WAEC SSCE - Geography - 2021 (Practical and Physical Geography)
Swali 1 Ripoti
(a) List three types of sedimentary rocks classified according to their mode of formation.
(b) Name the rocks that are formed when the following undergo metamorphism:
(i) granite;
(ii) clay;
(iii) shale;
(iv) limestone
(c) Outline four differences between Sedimentary and metamorphic rocks.
(a) Three types of sedimentary rocks classified by mode of formation
- Mechanically formed (clastic) rocks - from compacted rock fragments, e.g. sandstone, conglomerate, shale.
- Chemically formed rocks - from precipitation of dissolved minerals, e.g. rock salt, gypsum, some limestone.
- Organically formed rocks - from remains of plants and animals, e.g. coal, coral limestone, chalk.
(b) Rocks formed when the following undergo metamorphism
| Original rock | Metamorphic product |
|---|---|
| (i) Granite | Gneiss |
| (ii) Clay | Slate |
| (iii) Shale | Slate (then schist) |
| (iv) Limestone | Marble |
(c) Four differences between Sedimentary and Metamorphic rocks
| Sedimentary rocks | Metamorphic rocks |
|---|---|
| Formed by deposition and compaction of sediments. | Formed by alteration of existing rocks under heat and pressure. |
| Occur in layers or strata (bedded). | Often show banding or foliation, not true bedding. |
| Usually soft and may contain fossils. | Usually hard, crystalline and fossils are destroyed. |
| Formed at or near the earth's surface. | Formed deep within the crust under great heat and pressure. |
Maelezo ya Majibu
(a) Three types of sedimentary rocks classified by mode of formation
- Mechanically formed (clastic) rocks - from compacted rock fragments, e.g. sandstone, conglomerate, shale.
- Chemically formed rocks - from precipitation of dissolved minerals, e.g. rock salt, gypsum, some limestone.
- Organically formed rocks - from remains of plants and animals, e.g. coal, coral limestone, chalk.
(b) Rocks formed when the following undergo metamorphism
| Original rock | Metamorphic product |
|---|---|
| (i) Granite | Gneiss |
| (ii) Clay | Slate |
| (iii) Shale | Slate (then schist) |
| (iv) Limestone | Marble |
(c) Four differences between Sedimentary and Metamorphic rocks
| Sedimentary rocks | Metamorphic rocks |
|---|---|
| Formed by deposition and compaction of sediments. | Formed by alteration of existing rocks under heat and pressure. |
| Occur in layers or strata (bedded). | Often show banding or foliation, not true bedding. |
| Usually soft and may contain fossils. | Usually hard, crystalline and fossils are destroyed. |
| Formed at or near the earth's surface. | Formed deep within the crust under great heat and pressure. |
Swali 2 Ripoti
(a) Define environmental balance.
(b) With the aid of a diagram, explain the water cycle.
(c) In what three ways is the water cycle beneficial to man?
(a) Environmental balance
Environmental balance is the stable and sustainable state in an ecosystem in which living organisms and non-living components interact through the recycling of matter and the flow of energy without upsetting the system.
(b) Water cycle
The water cycle, or hydrological cycle, is the continuous circulation of water between water bodies, the atmosphere, the land and living things.
Explanation of the diagram
- Heat from the sun causes water in oceans, rivers, lakes and moist land to evaporate into the atmosphere as water vapour.
- Plants also release water vapour through transpiration.
- As the moist air rises and cools, the vapour condenses
- When the droplets become large and heavy, they fall as precipitation, mainly rainfall.
- Some rainwater flows over the land as surface runoff into rivers and back to the sea. Some infiltrates the soil as groundwater and also returns to rivers and the sea. The process then continues.
(c) Three benefits of the water cycle to man
- It supplies fresh water through rainfall, rivers, springs, wells and boreholes for drinking, washing and other domestic uses.
- It provides rainfall and soil moisture needed for agriculture and the growth of crops.
- It replenishes rivers, lakes and reservoirs used for industrial purposes and the generation of hydroelectric power.
Maelezo ya Majibu
(a) Environmental balance
Environmental balance is the stable and sustainable state in an ecosystem in which living organisms and non-living components interact through the recycling of matter and the flow of energy without upsetting the system.
(b) Water cycle
The water cycle, or hydrological cycle, is the continuous circulation of water between water bodies, the atmosphere, the land and living things.
Explanation of the diagram
- Heat from the sun causes water in oceans, rivers, lakes and moist land to evaporate into the atmosphere as water vapour.
- Plants also release water vapour through transpiration.
- As the moist air rises and cools, the vapour condenses
- When the droplets become large and heavy, they fall as precipitation, mainly rainfall.
