Class 8 Social Science Chapter 8: World Geography: Some Glimpses
- 4 topics
- 100 MCQs
- 28 short answers
- 12 long answers
- 68 flashcards
- 20 games
- ~154 min read
- English
Mapping the Earth
An orange that will not lie flat, two projections that each give something up, a Greenland smaller than India, and a colour language that lets a map be read without its key.
What you will be able to do
- Explain why every flat map of the Earth distorts something.
- Define a map projection and say why it is a method rather than a style.
- Compare the Mercator and Robinson projections and their costs.
- Read a physical map from its colour language alone.
- Explain why professionals use coordinates where precision matters.
Key points
The Earth is an oblate spheroid: nearly spherical, bulging at the middle and pressed in at top and bottom because it spins.
A curved surface cannot be laid flat without tearing or gaps, as an orange peel shows, so every flat map carries distortion.
Drawing the curved Earth onto flat paper is what a projection does, which is a method with a stated cost rather than a drawing style.
Some maps keep shapes and distort sizes; others keep sizes and bend shapes, and no map can keep both.
Mercator preserves shape and direction, which suits navigation, and distorts size badly near the poles.
On Mercator, Greenland looks as large as Africa and larger than India, though it is in fact smaller than India.
Robinson balances the two distortions, so neither is exact and neither badly wrong, which is why it looks realistic.
Every map being a compromise, the chapter advises comparing several projections, and professionals use latitude and longitude instead.
The colour language runs blue for water, green for plains, yellow and brown for plateaus, dark brown for high mountains, light yellow for deserts and white for ice.
Full explanation
A map is not a photograph
Before looking at the world's landforms, it is worth knowing what a world map can and cannot tell you. This chapter deals with physical maps, which show natural features rather than borders, and they turn out to be arguments rather than pictures.
The shape being drawn
The Earth is an oblate spheroid. That means it is nearly spherical, but it swells around the middle and is pressed in at top and bottom, because it spins. So the surface being mapped curves in every direction at once.
Try it with an orange
Take an orange and imagine it is the Earth. Peel it, and then try to lay the peel out flat without tearing anything. It cannot be done. Either the peel splits or gaps open between the pieces, and there is no way to avoid both.
Which is why maps lie
That is the whole reason every world map carries some distortion. Turning a curved surface into a flat one is called a map projection, and a projection is not a drawing style. It is a method, and every method has a price.
The people who do it
A cartographer is somebody who draws or produces maps. Cartographers have tried many ways of representing the Earth accurately, using different methods of laying the world out flat. None of the attempts escapes the problem; they only choose where to put the error.
The two kinds of error
Some maps give the right shapes for countries and the wrong sizes. Others give the right sizes and bend the shapes. You can keep one or the other, and the arithmetic of a curved surface will not let you keep both.
The Mercator projection
Mercator keeps shapes and directions correct, which makes it genuinely useful for navigation: a straight line on it is a usable bearing. The cost falls on size, and it falls hardest near the poles.
What that looks like
On a Mercator map Greenland appears about as large as Africa, and larger than India. In fact Greenland is smaller than India. That is not a mistake in the map; it is the price the map announced in advance.
The Robinson projection
Robinson is a compromise. It balances the distortion of size against the distortion of shape, so neither is exactly right and neither is badly wrong. The result looks more like what people expect the world to be, which is why it is often described as a realistic world map.
Every map is a compromise
That sentence is the heart of the topic. There is no correct world map waiting to be drawn. To understand the world fairly, the chapter advises looking at several projections rather than trusting any single one.
What flat maps are good for
They give a visual representation, letting you judge how big a thing is, what shape it has, where it sits and how far off at a glance. For most purposes that is exactly what is wanted, and it is why they are printed in books.
And what professionals use instead
Where precision matters, people work with latitude and longitude coordinates, which were introduced in Grade 6. Coordinates do not care how the page is laid out, so the distortion of the drawing does not enter the calculation.
The colour language
A physical map has a language of colours, and knowing it lets you read one without a key. Blue marks water bodies: oceans, seas, lakes and rivers. Green marks plains.
The browns and yellows
Yellow and brown mark plateaus. Dark brown marks high mountains, so a darkening across a map is land rising. Light yellow marks deserts, and the distinction between light yellow and the browns is worth attention, because one is dry and the other is high.
The fifth colour
White marks ice and glaciers. On a world map that puts white at both ends and across the high mountain chains, which is a useful check: white in the middle of a continent usually means altitude rather than latitude.
Reading a map as a claim
Put the two halves of this topic together and a physical map becomes readable in a different way. The colours tell you what is there. The projection tells you how much to trust the size and shape of it. A reader who holds both is in a position to be properly sceptical.
Why this comes first
The rest of the chapter tours the continents using maps like these. Knowing that Greenland is not the size of Africa, and that a brown patch is high rather than dry, is what makes the tour mean anything at all.
Concepts and terms
A nearly spherical shape that swells around the middle and is pressed in at top and bottom because of its rotation. It is the shape a world map has to represent.
The business of turning a round Earth into a flat drawing. It is a method with a cost rather than a style, and it decides which kind of accuracy the finished map keeps.
A person who draws or produces maps. Cartographers have tried many methods of laying the world out flat, and none of them escapes distortion.
A projection preserving shape and direction, which makes it useful for navigation, at the cost of badly distorting size near the poles.
A compromise projection balancing the distortion of size against that of shape, so that neither is exactly right and neither is badly wrong.
Traps to avoid
Common misconceptions
Two maps of one world
Scenario:
A class is given two world maps side by side. On the first, Greenland looks about the size of Africa and the shapes of coastlines are exact. A sailor could set a course from it. On the second, nothing is exactly right, but nothing is badly wrong either, and the proportions of the continents look believable. A student asks which of the two is the correct map. Their teacher answers that the question cannot be settled, and asks instead what each map is for.
