Grade 10 Geography - Textbook Notes

Grade 10 Geography - Textbook Notes

Taking Care of Textbooks

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Unit One: Landforms of Africa

• The textbook will examine Africa’s landforms, climate, natural resource bases, population, economic and cultural activities, human environment interactions, geographic issues and public concerns, geospatial information, and data processing.
• Successful completion of the subject helps develop understanding and knowledge of basic geographic concepts, principles, and theories focusing on Africa.
• Unit Outcomes:
  • Develop general idea on major landforms of the world.
  • Identify major landforms and their spatial distribution in Africa.
  • Describe the major landscape features of Africa.
  • Recognize spatial variations in the distribution of major landforms in Africa.

1.1 Overview of the World’s Major Landforms

• Key Terms: Continents, Landforms, Mountains, Oceans, Peninsula, Plain, Plateaus, Plate tectonic, Volcanic activities
• Landforms are physical features on the Earth’s surface that form terrain of an area.
• Major landforms: mountains, plateaus, and plains.
• Minor landforms: hills, gorges, valleys, and basins.
• Tectonic plate movement and volcanic activities (internal processes) can create landforms (e.g., mountains and hills).
• Erosion by water and wind (external processes) can create minor landforms (e.g., gullies, river valleys, and gorges).
• These processes happen over long periods, sometimes millions of years.
• Example: Abbay Gorge (cuts 1000 m deep).
• The surface of the Earth is covered by land and water.
• Landforms make up continents, and water forms oceans.
• Continents are the largest landmasses.
• The seven continents from largest to smallest: Asia, Africa, North America, South America, Antarctica, Europe, and Oceania (Australia).
• Oceans are large areas of salt water between continents.
• Five oceans: Arctic, Atlantic, Indian, Pacific, and Southern.
• Oceans cover 71% of the Earth’s surface.
• The Pacific Ocean is the largest and deepest, covering one-third of the Earth’s surface.
• Oceans are important for creating coastal land features: islands, peninsulas, isthmuses.
• An island is a piece of ground completely surrounded by water.
• The largest island in the world is Greenland. (Australia is considered a continent).
• A peninsula is a piece of land with water on three sides, connected on the fourth side to the mainland (e.g., Italy and Florida).
• An isthmus is a narrow strip of land with water on both sides connecting two larger pieces of land (e.g., Isthmus of Panama).

I. Mountain

• Mountains are the largest elevated and most recognizable landforms with steep sides and high peaks.
• Hills are smaller, less steep landforms around mountains.
• Mountains are formed when rock layers are pushed together.
• Valleys are the low areas between mountains.
• Mountains may also be formed by volcanic activity.
• Mt. Everest is the highest landform, located in the Himalayas between Nepal and Tibet, measuring 8,849 meters above sea level.
• The Himalayas formed 40 to 50 million years ago when the Indian tectonic plates collided with the Eurasian plate.
• The Mariana Trench is the deepest landform on Earth, located in the South Pacific Ocean.

II. Plain

• Plains are large areas of flat low land with no hills or mountains.
• Example: The Great Plains in the mid United States.
• Plains are important areas for crop cultivation and animal husbandry (ranch).

III. Plateaus

• Plateaus are large areas of raised land that are flat on top.
• Formed by volcanic activity: magma pushes the land upwards.
• Plateaus may stand alone or be close to other plateaus.

1.2 Location and Related Features of Africa

• Key Terms: Continents, Equator, Surface area, Sovereign state
• Africa is bounded by the Mediterranean Sea, the Red Sea, the Gulf of Aden, the Indian Ocean, and the Atlantic Ocean.
• It is divided in half by the Equator.
• Africa is the second largest and second most populous continent.
• Area: 30.37 million $km^2$ (6% of Earth’s total surface area and 20% of its land area).
• Population (2020): 1.3 billion (16% of the world’s population).
• Africa has 54 recognized sovereign states.
• Division across the equator makes climatic and physical conditions in the north repeat in the south (e.g., Kalahari Desert similar to Sahara).

1.3 Major Landforms of Africa

• Key Terms: Atlas Mountains, Benguela, Congo Basin, Deserts, Ecosystems, External processes, Graben, Great Escarpment, Great Karoo, Highveld, Hills, Island, Isthmus, Macroclimate, Microclimate, Rift Valley, The Sahara, The Sahel, The Savanna, Tropical rainforest.
• Landforms are the results of volcanic and tectonic processes.
• Landforms affect human perception and interactions with the environment.
• Landforms provide a physical context for describing the landscape, topography, and ecological units.
• Ecosystems develop within landform regions.
• Material and energy flows occur within the landform system.
• Landforms affect and modify climate (macroclimate and microclimate).
• Effects of landforms on ecosystem patterns and processes:
  1. Landform attributes (elevation, slope, aspect) determine ecological potential.
  2. Landform regions affect the flow of organisms, energy, and material.
  3. Landform regions affect the spatial pattern of non-geomorphic disturbance (fire and wind).
  4. Landforms may resist changes, protecting biotic features and processes.
• Four significant landform regions in Africa:
  • African Alpine System
  • African massif
  • East African Highlands and rift system
  • Southern Africa Platform

Table 1.1: Major Regions of Landform in Africa

1.3.1 African Alpine System

• Atlas Mountains:
  • A range of mountains in North Africa extends from Morocco to Tunisia.
  • Forms mountain chains: Anti-Atlas, High Atlas, Middle Atlas, Rif Mountains, Tell Atlas, and Sahara Atlas.
  • Covers the Maghrib region (Morocco, Algeria, and Tunisia).
  • Extends over 2,000 kilometers.
  • Forms a high divide between the Mediterranean Sea (north) and the Sahara Desert (south).