- Some rainwater flows over the land as surface runoff into rivers and back to the sea. Some infiltrates the soil as groundwater and also returns to rivers and the sea. The process then continues.
(c) Three benefits of the water cycle to man
- It supplies fresh water through rainfall, rivers, springs, wells and boreholes for drinking, washing and other domestic uses.
- It provides rainfall and soil moisture needed for agriculture and the growth of crops.
- It replenishes rivers, lakes and reservoirs used for industrial purposes and the generation of hydroelectric power.
Swali 3 Ripoti
Table X below contains data on the distribution of Groundnut production in four regions of country M in the year 2013. Use the data in the table to answer the questions that follow.
| Country | Groundnut production in metric tones |
| A | 100,000 |
| B | 260,000 |
| C | 200,000 |
| D | 80,000 |
(a) Using the map of country M and a scale of one dot to represent 20,000 metric tonnes, produce dots to represent the data.
(b) State three disadvantages of dot maps.
Map of country M showing groundnut production in the year 2013
| Region | Groundnut production (metric tonnes) |
|---|---|
| A | 100,000 |
| B | 260,000 |
| C | 200,000 |
| D | 80,000 |
(a) Producing the dot map
On a dot map each dot stands for a fixed quantity, here 1 dot = 20,000 metric tonnes. Divide each region's output by 20,000 to find the number of dots to place inside that region on the map of country M:
| Region | Production | Working | Number of dots |
|---|---|---|---|
| A | 100,000 | 100,000/20,000 | 5 dots |
| B | 260,000 | 260,000/20,000 | 13 dots |
| C | 200,000 | 200,000/20,000 | 10 dots |
| D | 80,000 | 80,000/20,000 | 4 dots |
Draw all dots the same size and spread them evenly within each region's boundary (more dots where output is larger, so region B is most crowded and region D least). Add a title and a key stating that one dot represents 20,000 metric tonnes.
(b) Three disadvantages of dot maps
- They are time-consuming and tedious to draw, since every dot must be counted out and placed accurately.
- It is difficult to read exact values from the map, because the reader must count the dots and multiply, and closely spaced dots are hard to count.
- Choosing the dot value is tricky: if the value is too small the map is overcrowded and dots merge, and if too large small quantities cannot be shown, so the map can give a misleading impression of the true distribution within a region.
Maelezo ya Majibu
| Region | Groundnut production (metric tonnes) |
|---|---|
| A | 100,000 |
| B | 260,000 |
| C | 200,000 |
| D | 80,000 |
(a) Producing the dot map
On a dot map each dot stands for a fixed quantity, here 1 dot = 20,000 metric tonnes. Divide each region's output by 20,000 to find the number of dots to place inside that region on the map of country M:
| Region | Production | Working | Number of dots |
|---|---|---|---|
| A | 100,000 | 100,000/20,000 | 5 dots |
| B | 260,000 | 260,000/20,000 | 13 dots |
| C | 200,000 | 200,000/20,000 | 10 dots |
| D | 80,000 | 80,000/20,000 | 4 dots |
Draw all dots the same size and spread them evenly within each region's boundary (more dots where output is larger, so region B is most crowded and region D least). Add a title and a key stating that one dot represents 20,000 metric tonnes.
(b) Three disadvantages of dot maps
- They are time-consuming and tedious to draw, since every dot must be counted out and placed accurately.
- It is difficult to read exact values from the map, because the reader must count the dots and multiply, and closely spaced dots are hard to count.
- Choosing the dot value is tricky: if the value is too small the map is overcrowded and dots merge, and if too large small quantities cannot be shown, so the map can give a misleading impression of the true distribution within a region.
Swali 4 Ripoti
(a) What is a Great Circle?
(b) Outline three characteristics of a Great Circle.
(c) If the time at longitude 100°E was 5 a.m on Monday, 11th April 2011, what was the
(i) time at longitude 10°W
(ii) day at longitude 10°W
(iii) date at longitude 10°W.
(a) What is a Great Circle?
A Great Circle is any circle drawn on the surface of the earth whose plane passes through the centre of the earth, thereby dividing the globe into two equal halves (hemispheres). It has the same circumference as the earth. Examples are the Equator and every pair of opposite meridians of longitude.
(b) Three characteristics of a Great Circle
- Its plane passes through the centre of the earth and divides the earth into two equal halves.
- It has the largest circumference possible on the globe, equal to that of the earth.
- The arc of a Great Circle gives the shortest distance between any two points on the earth's surface (used in air and sea navigation).
(c) Time calculation
Given time at 100°E = 5 a.m. on Monday, 11th April 2011. Find values at 10°W.
Difference in longitude \( = 100^\circ + 10^\circ = 110^\circ \).