Analysis:
A map is an argument about what matters, not a photograph. The useful question is never which map is right but what each one was built to do.
Activity:
Find a third projection and work out what it gives up.
Flatten a peel
Title:
Flatten a peel
Safety:
An adult should handle the knife.
What You Notice:
The peel either tears or leaves gaps, and both are the same problem every map projection has to solve.
Did you know
Greenland is smaller than India, although a Mercator map draws it larger than India and roughly the size of Africa.
No world map can be made free of distortion, which is why an orange peel cannot be laid flat without tearing or leaving gaps.
A physical map can be read without its key, because the colours are a fixed language rather than a choice each mapmaker makes afresh.
Memory tricks
The colour language — BLUE WET, GREEN FLAT, BROWN HIGH, WHITE COLD — Water, plains, plateaus and mountains, then ice, with light yellow kept for dry rather than high.
The two projections — MERCATOR SAILS, ROBINSON LOOKS RIGHT — One keeps bearings true for navigation; the other balances the errors so the world looks as expected.
Practice MCQs with answers (25)
- A borders between countries rather than natural features
- B natural features rather than borders between countries
- C only the oceans and the seas of the world
- D only those features that people have built
Show answer
Why:
Which is what a geography chapter needs.
- A a flattened disc with a raised rim at the edge
- B a perfect sphere of even radius throughout
- C an oblate spheroid, bulging at the equator
- D an egg shape, pointed at the northern pole
Show answer
Why:
And pressed in at top and bottom.
- A the Moon's pull has stretched it towards one pole
- B the weight of the oceans pulls the middle in
- C mountains on one side outweigh the other side
- D its rotation makes it bulge at the equator
Show answer
Why:
And flattens it a little at the poles.
- A fruit skin behaves differently from the Earth's crust
- B a curved surface cannot be flattened without damage
- C maps are easier to draw on a curved surface
- D the Earth's surface is smaller than it appears
Show answer
Why:
It tears, or gaps open, and both are unavoidable.
- A the scale printed in the corner of every finished map
- B the style in which a cartographer chooses to draw
- C the business of drawing the curved Earth onto flat paper
- D the particular set of colours used to mark different landforms
Show answer
Why:
A method with a cost, not a decoration.
- A names newly discovered landforms
- B studies the Earth's interior structure
- C measures the depth of the oceans
- D draws or produces the maps themselves
Show answer
Why:
Many have tried to map the Earth accurately.
- A right shapes with wrong sizes, or right sizes with bent shapes
- B right colours with wrong labels, or right labels with no colour
- C right distances with wrong directions, or neither of the two
- D right borders with wrong features, or right features only
Show answer
Why:
A curved surface will not permit both to be right.
- A preserves the true size of every landmass
- B preserves shape and direction across the map
- C shows the shortest route between two ports
- D marks the ocean currents along each coast
Show answer
Why:
A straight line on it is a usable bearing.
- A along the prime meridian
- B near the equator
- C near the poles
- D across the Pacific
Show answer
Why:
Which is why Greenland looks enormous.
- A Both true, and the reason explains the assertion
- B Both true, but the reason does not explain it
- C The assertion is true and the reason is false
- D The assertion is false and the reason is true
Show answer
Why:
Both are correct, and the second explains the first: a projection states its cost, so paying that cost is not a mistake.
- A about the same in size as India
- B larger than India but smaller than Africa
- C about the same in size as Africa
- D smaller than India happens to be
Show answer
Why:
Mercator makes it look much larger than it is.
- A balances the distortion of size against that of shape
- B removes all distortion from the middle of the map
- C shows only those continents that fit without error
- D uses two separate scales on the same sheet
Show answer
Why:
Neither is exact and neither badly wrong.
- A using only the projection that looks most realistic
- B looking at several projections rather than one
- C avoiding flat maps and using globes alone
- D treating the Mercator map as the standard
Show answer
Why:
Because every map is a compromise.
- A I and II only, since precision calls for coordinates
- B I and III only, since some projections are exact
- C II and III only, since they show nothing reliably
- D I, II and III are all correct as stated above
Show answer
Why:
Latitude and longitude are used instead.
- A they are printed at a larger scale than any map
- B they are measured by satellite rather than by hand
- C they do not depend on how the page was laid out
- D they describe only places near the equator
Show answer
Why:
So the drawing's distortion never enters it.
- A the borders agreed between any two countries
- B the coldest regions, whatever their altitude
- C land lying below the level of the open sea
- D water bodies: oceans, seas, lakes and rivers
Show answer
Why:
The colour language works without a key.
- A green
- B dark brown
- C light yellow
- D white
Show answer
Why:
Browns and yellows are kept for higher ground.
- A deep ocean trenches
- B high mountains
- C hot deserts
- D dense forest
Show answer
Why:
So a darkening is land rising.
- A light yellow means cold, while brown means warm
- B light yellow means high, while brown means dry
- C light yellow means dry, while brown means high
- D light yellow means forested, while brown means bare
Show answer
Why:
Deserts against plateaus, which is easy to confuse.
- A political capitals
- B salt flats
- C unmapped territory
- D ice and glaciers
Show answer
Why:
Ice sits on altitude as well as on latitude.
- A altitude rather than latitude
- B latitude rather than altitude
- C an area nobody has surveyed
- D a lake too small to colour blue
Show answer
Why:
Ice can sit high as well as far north or south.
- A green with plateaus, and dark brown with plains
- B green with plains, and dark brown with high mountains
- C blue with glaciers, and white with rivers
- D light yellow with mountains, and brown with deserts
Show answer
Why:
Height rises as the colour darkens.