1.3.2 African Massif

• The Sahara is a desert on the African continent.
• Area: 9,200,000 square kilometers (largest hot desert).
• Covers North Africa, from the Atlantic coast (west) to the Red Sea (east).
• Borders the Mediterranean Sea and the Atlas Mountains (north), extending south into Sudan and the Sahel.
• Includes parts of Algeria, Chad, Egypt, Libya, Mali, Mauritania, Morocco, Niger, Sudan, and Tunisia.
• Landscape: covered with sand; reddish sand dunes (erg), desert pavement of pebbles (reg).

• The Sahel is a semiarid region south of the Sahara.
• Forms a transitional zone between the desert and the Sudan region.
• Stretches 5,000 kilometers from Mauritania and Senegal to Somalia.
• Countries in the Sahel: Mauritania, Senegal, Mali, Niger, Nigeria, Burkina Faso, Chad, Sudan and Eritrea.
• Lands are grasslands and savannahs with scrub areas.
• Has natural pasture for livestock.
• Landscape is similar to the savanna type, but merges into desert due to human activities and climate change.

• The Savanna is a transitional region between rainforest and the Sahel grassland.
• A tropical grassland with few trees and shrubs.
• Trees are drought resistant, usually shedding leaves during the dry season to reduce water loss.
• Two important parts: woodland and thorn tree tall grass Savana.
  • Savanna woodland: trees are widely spaced, allowing dense lower layer of grasses.
  • Trees are medium height with flattened crowns, thick bark, often fire resistant.

• Tropical rainforests occur both north and south of the Equator; near the equator they are known as equatorial rainforests.
• Very diverse and contain many plant and animal species.
• High species count: a square kilometer may contain 100 different tree species.
• Dominant vegetation cover: broadleaf evergreen trees.
• Congo Basin rainforest: in Cameroon, Central African Republic, Republic of the Congo, Democratic Republic of the Congo, Gabon, and Equatorial Guinea.
• Rainforest climate: wet all year or with a short dry season; annual rainfall exceeds 2000 to 2250 millimeters; temperature and humidity are high.
• Rapid decomposition, chemical weathering, and leaching make tropical soils acidic and nutrient poor.

1.3.3 East African Highlands and Rift System

• Formed by normal faulting; land stretched by forces moving in opposite direction creating rupture.
• Creates a graben: an elongated block of the Earth’s crust lying between two faults and displaced downward.
• The Rift Valley System extends from the Red Sea through Ethiopia to Lake Victoria, then subdivides into east and west segments to Mozambique.
• Total length: estimated to be 5,600 km.
• Average width: between 32 km and 80 km.
• The Rift Valley lakes are series of lakes in the East African Rift valley that runs through eastern Africa from Ethiopia in the north to Malawi in the south, and includes the African Great Lakes in the south.
• Many of the lakes are freshwater with great biodiversity; others are alkaline or salty.
• The Ethiopian Rift Valley lakes are the northernmost of the African Rift Valley lakes. In central Ethiopia, the Main Ethiopian Rift, also known as the Great Rift Valley, splits the Ethiopian highlands into northwestern and southeastern halves, and the Ethiopian Rift Valley lakes occupy the floor of the rift valley between the two highlands.
• Lake Victoria is the largest lake in Africa.

• Ethiopia has spectacular scenery with a high plateau and a central highland complex.
• Diversity of terrain produces regional variations in climate, natural vegetation, soil, and settlement patterns.
• Ethiopia’s northwestern highlands extend into Eritrea, reaching elevations of more than 2,000 meters above sea level.
• The plateau (Northwestern Highlands) rises on the western scarp of the Great Rift Valley and projects northward from Addis Ababa to the Red Sea coastline in Eritrea.

1.3.4 Southern Africa Platform

• The region south of the Congo and Tanzania is named Southern Africa.
• Has diverse landscape: escarpment, mountains, grassland, and desert.
  *The Tropic of Capricorn runs straight through the middle of the region, indicating that the southern portion is outside the tropics or there is a temperate part in the region.
• The Ukhahlamba (Drakensberg) escarpment is the most recognizable landscape; average altitude is almost 3,000 m above sea level.
• Two important deserts: The Kalahari Desert (mainly in Botswana; grasslands and sand) and the Namib Desert (along the west coast of Namibia). The Namib desert was formed partly because of the cold ocean current nearby.
  *The highveld is the portion of the South African inland plateau; Highveld slopes gently downwards and is bounded by the Great Karoo to the south, the Kalahari Desert to the west and the Bushveld to the north.
• The highveld is home to some the South Africa’s most important commercial farming areas, as well as its largest concentration of metropolitan centers, especially the Gauteng conurbation, which accommodates one-third of South Africa’s population.
• The continuation of the Great Escarpment to the south separates the Highveld from KwaZulu-Natal. The southeastern portion of the Great Escarpment or the Ukhahlamba (Drakensberg) forms the boundary between KwaZulu-Natal and Lesotho.