Since \( 1^\circ = 4 \) minutes of time:
\[ 110 \times 4 = 440 \text{ minutes} = 7 \text{ hours } 20 \text{ minutes} \]
Because 10°W lies west of 100°E, its time is behind, so we subtract:
\[ 5{:}00 \text{ a.m. Monday} - 7\text{h }20\text{m} = 9{:}40 \text{ p.m.} \]
(i) Time at 10°W: 9:40 p.m. (21:40 hours).
(ii) Day at 10°W: Sunday.
(iii) Date at 10°W: 10th April 2011.
Maelezo ya Majibu
(a) What is a Great Circle?
A Great Circle is any circle drawn on the surface of the earth whose plane passes through the centre of the earth, thereby dividing the globe into two equal halves (hemispheres). It has the same circumference as the earth. Examples are the Equator and every pair of opposite meridians of longitude.
(b) Three characteristics of a Great Circle
- Its plane passes through the centre of the earth and divides the earth into two equal halves.
- It has the largest circumference possible on the globe, equal to that of the earth.
- The arc of a Great Circle gives the shortest distance between any two points on the earth's surface (used in air and sea navigation).
(c) Time calculation
Given time at 100°E = 5 a.m. on Monday, 11th April 2011. Find values at 10°W.
Difference in longitude \( = 100^\circ + 10^\circ = 110^\circ \).
Since \( 1^\circ = 4 \) minutes of time:
\[ 110 \times 4 = 440 \text{ minutes} = 7 \text{ hours } 20 \text{ minutes} \]
Because 10°W lies west of 100°E, its time is behind, so we subtract:
\[ 5{:}00 \text{ a.m. Monday} - 7\text{h }20\text{m} = 9{:}40 \text{ p.m.} \]
(i) Time at 10°W: 9:40 p.m. (21:40 hours).
(ii) Day at 10°W: Sunday.
(iii) Date at 10°W: 10th April 2011.
Swali 5 Ripoti
(a) List three landforms associated with coastal erosion.
(b) Explain the following processes of wave erosion:
(i) hydraulic action:
(ii) COrrasion
(a) Three landforms associated with coastal erosion
- Cliffs (and the wave-cut platform at their base).
- Caves, arches and stacks (and stumps).
- Headlands and bays (also blow holes and geos).
(b) Processes of wave erosion
(i) Hydraulic action: this is the erosion caused by the sheer force of moving water. As waves break against a cliff, water is forced into cracks and joints in the rock. The air trapped in these cracks is suddenly compressed and then released as the wave retreats. This repeated compression and expansion weakens and shatters the rock, breaking pieces away. No rock fragments are needed; it is the power of the water and trapped air alone.
(ii) Corrasion (abrasion): this is the wearing away of the coast by the load carried by the waves. Waves pick up sand, pebbles and boulders and hurl them against the cliff face and drag them over the shore platform. This grinding and scraping action, like sandpaper, chips and smooths the rock, deepening notches and enlarging caves.
Maelezo ya Majibu
(a) Three landforms associated with coastal erosion
- Cliffs (and the wave-cut platform at their base).
- Caves, arches and stacks (and stumps).
- Headlands and bays (also blow holes and geos).
(b) Processes of wave erosion
(i) Hydraulic action: this is the erosion caused by the sheer force of moving water. As waves break against a cliff, water is forced into cracks and joints in the rock. The air trapped in these cracks is suddenly compressed and then released as the wave retreats. This repeated compression and expansion weakens and shatters the rock, breaking pieces away. No rock fragments are needed; it is the power of the water and trapped air alone.
(ii) Corrasion (abrasion): this is the wearing away of the coast by the load carried by the waves. Waves pick up sand, pebbles and boulders and hurl them against the cliff face and drag them over the shore platform. This grinding and scraping action, like sandpaper, chips and smooths the rock, deepening notches and enlarging caves.
Swali 6 Ripoti
(a) List three landforms that are associated with extrusive volcanic action.
(b) With the aid of a diagram, describe the characteristics and mode of formation of laccoliths.
(a) Landforms associated with extrusive volcanic action
- Lava plains or lava plateaux.
- Shield volcanoes (basic lava cones).
- Composite cones (strato-volcanoes).
(b) Laccolith
A laccolith is a concordant intrusive igneous body formed when viscous magma is injected between sedimentary rock beds. It has a nearly flat base and a rounded or dome-shaped upper surface, giving it a mushroom-like form.
Diagram of a laccolith
Characteristics
- It is an intrusive igneous landform, formed below the Earth's surface.
- It lies concordantly, that is, generally parallel to the bedding planes of the surrounding sedimentary rocks.
- It has a broad, almost flat floor and a convex, dome-shaped roof.
- It arches and uplifts the overlying sedimentary strata.
