Oceans and Continents – Class 6 Social Science Chapter 2 Notes & NCERT PDF

The Big Questions

"The ocean is everything. It covers seven-tenths of the terrestrial globe. Its breath is pure and healthy. ... The ocean is the vast reservoir of Nature." — Jules Verne (1870)

Introduction

Look at the photograph of the Earth taken from space (Fig. 2.1), centred on the Indian Ocean. Africa is to the left, India and Asia are at the top, Australia is to the right and Antarctica is at the bottom. The most widespread colour is blue, which is water. Water covers almost three-fourths of the Earth's surface, so early astronauts lovingly called the Earth the 'blue planet'. The brown patches are land, a little over one-fourth of the globe.

Did you know? The Indian Navy's motto is Śham no Varuṇah, "Be auspicious to us, O Varuna", an invocation to the Vedic deity of oceans, sky and water.

Key Concepts

1. Distribution of water and land

Maps drawn from above the North Pole and the South Pole (Fig. 2.2) show that land and water are not equally distributed. The Northern Hemisphere has more land, and the Southern Hemisphere has more water. Oceans have smaller extensions called seas, bays and gulfs.

2. The five oceans

From largest to smallest:

The lines dividing oceans are only conventions; seawater flows freely across them. Oceans are home to marine flora (algae, seaweeds) and marine fauna (fish, dolphins, whales, sea turtles, emperor penguins, coral-reef life, deep-sea creatures).

The Indian Ocean is bounded by Asia to the north, Africa to the west, Australia to the east and the Southern Ocean to the south. On either side of India are the Arabian Sea (west) and the Bay of Bengal (east).

3. Oceans and disasters

4. Continents: how many?

Continents can be counted as four to seven, depending on how we group landmasses:

Europe and Asia are one landmass. They are called two continents for historical and cultural reasons, but geologists often call them Eurasia. The five Olympic rings stand for five inhabited continents: Africa, America, Asia, Australia and Europe. The book's square diagram shows Asia as the largest and Australia as the smallest continent.

5. Islands

Islands are smaller landmasses surrounded by water on all sides. Continents are also surrounded by water but are too large to count as islands.

India in Antarctica: The Indian Antarctica Programme began in 1981. India set up its first research station, Dakshin Gangotri, in 1983 (two more came later). About 40 teams of scientists have studied the climate there, and the settlement even has a library and a post office!

6. Oceans and life

Activities in the Chapter

Key Terms

Connect to Today

The monsoon that waters Indian farms begins over the ocean. Every plastic bottle thrown away can end up choking marine life.

Common Mistakes

Questions and Activities: Hints

Q1: define continent, ocean and island in your own words, using the chapter's definitions. The crossword answers include oxygen, Greenland, continent, Asia, plastic, Antarctica, tsunami, Australia, Pacific and island.