Hinglish

Oceans

Class 6 Social Science · Chapter 2: Oceans and Continents · NCERT Exploring Society: India and Beyond section 2.2

Learn

There are five oceans, all joined together into one great world ocean: the Pacific (largest and deepest), the Atlantic, the Indian, the Southern (around Antarctica) and the Arctic (smallest, around the North Pole, mostly frozen). The Indian Ocean is the only ocean named after a country.

Ocean water is always moving. Waves are made by wind blowing over the surface. Tides are the daily rise and fall of the sea, caused mainly by the pull of the Moon. Ocean currents are like huge rivers inside the ocean, carrying warm or cold water across the world.

Oceans and disasters: a tsunami is a giant wave set off by an undersea earthquake. In 2004, a tsunami struck the coasts of the Indian Ocean, including Tamil Nadu and the Andaman and Nicobar Islands. Cyclones form over warm seas like the Bay of Bengal and bring strong winds and heavy rain to the coast.

Today, satellites and warning centres track earthquakes and cyclones, so people living on the coast can be warned in time and moved to safe shelters. Mangrove forests along the coast also act like a shield against big waves.

Explore: biggest to smallest.

  1. Put the five oceans in order, largest first.

Remember

  • Five connected oceans: Pacific, Atlantic, Indian, Southern, Arctic; the Pacific is the largest.
  • Waves, tides and currents move ocean water; tsunamis and cyclones are ocean disasters.

Quick check

What mainly causes tides?

  1. The pull of the Moon
  2. Fish swimming
  3. Ships
  4. Rain
Answer

The pull of the Moon. The Moon's gravity pulls on the oceans.

Think about it

Why do you think mangrove forests are now protected along many coasts?

One answer

Their thick roots slow down waves and storm surges, hold the soil, and give shelter to fish and birds. Coasts with mangroves suffered less damage in the 2004 tsunami.

Practice

Practise with fresh questions at three levels (easy, medium, hard), some answered hands-on, with hints and worked answers. Get 4 of your last 5 right to finish the topic.