- It is commonly fed from below by a narrow pipe-like conduit or dyke.
- It is composed of hard igneous rock and may stand out as a rounded hill or upland after denudation removes the cover rocks.
Mode of formation
- Viscous magma rises from the interior through a line of weakness or a pipe-like conduit.
- On reaching a resistant rock layer, the magma cannot easily continue vertically upward.
- It therefore spreads sideways along a bedding plane between sedimentary strata.
- Because the magma is thick and does not spread far, it accumulates locally and pushes the overlying beds upward into a dome.
- The magma cools and solidifies beneath the arched strata to form a laccolith.
- Subsequent erosion may remove the overlying sedimentary rocks and expose the resistant laccolith as an upland feature.
Maelezo ya Majibu
(a) Landforms associated with extrusive volcanic action
- Lava plains or lava plateaux.
- Shield volcanoes (basic lava cones).
- Composite cones (strato-volcanoes).
(b) Laccolith
A laccolith is a concordant intrusive igneous body formed when viscous magma is injected between sedimentary rock beds. It has a nearly flat base and a rounded or dome-shaped upper surface, giving it a mushroom-like form.
Diagram of a laccolith
Characteristics
- It is an intrusive igneous landform, formed below the Earth's surface.
- It lies concordantly, that is, generally parallel to the bedding planes of the surrounding sedimentary rocks.
- It has a broad, almost flat floor and a convex, dome-shaped roof.
- It arches and uplifts the overlying sedimentary strata.
- It is commonly fed from below by a narrow pipe-like conduit or dyke.
- It is composed of hard igneous rock and may stand out as a rounded hill or upland after denudation removes the cover rocks.
Mode of formation
- Viscous magma rises from the interior through a line of weakness or a pipe-like conduit.
- On reaching a resistant rock layer, the magma cannot easily continue vertically upward.
- It therefore spreads sideways along a bedding plane between sedimentary strata.
- Because the magma is thick and does not spread far, it accumulates locally and pushes the overlying beds upward into a dome.
- The magma cools and solidifies beneath the arched strata to form a laccolith.
- Subsequent erosion may remove the overlying sedimentary rocks and expose the resistant laccolith as an upland feature.
Swali 7 Ripoti
Explain how the following factors affect the temperature of a place:
(a) altitudes
(b) distance from the sea
(c) Slope and aspect
How the following factors affect the temperature of a place
(a) Altitude: temperature falls with increasing height above sea level, at an average rate of about 6.5 °C per 1000 m (the normal lapse rate). The air near the ground is warmed from below by the earth's surface, and it is also denser and holds more heat, dust and moisture. Higher up the air is thinner, drier and further from the heated surface, so it loses heat quickly. This is why highland areas such as Jos and mountain tops are cooler than surrounding lowlands on the same latitude.
(b) Distance from the sea (continentality): the sea heats and cools more slowly than the land. Coastal places have a small (moderate) temperature range because the sea warms them in winter and cools them in summer. Places far inland have a large temperature range, with very hot days/summers and cold nights/winters, because land heats and cools rapidly. Sea and land breezes also moderate coastal temperatures.
(c) Slope and aspect: the direction a slope faces (aspect) and its angle control how much insolation it receives. In the northern hemisphere, south-facing slopes face the sun and are warmer, while north-facing slopes are cooler and shaded (the reverse in the southern hemisphere). Slopes at right angles to the sun's rays receive concentrated heat over a small area and become warmer, while gentle or shaded slopes receive slanting rays spread over a wider area and stay cooler.
Maelezo ya Majibu
How the following factors affect the temperature of a place
(a) Altitude: temperature falls with increasing height above sea level, at an average rate of about 6.5 °C per 1000 m (the normal lapse rate). The air near the ground is warmed from below by the earth's surface, and it is also denser and holds more heat, dust and moisture. Higher up the air is thinner, drier and further from the heated surface, so it loses heat quickly. This is why highland areas such as Jos and mountain tops are cooler than surrounding lowlands on the same latitude.
(b) Distance from the sea (continentality): the sea heats and cools more slowly than the land. Coastal places have a small (moderate) temperature range because the sea warms them in winter and cools them in summer. Places far inland have a large temperature range, with very hot days/summers and cold nights/winters, because land heats and cools rapidly. Sea and land breezes also moderate coastal temperatures.
(c) Slope and aspect: the direction a slope faces (aspect) and its angle control how much insolation it receives. In the northern hemisphere, south-facing slopes face the sun and are warmer, while north-facing slopes are cooler and shaded (the reverse in the southern hemisphere). Slopes at right angles to the sun's rays receive concentrated heat over a small area and become warmer, while gentle or shaded slopes receive slanting rays spread over a wider area and stay cooler.
