Class 6 ยท Social Science ยท Exploring Society
Chapter 2 ๐
Chapter 2 ๐
Oceans and Continents
Detailed, colourful revision notes โ everything you need before your test!
Chapter Contents
1. Distribution of Water & Land
Seen from space, Earth looks mostly blue โ that's why it's nicknamed the "Blue Planet". Most of that blue is water.
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Fig 1: About three-fourths of Earth's surface is water
A large water body is an ocean. A large body of land is a landmass; a large continuous expanse of land is a continent.
Water and land are not shared equally between hemispheres โ one hemisphere holds noticeably more water than the other. Oceans and continents together shape Earth's climate and all life on it.
2. The Five Oceans
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Fig 2: The world's five oceans (schematic โ real oceans are all interconnected!)
The five oceans, from largest to smallest: Pacific โ Atlantic โ Indian โ Southern (Antarctic) โ Arctic. In reality, they are all one connected body of water โ the dividing lines are just conventions.
India lies between the Arabian Sea (to the west) and the Bay of Bengal (to the east) โ both are parts of the Indian Ocean, whose limits are Asia (north), Africa (west), and Australia (east).
Marine flora = ocean plant life (algae, seaweed). Marine fauna = ocean animal life (fish, dolphins, whales).
3. Oceans and Disasters
A cyclone is a violent storm with extreme rainfall or very strong winds. A tsunami is a huge, powerful ocean wave usually caused by an underwater earthquake or volcanic eruption.
On 26 December 2004, a massive tsunami (triggered by an earthquake near Indonesia) struck India and 13 other countries around the Indian Ocean, badly affecting the Andaman & Nicobar Islands and the coasts of Tamil Nadu and Kerala.
India has an Indian Ocean Tsunami Warning System and a National Disaster Management Authority to detect and respond to such disasters and protect lives.
4. Continents
Depending on how landmasses are grouped, the number of continents can be counted as 4, 5, 6, or 7!
| Count | Continents Listed |
|---|---|
| 4 | Africa-Eurasia, America, Antarctica, Australia |
| 5 | Africa, America, Antarctica, Australia, Eurasia |
| 6 | Africa, Antarctica, Australia, Eurasia, N. America, S. America |
| 7 (most common) | Africa, Antarctica, Asia, Australia, Europe, N. America, S. America |
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Fig 3: Relative sizes of the seven continents (Asia is the largest, Australia the smallest)
The Olympic rings symbolise the five inhabited continents โ Africa, America, Asia, Australia and Europe (Antarctica has no permanent population).
5. Islands
An island is a piece of land surrounded by water on all sides โ smaller than a continent. (Continents are technically surrounded by water too, but they're too large to be called islands.)
Greenland is the world's largest island โ as big as India's 10 largest states combined!
India has more than 1,300 islands, including two major groups: the Andaman & Nicobar Islands (Bay of Bengal) and the Lakshadweep Islands (Arabian Sea).
India has more than 1,300 islands, including two major groups: the Andaman & Nicobar Islands (Bay of Bengal) and the Lakshadweep Islands (Arabian Sea).
Since 1981, the Indian Antarctica Programme has sent scientists to research Antarctica's climate and environment โ India's first base there was Dakshin Gangotri (1983).
6. Oceans and Life
Oceans are essential to life on Earth:
โข They send rainfall to continents (including India's monsoon).
โข Ocean flora produces more than half of the world's oxygen!
โข They are part of Earth's water cycle.
โข They send rainfall to continents (including India's monsoon).
โข Ocean flora produces more than half of the world's oxygen!
โข They are part of Earth's water cycle.
๐ฏ Quick Summary
- About 71% of Earth's surface is water, ~29% is land โ Earth is nicknamed the "Blue Planet".
- There are 5 oceans (Pacific, Atlantic, Indian, Southern, Arctic) โ but they are all really one connected ocean.
- India sits between the Arabian Sea and the Bay of Bengal, both parts of the Indian Ocean.
- Oceans can cause disasters like cyclones and tsunamis (e.g. the 2004 Indian Ocean tsunami).
- Continents can be counted as 4 to 7, depending on classification; 7 is most widely used.
- An island is a small landmass surrounded by water; Greenland is the largest island in the world.
- Oceans give us rainfall, oxygen (from marine flora), and are key to the water cycle.
โ๏ธ Notes by @edugrown โ happy revising! ๐