- A the scale of the map, and the date it was printed
- B the names of the continents, and their populations
- C what the colours show, and how far to trust the shapes
- D the borders of countries, and the capitals inside them
Show answer
Why:
Colours report; the projection sets the doubt.
- A the colours differ from one continent to another
- B the continents are named in alphabetical order after it
- C projections were invented before the continents were mapped
- D the tour uses maps, which have to be read properly first
Show answer
Why:
Knowing brown is high is what makes the tour work.
- A every flat map of the world is a compromise with a cost
- B modern maps have removed the distortions of older ones
- C a physical map needs no key once the scale is known
- D the Earth's shape makes accurate mapping straightforward
Show answer
Why:
Which is why several should be compared.
Important short questions (7)
A nearly spherical shape that swells around the middle and is pressed in at top and bottom. The Earth is one because it spins.
That a curved surface cannot be laid flat without tearing or leaving gaps. Every flat map of the Earth must distort something.
The business of turning a round Earth into a flat drawing. It is a method with a stated cost, which decides what the map can report truly.
It preserves shape and direction, which makes it useful for navigation. It sacrifices size, most severely near the poles.
On a Mercator map Greenland looks about as large as Africa and larger than India, though it is in fact smaller than India. The distortion is the map's announced price.
Because every map is a compromise, so no single one is correct. Each projection reveals what another conceals.
Blue for water bodies, green for plains, yellow and brown for plateaus, dark brown for high mountains. Light yellow is for deserts, and white for ice and glaciers.
Long answer questions (3)
The Earth is an oblate spheroid, nearly spherical but bulging at the equator and flattened a little at the poles. Its surface therefore curves in every direction. Peel an orange and try to lay the peel flat, and it either tears or leaves gaps between the pieces. Neither can be avoided. Drawing the curved Earth onto flat paper calls for a map projection, and every projection has to put the error somewhere. Some maps give right shapes with wrong sizes and others give right sizes with bent shapes, so every map is a compromise.
Mercator keeps shape and direction correct. That makes it genuinely useful for navigation, since a straight line on it is a usable bearing. The cost falls on size, and hardest near the poles. Greenland appears about as large as Africa and larger than India, though it is in fact smaller than India. Robinson is a compromise instead. It balances the distortion of size against that of shape. Neither is exactly right and neither badly wrong, which is why it looks realistic.
Read the colours first, because they are a fixed language. Blue is water, green is plains, yellow and brown are plateaus, dark brown is high mountains, light yellow is desert and white is ice and glaciers. A darkening colour therefore means rising land, and white inland usually means altitude rather than latitude. Then hold the projection in mind, because it decides how far the sizes and shapes can be trusted. It matters because the rest of the chapter tours the continents on maps like these, and misreading one misreads the tour.
Flashcards (17)
Play this topic
- Match each colour to what it marks
- Mercator, Robinson, or neither?
- Fact or myth
- Put the orange experiment in order
- Match each term to its meaning
The Oceans
Most of the planet's surface and nearly all its water, a current that warms Britain from the equator, and a snail feeding in total darkness.
What you will be able to do
- State what share of the Earth's surface and water the oceans account for.
- Explain the three things the oceans do, including how they steady climate.
- Distinguish the five oceans by their characteristic features.
- Explain what an ocean current is and what the Gulf Stream demonstrates.
- Describe the Mariana Trench and explain how a food chain works without light.
Key points
Salt water covers roughly 71 per cent of the planet's surface, which is why it reads as the blue planet from space.
The oceans hold about 97 per cent of all the Earth's water, so rivers, lakes and ice share the remaining three.
They support life from plankton to blue whales, absorb heat and release it slowly, and add moisture to the air for cloud and rain.
The ocean floor carries its own ranges, troughs and flats, together with deep V-shaped trenches.
The five oceans are the Indian, Pacific, Arctic, Atlantic and Southern, and each has a distinct character.
A current is like a giant river in the sea: warm ones run poleward, cold ones run towards the equator.
The Gulf Stream leaves the United Kingdom milder than other places at the same latitude, so latitude alone does not fix climate.
The Mariana Trench beats Everest's height by more than two kilometres, running tall, and the Challenger Deep passes 11,000 metres down.
Where no light reaches, bacteria make food from chemicals in the water and animals feed on them, so a food chain needs energy rather than sunlight.
Full explanation
Why the planet looks blue
An ocean is a huge body of salt water, and together the oceans cover something like 71 per cent of the Earth's surface. That is why the planet reads as blue from orbit, and why the first astronauts to see it called it the blue planet.
Where the water is
The oceans hold about 97 per cent of all the water on Earth. Everything else, the rivers and lakes and groundwater and ice that life on land depends on, comes out of the remaining three per cent.
Three things the oceans do
They carry life, from plankton small enough to need a microscope up to blue whales. They absorb heat and let it out again slowly. And they put moisture into the air, which becomes cloud and then rainfall.
Why that middle one matters
Absorbing heat and releasing it slowly is what regulates climate. Water takes a great deal of warming to change temperature, so a planet with oceans swings between hot and cold far less than one without them would.
The floor is not flat
It is easy to picture the sea bed as a smooth basin, because water hides it and a map of the surface shows nothing. In fact it carries mountains, troughs and flats, exactly as dry land does.
Five oceans
Grade 6 introduced them: the Pacific, the Atlantic, the Indian, the Southern and the Arctic. Each has a character of its own, and the characters are worth holding because they explain a good deal about trade, weather and wildlife.
The Arctic and the Southern
The Arctic is the smallest and the shallowest, covered with sea ice, and home to polar bears and walruses. The Southern encircles Antarctica, and penguins and seals belong to it.
