Part 2, Chapter 1: Understanding the World through Geography

Key idea 1: Every map has some distortion — The Earth is an oblate spheroid: slightly flattened at the poles and bulging at the equator. So a flat map gets either shapes or sizes wrong somewhere. Every map is a compromise, so we should look at more than one projection.

• Easy: An orange peel cannot be laid flat, so maps have distortion.
• Medium: Greenland looks huge on the Mercator map.
• Exam-type: Which projection helps navigation? — Mercator, because it preserves direction.

In the figure: No map is perfect; each has a weakness.

Key idea 2: Mercator and Robinson — The Mercator projection keeps shape and direction, so it helps navigation, but it greatly inflates size near the poles (Greenland looks as big as Africa). The Robinson projection balances shape and size. In reality Greenland is smaller than India. Professionals use latitude and longitude for precision.

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Key idea 1: The blue planet — Oceans cover about 71 per cent of the Earth’s surface and hold 97 per cent of its water. They absorb heat and release it slowly, and add moisture that makes clouds and rain. The five oceans: Indian, Pacific, Arctic, Atlantic and Southern. Tiny organisms like plankton give us almost half our oxygen.

• Easy: The Gulf Stream keeps the UK warm.
• Medium: The Mariana Trench is the deepest ocean trench.
• Exam-type: Why call a reef the ‘rainforest of the sea’? — It gives food and shelter to many species.

In the figure: Oceans support climate, food and life.

Key idea 2: Currents and trenches — Warm currents carry water from the equator toward the poles; cold currents carry it the other way. The Gulf Stream brings warm water to western Europe, so the UK is warmer than other places at the same latitude. Deep V-shaped parts of the seafloor are trenches; the Mariana Trench is the deepest, with Challenger Deep over 11,000 metres down. With no light, life there makes food from chemicals.

Key idea 3: The Great Barrier Reef — A reef is a ridge at or near the sea surface. Reefs are called the ‘rainforests of the sea’ and shelter about a quarter of ocean species. Off north-eastern Australia the Great Barrier Reef stretches about 2,000 km over roughly 350,000 sq km; it is a UNESCO World Heritage Site. Overfishing, pollution and climate change bleach and kill corals.

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Key idea 1: Five types — Sea (Arabian Sea), gulf (Persian Gulf), bay (Bay of Bengal), strait (Strait of Malacca) and canal (Suez Canal). The Bay of Bengal is the world’s largest bay; bays give ports safe shelter.

• Easy: The Arabian Sea is a sea; the Bay of Bengal is a bay.
• Medium: Malacca is a strait.
• Exam-type: Why is the Suez Canal important? — It shortens the sea route between India and Europe.

In the figure: The Suez Canal shortened the India–Europe voyage.

Key idea 2: The Suez Canal — The Suez Canal opened in 1869. It joins the Red Sea and the Mediterranean and gives the shortest sea route from India to Europe. The Persian Gulf has been important for India–Europe trade for thousands of years.

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Key idea 1: Asia — The Tibetan Plateau is the highest and largest plateau on Earth, north of the Himalayas, formed by the collision of the Indo-Australian and Eurasian plates. It is the source of the Indus, Brahmaputra and Yangtze and is called the ‘Third Pole’. The Gobi Desert lies in Mongolia (partly in north China); it is a cold desert where winter temperatures fall to minus 30°C. The Eurasian Steppes stretch over 8,000 km and store carbon; the Urals mark the border of Asia and Europe.

• Easy: The Tibetan Plateau averages over 4,500 m high.
• Medium: The Gobi is a cold desert.
• Exam-type: Why is the European Plain good for farming? — Fertile soil and rivers.

In the figure: Plateaus, deserts, grasslands and mountains affect life.

Key idea 2: Europe — The European Plain is one of the world’s largest flatlands. Fertile soil, wheat, barley, rye, potatoes, rivers and coal, oil and gas made it rich; cities like Moscow, Berlin and Paris grew there. The Alps are a 1,200 km crescent-shaped range with Mont Blanc as a famous peak; they feed the Rhine and tributaries of the Danube. Edelweiss is the flower of the Alps.

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Key idea 1: Africa — The Sahara is the largest hot desert; its rainfall is under 25 cm. The Nile, about 6,650 km, is the longest river and was the cradle of ancient Egyptian civilisation. The savannah is home to elephants, lions, zebras and giraffes.

• Easy: The Nile is the world’s longest river.
• Medium: The Amazon is the largest river by volume.
• Exam-type: Why is Antarctica called a desert? — It gets very little precipitation.

In the figure: Each continent’s features shape life there.

Key idea 2: South America — The Andes are the continent’s largest range, with Aconcagua and Bolivia’s Uyuni Salt Flats. The Amazon is the world’s largest river by volume, and its basin holds the Amazon Rainforest. The Atacama is one of the driest places; discarded fast-fashion clothes pile up there in huge amounts.

Key idea 3: North America — The Colorado Plateau covers over 330,000 sq km and holds the Grand Canyon. The Rockies stretch about 4,800 km. The Appalachians are among the oldest mountains. The five Great Lakes are a chain of freshwater lakes used for shipping.

Key idea 4: Australia and Antarctica — Much of Australia is desert (the Great Australian Desert), where indigenous people have lived for over 25,000 years. The largest desert is Antarctica, over 14 million sq km; it is also the coldest desert.

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Key idea 1: Effects of human actions — Deforestation, overuse of resources and pollution cause desertification, biodiversity loss and climate change. E.g. the Amazon is at risk from deforestation, reefs bleach from pollution, and the Atacama has clothing waste.

• Easy: Deforestation destroys habitats.
• Medium: Wolves were introduced to Yellowstone in 1995.
• Exam-type: What is sustainable development? — Meeting today’s needs while keeping resources for future generations.

In the figure: One action’s effect passes along a chain.

Key idea 2: Lesson from Yellowstone — In Yellowstone National Park overgrazing by elk caused imbalance. Wolves were introduced in 1995; they reduced the elk and plants returned. This shows ecological balance can be restored.

Key idea 3: Sustainable development — Studying world geography helps us see natural features and their links to human life so we can use resources wisely. Land, water and climate are all connected.

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