How to do map work (and how marks are given)
In the exam you get an outline map of the world and must mark and name features. Use a pencil, a small symbol and a neat label.
- Use the equator, the Tropics (23½° N and S) and the prime meridian (0°) as guide lines.
- Colour or shade water features in blue, deserts in yellow, mountains in brown.
- Map work in this unit carries about 5 marks.
Oceans
All oceans are joined. We split them into five:
- Pacific: the largest and deepest. It has the Mariana Trench.
- Atlantic: an S-shaped ocean between the Americas and Europe–Africa.
- Indian: south of Asia; the only ocean named after a country.
- Southern: around Antarctica.
- Arctic: the smallest, around the North Pole, mostly frozen.
Major and minor plates, Ring of Fire and mid-Atlantic ridge
The outer shell of the Earth (lithosphere) is broken into big pieces called plates. They move a few cm a year.
Major plates (7)
Pacific, North American, South American, Eurasian, African, Indo-Australian, Antarctic.
Minor plates (examples)
Nazca, Cocos, Caribbean, Philippine, Arabian, Juan de Fuca, Scotia, Fuji.
Ring of Fire
A horseshoe-shaped belt around the Pacific. Plates meet here, so there are many volcanoes and earthquakes (Andes, Japan, Indonesia, New Zealand).
Mid-Atlantic ridge
A long underwater mountain chain down the middle of the Atlantic. Plates pull apart here and new crust forms. Iceland sits on top of it.
Hot deserts
Most hot deserts lie between about 15° and 30° north and south, on the west side of continents. Here dry air sinks and cold currents cool the coast, so rain is very low.
- Sahara (North Africa) — the largest hot desert
- Arabian (West Asia)
- Thar (India–Pakistan region)
- Kalahari and Namib (southern Africa)
- Atacama (South America) — one of the driest places
- Great Australian desert
- Sonoran and Mojave (North America)
Major seas
A sea is a smaller part of an ocean, partly surrounded by land.
- Arabian Sea and Bay of Bengal (Indian Ocean, next to India)
- Red Sea (between Africa and Arabia)
- Mediterranean Sea (between Europe and Africa)
- Caribbean Sea (Central America)
- South China Sea, North Sea, Black Sea
- Caspian Sea: really the world's largest lake, with salty water
Warm and cold ocean currents
Warm currents move from the equator towards the poles, usually along east coasts. Cold currents move from the poles towards the equator, usually along west coasts.
| Warm | Cold |
|---|---|
| Gulf Stream, North Atlantic Drift | Labrador, Canary |
| Kuroshio | Oyashio, California |
| Brazil | Benguela, Falkland |
| East Australian, Agulhas | Humboldt (Peru), West Australian |
Where warm and cold currents meet (e.g. Newfoundland, Japan) there are rich fishing grounds and fog.
Biodiversity hotspots
A biodiversity hotspot is a place with many plants and animals found nowhere else (endemic) that has already lost most of its natural cover. There are 36 in the world.
Four touch India: Himalaya, Western Ghats and Sri Lanka, Indo-Burma (north-east) and Sundaland (Nicobar Islands).
For marking, always use the official Government of India outline map given in the exam. Our 3D board shows only land and water, never borders.
Key formulas and definitions
- Oceans by size: Pacific > Atlantic > Indian > Southern > Arctic
- Hot deserts: 15°–30° N/S, west side of continents, next to cold currents
- Warm current → towards poles; cold current → towards equator
- Ring of Fire = belt of volcanoes and earthquakes around the Pacific
- Mid-ocean ridge = plates move apart; new sea floor forms
Worked examples
1. Why is the Atacama desert so dry even though it is next to the sea?
The cold Humboldt current cools the air above it. Cool air cannot rise to make rain clouds, and the Andes block moist winds from the east. So almost no rain falls.
2. You must mark the mid-Atlantic ridge. Where will you draw it?
Draw a wavy line from near Iceland in the north, down the middle of the Atlantic, halfway between the Americas and Europe–Africa, to the south Atlantic.
3. Name the warm and cold currents that meet near Japan and say why the area is good for fishing.
Warm Kuroshio and cold Oyashio meet there. Mixing brings nutrients up, plankton grows and fish gather, so it is a rich fishing ground.
4. Which hotspot covers the Nicobar Islands?
Sundaland, which also covers Malaysia and Indonesia's western islands.
Common mistakes
- Calling the Caspian a normal sea. It is a large salt lake with no outlet to the ocean.
- Marking hot deserts on the east side of continents. Most are on the west side, near cold currents.
- Drawing the Ring of Fire around the Atlantic. It circles the Pacific.
- Thinking warm currents flow towards the equator. Warm water flows away from the equator, towards the poles.