The Pacific, the Atlantic, the Indian
The Pacific is the largest and the deepest, with whales and tuna in it. The Atlantic is among the busiest waterways for trade and transport, and a rich fishing ground. The Indian has warm waters and a rich variety of life, and it has mattered to international trade for a very long time.
Currents
The oceans are never still. A current is best pictured as a giant river running through the sea. Warm currents carry warm water away from the equator towards the poles. Cold currents carry cold water from the poles back towards the equator.
What a current can do to a country
The Gulf Stream starts in the warm water of the tropics and runs north through the Atlantic towards western Europe. The warmth it brings leaves the United Kingdom milder than other places lying at the same latitude.
Which overturns a rule of thumb
That one example breaks a tempting assumption, that places at the same distance from the equator share a climate. Latitude is one factor among several, and a current can outweigh it.
Trenches
The sea floor has very deep, V-shaped valleys called trenches. They are the deepest places on the planet, and the deepest of all of them is the Mariana Trench.
How deep that is
Everest, stood on the floor of the trench, would still have two kilometres of water above it. Its lowest point, called the Challenger Deep, lies past 11,000 metres beneath the surface of the sea. Put the mountain in the trench and its summit would still be well under water.
What it is like down there
Temperatures near freezing, pressure that would crush most things, and total darkness. The chapter calls it one of the harshest environments anywhere on Earth, and that is not an exaggeration.
And yet
Scientists studying these trenches keep finding life forms that exist nowhere else. A snail has been photographed on the floor of the Mariana Trench, feeding.
How anything eats without light
Where no light arrives, nothing can use sunlight to make food. So the organisms there use energy from chemicals dissolved in the water instead. Bacteria build food that way, and animals such as the snail feed on the bacteria.
What that tells you about life
A food chain needs an energy source, and it does not have to be the Sun. Where light cannot reach, chemistry does the same job and a whole community stands on top of it. Life finds ways to survive, and even to thrive, in conditions that look impossible for it.
Why any of this is in a geography chapter
Because the ocean turns out not to be a still container with fish in it. It moves heat from one hemisphere towards another. It decides how mild a country is, regardless of where that country sits. And it holds whole systems of life in places no light has ever reached. A geography of the Earth that left the sea out would be a geography of less than a third of it.
Concepts and terms
A huge body of salt water. Together the oceans cover roughly 71 per cent of the planet's surface and hold about 97 per cent of its water.
The oceans absorb heat and release it slowly, which works because water changes temperature only slowly. A planet with oceans swings between hot and cold far less.
A flow of water like a giant river running through the sea. Warm currents carry water from the equator towards the poles, and cold currents the other way.
A very deep, V-shaped valley in the sea floor, and the deepest kind of place on the planet. The Mariana is the deepest of them.
Where no light reaches, bacteria take energy from chemicals dissolved in the water to build food, and animals feed on those bacteria. Energy is needed; sunlight is not.
Traps to avoid
Common misconceptions
A snail with no sunlight
Scenario:
A photograph taken on the floor of the Mariana Trench shows a snail. Nothing about the place suits life. The temperature is near freezing and the pressure is crushing. No light has ever reached that depth, so no plant there can use sunlight to make food. Yet the snail is feeding, and what it feeds on are bacteria that build their own food out of chemicals dissolved in the water. Scientists studying such trenches keep finding life forms that exist nowhere else on the planet.
Analysis:
A food chain needs an energy source, not necessarily the Sun. Where light cannot reach, chemistry does the same job, and the whole community above it follows.
Activity:
Find out what else has been photographed in a deep trench, and what it eats.
Measure the trench against a mountain
Title:
Measure the trench against a mountain
Safety:
Drawing only.
What You Notice:
The deep is further from sea level than the summit, which is why the chapter puts the two numbers side by side.
Did you know
The Mariana Trench is Deeper than Everest is tall, by more than two kilometres, so sinking the mountain into it would leave the summit well under water.
A snail has been photographed on the floor of the Mariana Trench, feeding on bacteria that build their own food out of chemicals in the water.
The United Kingdom is milder than other places at the same latitude because the Gulf Stream carries warm water north to it from near the equator.
Memory tricks
The two percentages — SEVENTY-ONE ACROSS, NINETY-SEVEN WITHIN — 71 per cent of the surface is covered; 97 per cent of the water is held.
The direction of currents — WARM OUT, COLD BACK — Warm water travels out from the equator to the poles; cold water travels back from the poles to the equator.
Practice MCQs with answers (25)
- A 51 per cent
- B 97 per cent
- C 71 per cent
- D 29 per cent
Show answer
Why:
Which is why it is called the blue planet.
- A 29 per cent
- B 71 per cent
- C 50 per cent
- D 97 per cent
Show answer
Why:
Everything else comes out of the other three.
- A 71 is the surface covered; 97 is the water held
- B 97 is the surface covered; 71 is the water held
- C both refer to the surface, in different years
- D both refer to the water, measured two ways
Show answer
Why:
Surface area and water volume are different claims.
- A supporting life from plankton to whales
- B generating the Earth's magnetic field
- C absorbing heat and releasing it slowly
- D adding moisture to the air for rainfall
Show answer
Why:
Three jobs are listed, and that is not one.
- A the salt in seawater prevents it from freezing
- B water reflects almost all the sunlight that reaches it
- C water needs much heat to change temperature at all
- D the oceans are deeper than the atmosphere is tall
Show answer
Why:
So it absorbs warmth and releases it slowly.
- A has never been mapped at any point
- B is a smooth basin sloping gently from the coast
- C is flat except where rivers have cut into it
- D carries its own ranges, troughs and flats
Show answer
Why:
And V-shaped trenches as well.
