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Antarctica: Location, Physical Features, Climate, Natural Vegetation

ICSE Class 7 · Geography · Chapter 18

What this chapter covers

Key definitions

Antarctica is the continent that lies around the South Pole and is almost completely covered by a thick sheet of ice.

The South Pole is the southernmost point on the Earth, where all the lines of longitude meet at 90° south latitude.

The Antarctic Circle is the line of latitude at about 66½° south that marks the edge of the southern polar region.

The Southern Ocean is the ocean that surrounds Antarctica on all sides and joins the southern parts of the Atlantic, Pacific and Indian Oceans.

An ice sheet is a vast, thick layer of ice that covers a large area of land and has built up over many thousands of years.

A glacier is a large mass of ice that moves slowly downhill under its own weight.

An ice shelf is a thick, floating platform of ice that stretches out from the land over the sea while still being joined to the ice sheet.

An iceberg is a large block of freshwater ice that has broken off a glacier or an ice shelf and floats in the sea.

Sea ice is ice that forms when the surface of the sea itself freezes.

A nunatak is a mountain peak or rocky ridge that sticks out above the surface of an ice sheet.

The Antarctic Peninsula is a long, narrow arm of mountainous land that stretches from West Antarctica northwards towards South America.

An Antarctic oasis is an area of ice-free rocky land near the coast, often with small lakes of meltwater in summer.

Key points

Questions answered

Why does Antarctica have no land boundary with any other continent?
Antarctica is surrounded on all sides by the Southern Ocean, so water separates it from every other continent. The nearest continent, South America, lies about 1,000 km away across the Drake Passage.
Name the mountain range that divides Antarctica into East and West Antarctica, and give one difference between the two parts.
The Transantarctic Mountains divide the continent. East Antarctica is larger and higher, with ice resting on old, solid rock, while West Antarctica is smaller and lower, with much of its ice resting on rock below sea level.
What is the difference between an ice shelf and sea ice?
An ice shelf is a thick, floating platform of land ice that is still joined to the ice sheet. Sea ice forms when the surface of the sea itself freezes.
Give three reasons why Antarctica is the coldest continent.
It lies around the South Pole, so the Sun's rays are very slanting; its white ice reflects most of the sunlight; and much of it stands 2,000–3,000 m above sea level, where the air is thin and cold. Its isolation by the cold Southern Ocean also helps to keep it cold.
Antarctica is covered in ice, yet it is called a desert. Explain why.
A desert is a place that receives very little precipitation. The interior of Antarctica receives less than 50 mm of snow, measured as water, in a year, because the cold air holds very little water vapour. The ice has built up only because the snow almost never melts.
At a coastal station, the average temperature is −5 °C in the warmest month and −30 °C in the coldest month. What is the annual range of temperature there?
The annual range is the warmest month minus the coldest month: -5 - (-30) = -5 + 30 = 25 \circC.
Why does Antarctica have no forests or grasslands? Name two kinds of plants that do grow there.
The land is buried under ice or is bare, frozen rock with almost no soil, and the summer is too short and cold for trees or grasses. Mosses and lichens grow there, along with algae and two small flowering plants on the Antarctic Peninsula.
Why are krill important to the wildlife of Antarctica?
Krill are eaten by fish, squid, penguins, seals and whales, so almost every Antarctic animal depends on them, directly or through the animals it eats.