east.
• It is the most tropical continent because about three-quarters of its land area lies between the Tropics of Cancer and Capricorn.

Size

• Africa is the second-largest continent after Asia.
• It has an area of about 30 to 31 million km², approximately one-fifth of the world’s land surface.
• It is about two-thirds the size of Asia and is larger than Europe, North America, South America and Australia.
• It extends for about 8,000 km from north to south and about 7,000 km from east to west.

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(a) Traversing is a method of surveying in which a series of connected straight lines is measured, with the length and bearing of each line recorded in order to fix the positions of points.

(b) Plotting the traverse

Scale: 1 cm represents 50 m.

Line	Length (m)	Bearing	Length on plan (cm)
AB	100	70°	2.0
BC	350	120°	7.0
CD	120	85°	2.4
DE	75	55°	1.5

The plotted traverse is:

(c) The distance from A to E along the traverse line is the sum of all the line lengths:

\[AE = AB+BC+CD+DE\]

\[=100+350+120+75=\boxed{645\text{ m}}\]

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(a) What are sedimentary rocks?

Sedimentary rocks are rocks formed from the accumulation, compaction and cementation (lithification) of sediments, that is, particles of older rocks, mineral matter or the remains of plants and animals, usually deposited in layers or strata by water, wind or ice.

(b) Three classes according to mode of formation

• Mechanically-formed (clastic) sedimentary rocks - e.g. sandstone, conglomerate, shale.
• Chemically-formed sedimentary rocks - e.g. rock salt, gypsum, some limestones.
• Organically-formed (biogenic) sedimentary rocks - e.g. coal, chalk, coral limestone.

(c) Description of one class - Mechanically-formed sedimentary rocks

These are formed from fragments (detritus) of pre-existing rocks that have been broken down by weathering and erosion. The particles are transported by rivers, wind or ice and deposited in layers. Over time the weight of overlying material compacts them and mineral cement binds the grains together. They are classified by grain size: coarse (gravel forming conglomerate), medium (sand forming sandstone) and fine (mud and clay forming shale). They are typically arranged in visible strata (bedding planes).

(d) Four ways sedimentary rocks are important to man

• They are the main source of fossil fuels - coal, crude oil and natural gas.
• They yield valuable minerals and building materials such as limestone (for cement), sandstone, clay, gypsum and rock salt.
• They form fertile soils and often contain underground water (aquifers) used for water supply and agriculture.
• They preserve fossils that help geologists in the study of earth history and in the search for petroleum and other resources.

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(a)(i) Definition of drought

Drought is a long, continuous period of abnormally dry weather, marked by a serious shortage of rainfall well below the normal amount for an area, leading to acute scarcity of water for plants, animals and human beings.

(a)(ii) Two areas affected by drought

• The Sahel region of West Africa (e.g. northern Nigeria, Niger, Chad, Mali).
• The Horn of Africa / East Africa (e.g. Ethiopia, Somalia, Kenya).

(b) Three effects of drought

• Crop failure and famine: Lack of rain causes crops to wither and die, leading to food shortage, hunger and even death.
• Death of livestock and loss of grazing: Pasture and water dry up, so animals die, ruining the pastoralists' livelihood.
• Water shortage and desertification: Rivers, wells and reservoirs dry up, the land becomes bare, soil erosion increases and the desert advances (desertification), forcing migration of people and animals.

(c) Three ways drought can be reduced

• Afforestation and control of desertification by planting trees and shelter belts to check wind erosion and improve rainfall.
• Construction of dams, boreholes and irrigation schemes to store water and provide it during dry periods.
• Water conservation and good land-management practices such as controlled grazing, mulching and prevention of bush burning, together with cloud seeding and public enlightenment.

Maelezo ya Majibu

(a) Outline map of Nigeria showing cattle rearing and movement

The principal cattle-rearing zone is the Sudan/Sahel savanna belt of northern Nigeria. The map shows Sokoto, Kano and Maiduguri within this zone, and a south-westward arrow indicating movement of cattle from the northern rearing zone to Lagos, a major consuming area.

(b) Problems of cattle rearing in Nigeria

1. Dry-season shortage of pasture and water: rainfall is low and seasonal in the far north; pasture dries up and water sources may fail during the long dry season.
2. Pests and diseases: ticks, tsetse flies and diseases such as trypanosomiasis, rinderpest and foot-and-mouth disease cause illness, deaths and reduced productivity.
3. Poor facilities and management: there are inadequate ranches, grazing reserves, veterinary services, capital, transport and cold-storage facilities. Long trekking also causes weight loss and may lead to clashes with farmers and cattle rustling.

(c) Measures being taken to solve the problems

1. Grazing reserves and ranches are being developed, with improved pasture, fodder cultivation, boreholes, dams and irrigation to provide dry-season water and feed.
2. Veterinary clinics, vaccination programmes, disease surveillance and control of ticks and tsetse flies are being provided. Cross-breeding is also used to obtain healthier and more productive animals.
3. Extension services educate herders on modern animal management, while loans and other financial assistance support ranch development.
4. Feeder roads, cattle trucks and rail transport reduce long-distance trekking. Refrigerated vehicles, abattoirs and cold stores help preserve meat and dairy products.
5. Designated grazing routes and reserves, together with security measures, help reduce farmer-herder conflict and cattle theft.