- A the Arctic
- B the Southern
- C the Indian
- D the Atlantic
Show answer
Why:
Ice-covered, with polar bears and walruses.
- A the Atlantic
- B the Pacific
- C the Indian
- D the Southern
Show answer
Why:
It is the largest and the deepest of the five.
- A the Arctic, encircling Antarctica
- B the Southern, the shallowest of the five
- C the Southern, encircling Antarctica
- D the Indian, the largest of the five
Show answer
Why:
Penguins and seals belong to the Southern.
- A Both true, and the reason explains the assertion
- B Both true, but the reason does not explain it
- C The assertion is true and the reason is false
- D The assertion is false and the reason is true
Show answer
Why:
Both are correct, but the share of the world's water does not explain the difference in climate. A current carrying warm water far from the equator does.
- A a whirlpool fixed in one position
- B a wave travelling across the surface
- C a tide that rises and falls each day
- D a giant river running through the sea
Show answer
Why:
Warm ones move poleward, cold ones equatorward.
- A from the equator towards the poles
- B from the poles towards the equator
- C from the surface down to the sea floor
- D from one ocean trench into another
Show answer
Why:
Which is what a warm current does.
- A south through the Atlantic Ocean towards Antarctica
- B north through the Atlantic towards western Europe
- C east across the Pacific towards South America
- D west through the Indian Ocean towards Africa
Show answer
Why:
Starting near the equator, where water is warm.
- A wetter but no warmer than its neighbours
- B colder than other places at the same latitude
- C milder than other places at the same latitude
- D unaffected, since currents move too slowly
Show answer
Why:
Which is why latitude alone will not do.
- A a channel cut through land to join two seas
- B a long ridge rising towards the sea surface
- C a flat plain stretching out from a coastline
- D a very deep, V-shaped valley in the sea floor
Show answer
Why:
The deepest places anywhere on the planet.
- A the trench beats the mountain's height by over two kilometres
- B the peak is over 2,000 metres higher than the trench is deep
- C the two are within a hundred metres of each other
- D the comparison cannot be made, as they use different scales
Show answer
Why:
Sink the mountain and its summit stays under water.
- A the Mariana Abyss
- B the Challenger Deep
- C the Pacific Trough
- D the Everest Deep
Show answer
Why:
It lies over 11,000 metres below sea level.
- A I, II and III are all correct as stated above
- B I and II only, since some light does reach it
- C II and III only, since the water there is warm
- D III only, since pressure falls with depth
Show answer
Why:
One of the harshest environments on Earth.
- A the pressure crushes any plant that grows there
- B the water is too salty for any plant to grow
- C no light arrives, so sunlight cannot be used
- D there are no minerals dissolved in the water
Show answer
Why:
So chemistry supplies the energy instead.
- A nutrients carried down by ocean currents
- B faint sunlight filtering down from the surface
- C heat rising from the Earth's molten interior
- D energy from chemicals dissolved in the water
Show answer
Why:
And animals such as the snail feed on them.
- A bacteria that make their own food from chemicals
- B plankton that has sunk down from the surface above
- C plants growing in the sediment of the trench
- D minerals it filters directly out of the water
Show answer
Why:
Which is how the food chain there begins.
- A they always begin with a plant of some kind
- B they need an energy source, not necessarily the Sun
- C they cannot exist below a certain depth of water
- D they require light at some stage of the process
Show answer
Why:
Where light fails, chemistry does the same job.
- A early maps of the sea bed were drawn without detail
- B most of it really is flat, apart from the trenches
- C water hides it and a surface map shows nothing of it
- D sediment has filled in the valleys over time
Show answer
Why:
The picture is a gap in evidence, not a fact.
- A the Pacific
- B the Arctic
- C the Southern
- D the Indian
Show answer
Why:
Warm waters, rich biodiversity, and old trade.
- A the ocean is an active system, not a still container
- B the ocean is far too large for anybody to study it
- C the ocean has no effect at all on life on the land
- D the ocean is the same temperature all the way through
Show answer
Why:
It moves heat, and it holds life where none seems possible.
Important short questions (7)
About 71 per cent is the share of the Earth's surface they cover. About 97 per cent is the share of the Earth's water they hold.
They support life, regulate climate, and add moisture to the air. They regulate climate by absorbing heat and releasing it slowly, because water changes temperature only slowly.
Because it carries ranges, troughs and flats just as the land does, along with deep V-shaped trenches. Water hides all of it from view.
A flow like a giant river running through the sea. Warm currents carry warm water from the equator poleward; cold currents carry cold water back towards the equator.
It carries warm water north through the Atlantic to western Europe, leaving the United Kingdom milder than places at the same latitude. Latitude alone does not fix climate.
Deeper than Everest is tall by over two kilometres. Its deepest point, the Challenger Deep, lies more than 11,000 metres below sea level.
Bacteria use energy from chemicals dissolved in the water to make food. Animals such as the trench snail feed on those bacteria.
Long answer questions (3)
Salt water covers roughly 71 per cent of the planet's surface. The oceans hold about 97 per cent of its water. Almost everything wet on the planet is therefore in them. They support life across an enormous range, from plankton that need a microscope up to blue whales. They regulate climate by absorbing heat and letting it out slowly. That works because water changes temperature only slowly. And they add moisture to the air, which forms cloud and then rain, so the water falling on land began in the sea.
The oceans are never still. A current is best pictured as a giant river running through the sea. Warm currents carry warm water away from the equator towards the poles, and cold currents carry cold water from the poles back towards the equator. The Gulf Stream begins near the equator and runs north through the Atlantic towards western Europe, and the warmth it brings leaves the United Kingdom milder than other places at the same latitude. That overturns a tempting rule of thumb: latitude is one factor among several, not the only one.
Trenches are very deep, V-shaped valleys in the sea floor, and the Mariana is the deepest of them. It runs Deeper than Everest is tall, by more than two kilometres, and the Challenger Deep within it passes 11,000 metres below sea level. Temperatures near freezing, crushing pressure and unbroken dark leave it among the least liveable places on Earth. Even so, scientists keep finding life there. With no light, bacteria build food from chemicals dissolved in the water, and animals such as a photographed snail feed on those bacteria.
Flashcards (17)
Play this topic
- Match each ocean to what marks it out
- Fact or myth
- Surface, water, or depth?
- Build the trench food chain
- Match each figure to what it describes
Reefs and the Naming of Waters
An animal that builds a ridge holding a quarter of ocean life, the difference between a gulf and a bay, and a cut that removed a voyage round Africa.
What you will be able to do
- Define a reef and explain what corals actually are.
- Explain why reefs matter out of proportion to their area, and what threatens them.
- Distinguish a sea, a gulf, a bay, a strait and a canal with examples.
- Explain why ports sit in bays rather than on open coasts.
- Explain what the Suez Canal changed and why that case is striking.
Key points
A reef is a ridge at or near the sea surface, natural or made by people, and a natural one may be rock or built by corals.
Corals are tiny sea animals, not plants or rocks, and a coral reef is their construction.
Reefs are among the most diverse ecosystems on Earth and shelter about a quarter of all ocean species in a tiny share of its area.
Overfishing, pollution and climate change threaten reefs, and bleaching follows chemical change in the water largely caused by people.
The Great Barrier Reef lies off north-eastern Australia, runs over 2,000 kilometres, covers some 350,000 square kilometres and is a World Heritage Site.
A sea is partly enclosed and joined to an ocean, a gulf cuts deeply into land, and a bay is a smaller and broader inlet.
A strait is a narrow natural channel between seas, while a canal is cut by people to connect water bodies.
Ports sit in bays because the surrounding land shelters a harbour from the strong winds of the open ocean.
The Suez Canal, opened in 1869 between the Red Sea and the Mediterranean, removed the voyage round Africa from the India-to-Europe route.
Full explanation
What a reef is
A reef is a ridge lying at or just below the surface of the sea. Some are natural and some have been made by people. A natural one may be a ridge of rock, or it may have been built by corals.
Corals are animals
That is the detail most often got wrong. A reef looks like stone and branches like a shrub, but corals are tiny sea animals, and a coral reef is something they have constructed over a very long time.
The rainforests of the sea
Reefs are among the most diverse ecosystems anywhere on Earth, which is why they are often given that nickname. They provide food and shelter for roughly a quarter of everything living in the sea: fish and crabs, turtles and sponges.
Why a quarter is the striking figure
Reefs occupy a tiny fraction of the sea's area. Holding a quarter of its species in that fraction is what makes losing one so costly: the loss is not proportional to the space.
What threatens them
Human activity, chiefly. Overfishing removes the animals the system depends on. Pollution changes the water. And climate change warms it. The chapter calls their conservation crucial, and those three are the reasons.
Bleaching
When coral bleaches it loses its colour and then dies, and the home of a great many sea creatures goes with it. Bleaching follows changes in the chemical make-up of ocean water, and those changes are largely caused by what people do.
The Great Barrier Reef
It lies off the north-eastern coast of Australia. It runs for more than 2,000 kilometres and covers something like 350,000 square kilometres, which makes it visible from space.
The life the reef holds
It is a complex, interconnected habitat holding hundreds of species of coral and fish and other sea creatures running into thousands of species. It has been recognised as a UNESCO World Heritage Site, and the chapter calls it one of the planet's most remarkable features.
Why the waters have names
Away from the open ocean, the sea takes different shapes where it meets land, and those shapes are classified and named. The system is not a whim: each name describes a different relationship between water and coast.
Sea, gulf and bay
A sea is a large, partly enclosed area of salt water joined to an ocean, as the Arabian Sea is. A gulf is a large inlet cutting deeply into the land, like the Persian Gulf. A bay is a smaller and broader inlet, like the Bay of Bengal.
The one to watch
Gulf and bay are the pair people confuse. The difference is how the water meets the land: a gulf cuts in deeply and narrowly, a bay opens broadly and less far. Both are inlets; the shape is the distinction.
Strait and canal
A strait is a narrow channel joining two seas or oceans, like the Strait of Malacca. A canal is a channel people have made to connect water bodies, like the Suez Canal. One is natural and one is cut.
What these shapes are for
They matter for trade and travel. Take the Persian Gulf, which has carried trade between India and Europe for thousands of years, and that is a fact about its shape before it is a fact about its history.
Why ports sit in bays
A bay gives shelter. The land curving around it shields a harbour from the strong winds of the open ocean, so ships can load and unload in conditions that would be dangerous outside. That is why ports and dockyards cluster in them.
The largest bay in the world
The Bay of Bengal holds that title. It has mattered to trade, it influences the climate around it, and it is home to a wide variety of plants and animals.
The Suez Canal
It opened in 1869, a passage made by people joining the Red Sea to the Mediterranean. The effect was to create a route from the Indian Ocean through to Europe, and it remains the shortest sea route from India to Europe.
Why a strait is worth naming
A strait is narrow, and that is the whole of its importance. Traffic between two seas has to pass through it, so whoever sits beside one sits beside everything that goes by. Malacca is the example the chapter gives.
What a canal actually buys
Before it existed, a ship from Mumbai to London had to go round Africa. The canal removed that whole detour. A cut a few tens of kilometres long shortened a journey by thousands, which is the clearest case in the chapter of geography being altered rather than merely used.
Concepts and terms
A ridge standing at the sea's surface or just beneath it, thrown up naturally or by people. A natural reef may be a ridge of rock, or may have been built by corals over a long time.
A tiny sea animal. A coral reef is a structure those animals have built, which is why a reef that looks like rock is in fact alive.
The loss of colour and then the death of coral, following changes in the chemical make-up of ocean water that are largely caused by human actions.
Both are inlets of the sea. A gulf is large and cuts deeply into the land; a bay is smaller and broader and reaches in less far.
A strait is a narrow natural channel joining two seas or oceans. A canal is a channel cut by people to connect water bodies, such as the Suez.
Traps to avoid
Common misconceptions
Why the bays hold the ports
Scenario:
A class is given a map of the Indian coast and asked to mark where they would build a harbour. Most of them choose places where the coastline curves inward. Their teacher asks why nobody picked the open coast facing the ocean directly. The answer turns out to be the weather. A bay is a broad inlet, and the land around it blocks the strong winds that come in off open water. Ships in a bay can load and unload in conditions that would be dangerous outside it. The Bay of Bengal is the largest bay in the world.
Analysis:
Geography sets the terms that history then works within: the shape of a coast decides where trade can physically happen, long before anybody chooses to trade there.
Activity:
Find the nearest major port to you and look at the shape of its coastline.
Classify five waters
Title:
Classify five waters
Safety:
Reading and writing only.
What You Notice:
A gulf and a bay are the usual confusion, and the difference is how deeply the water cuts into the land.
Did you know
The Great Barrier Reef is large enough to be seen from space, covering roughly 350,000 square kilometres off the north-eastern coast of Australia.
The Bay of Bengal is the largest bay in the world, and it influences the climate around it as well as carrying trade.
The Suez Canal is a few tens of kilometres of cutting that shortened the voyage from India to Europe by thousands of kilometres.
Memory tricks
The five named waters — ENCLOSED, DEEP, BROAD, NARROW, CUT — A sea is partly enclosed, a gulf cuts deep, a bay opens broad, a strait is narrow, and a canal was cut by people.
Why reefs matter — SMALL SPACE, QUARTER OF THE LIFE — Reefs occupy a tiny fraction of the sea and shelter about a quarter of its species, so the loss is never proportional to the area.
Practice MCQs with answers (25)
- A a strait
- B a reef
- C a trench
- D a gulf
Show answer
Why:
A natural one may be rock, or built by corals.
- A a colony of algae growing on rock
- B a kind of underwater plant
- C a mineral deposit left by currents
- D a very small sea animal
Show answer
Why:
The reef is what those animals built.
- A they are among the most diverse ecosystems on Earth
- B they are found only in the warmest tropical waters
- C they contain more plant life than any other habitat
- D they produce most of the oxygen in the oceans
Show answer
Why:
A quarter of all ocean species depend on them.
- A a half
- B a quarter
- C a tenth
- D three-quarters
Show answer
Why:
In a very small fraction of the sea's area.
- A the species could live anywhere in the sea
- B reefs are easier to replace than larger habitats
- C losing a reef costs far more than its size suggests
- D the sea's other habitats hold very little life
Show answer
Why:
The loss is not proportional to the area.
- A tuna, sharks, squid and plankton
- B whales, seals, penguins and krill
- C polar bears, walruses and seabirds
- D fish, crabs, turtles and sponges
Show answer
Why:
Four kinds, all dependent on the reef.
- A overfishing, pollution and climate change
- B shipping, tourism and underwater cables
- C dredging, desalination and oil drilling
- D aquaculture, salt farming and mining
Show answer
Why:
Which is why conservation is called crucial.
- A a natural cycle that repeats itself every few decades
- B changes in ocean water chemistry, largely caused by us
- C the feeding habits of the fish that live on the reef
- D the growth of larger corals shading out the smaller
Show answer
Why:
And the habitat of many animals goes with it.
- A north-eastern Australia, over 20,000 kilometres
- B north-western Australia, over 2,000 kilometres
- C north-eastern Australia, over 2,000 kilometres
- D southern Australia, over 350 kilometres
Show answer
Why:
Covering some 350,000 square kilometres.
- A Both true, and the reason explains the assertion
- B Both true, but the reason does not explain it
- C The assertion is true and the reason is false
- D The assertion is false and the reason is true
Show answer
Why:
The assertion is sound. The reason is false, and inverts the point: reefs occupy a very small fraction of the sea, and holding about a quarter of its species in that fraction is exactly why the loss is out of proportion.
- A as a site closed to all human visitors
- B as a national park of Australia alone
- C as a protected fishing ground only
- D as a UNESCO World Heritage Site
Show answer
Why:
Hundreds of coral species live in it.
- A a sea
- B a gulf
- C a bay
- D a strait
Show answer
Why:
Partly enclosed is the operative phrase.
- A a sea, narrower and reaching further in
- B a bay, which is broader and reaches in less far
- C a strait, broader and shallower than it is
- D a canal, which is deeper but very much shorter
Show answer
Why:
Both are inlets, and the shape decides the name.
- A a sea with the Suez, a canal with the Arabian
- B a bay with the Strait of Malacca, a gulf with Bengal
- C a bay with the Bay of Bengal, a strait with Malacca
- D a strait with the Persian Gulf, a gulf with Malacca
Show answer
Why:
Each name describes a different shape.
- A a strait carries trade; a canal carries only water
- B a strait was cut by people; a canal is natural
- C a canal joins oceans; a strait joins only seas
- D a canal was cut by people; a strait is natural
Show answer
Why:
Malacca is natural; Suez was dug.
- A the shape of the gulf, and only then about history
- B the politics of the region through those centuries
- C the goods that each side happened to want
- D the ships that were available at the time
Show answer
Why:
Geography sets the terms history works within.
- A an open shore is always too shallow for large ships
- B the land around a bay shelters ships from open-ocean winds
- C a bay is closer to the centre of a country's trade
- D the water inside a bay is always calmer because it is fresher
Show answer
Why:
Which is why ports and dockyards cluster there.
- A Hudson Bay
- B the Bay of Biscay
- C the Bay of Bengal
- D the Bay of Fundy
Show answer
Why:
Home to a wide variety of plants and animals.
- A 1914, joining the Mediterranean to the Atlantic
- B 1869, joining the Arabian Sea to the Red Sea
- C 1914, joining the Red Sea to the Mediterranean
- D 1869, joining the Red Sea to the Mediterranean
Show answer
Why:
Creating a route from the Indian Ocean to Europe.
- A I, II and III are all correct as stated above
- B I and II only, since a longer route is shorter in time
- C II and III only, since the canal is a natural strait
- D I only, since it joins the Arabian Sea instead
Show answer
Why:
A canal is cut; a strait is not.
- A sail the whole way around Africa
- B unload and cross Egypt by land
- C sail around the southern tip of India
- D sail only when a seasonal wind turned
Show answer
Why:
The canal removed that entire detour.
- A it shows that canals are much cheaper than long voyages
- B it is geography being altered rather than merely used
- C it proves that Africa is smaller than it appears
- D it explains why straits are no longer important
Show answer
Why:
The clearest such case in the chapter.
- A sailors in past centuries used several different words
- B each of them is found in a different ocean of the world
- C each name describes a different shape of water and coast
- D the names record which sailor first charted each one
Show answer
Why:
The system is not a whim but a description.
- A neither has any effect on trade or transport
- B both of them were formed by the same geological process
- C both are found only in tropical latitudes
- D human action can wreck a sea feature or create one
Show answer
Why:
Bleaching on one side, the Suez on the other.
- A a shape on a coast predicts what the water can be used for
- B names exist so that maps can be printed consistently
- C the names were agreed by treaty between the trading nations
- D a classification makes every water body equally useful
Show answer
Why:
An inward curve is a usable harbour.
Important short questions (7)
A ridge at the sea's surface or just beneath it, thrown up by nature or by people. A natural reef may be a ridge of rock, or it may have been built by corals.
Because reefs are among the most diverse ecosystems on Earth. They feed and shelter about a quarter of all ocean species in a very small fraction of its area.
Changes in the chemical make-up of ocean water, largely caused by human actions. The coral loses colour and dies, and the habitat of many sea animals is lost with it.
It lies off north-eastern Australia, runs over 2,000 kilometres. It covers about 350,000 square kilometres and is a UNESCO World Heritage Site.
Both are inlets of the sea. A gulf is large and cuts deeply into the land; a bay is smaller and broader, reaching in less far.
A strait is a narrow natural channel joining two seas or oceans, such as the Strait of Malacca. A canal is cut by people, such as the Suez Canal.
Because the land curving round a bay shelters a harbour from the strong winds of the open ocean. That lets ships load and unload in safety.
Long answer questions (3)
A reef is a ridge at or near the surface of the sea, either natural or made by people. A natural one may be rock, or built by corals, which are tiny sea animals. Reefs are among the most diverse ecosystems on Earth. They are called the rainforests of the sea because they feed and shelter about a quarter of all ocean species, among them fish, crabs, turtles and sponges. Overfishing, pollution and climate change threaten them. Bleaching follows chemical change in the water, caused largely by people. It kills coral and removes that habitat.
A sea is a large, partly enclosed area of salt water joined to an ocean, such as the Arabian Sea. A gulf is a large inlet cutting deeply into land, such as the Persian Gulf. A bay is a smaller and broader inlet, such as the Bay of Bengal, which is the largest bay in the world. A strait is a narrow natural channel joining two seas or oceans, such as the Strait of Malacca. A canal is a channel people have cut to connect water bodies, such as the Suez Canal.
The shape decides what the water can be used for. It does so before anybody decides to use it. A bay is a broad inlet. The land curving round it shields a harbour from the strong winds of the open ocean. That is why ports and dockyards sit in bays rather than on exposed shores. The Persian Gulf has carried trade between India and Europe for thousands of years. That is a fact about its shape before it is one about history. Where no shape served, people cut one: the Suez Canal.
Flashcards (17)
Play this topic
- Match each water body to its example
- Natural, or made by people?
- Fact or myth
- Match each fact to the Great Barrier Reef
- Put the canal's effect in order
A Tour of the Continents
The roof of the world, a boundary somebody agreed on, a river that crosses a desert, a forest that waters itself, and the short list of processes behind all of it.
What you will be able to do
- Locate and describe the main features of Asia and Europe.
- Explain why the Asia-Europe boundary is an agreement rather than a discovery.
- Explain how the Nile, the Amazon and the Atacama each show water or its absence at work.
- Contrast what a canyon and a geyser each record about the Earth.
- Name the processes that produce every landscape, and match landforms to them.
Key points
Asia is the largest continent, and the Tibetan Plateau, the roof of the world, lies above the ranges bordering India; it moves the weather because it heats and cools as one vast block.
The Gobi is a cold desert of Mongolia and northern China, and the Steppes a flat treeless grassland belt across the middle of Asia.
The Urals are taken as the Asia-Europe boundary by agreement, since the two are one continuous landmass.
The European Plain is low and fertile, which drew farming, dense settlement and armies alike; the Alps divide the south.
The Sahara is the largest hot desert, with savannah to its south, and the Nile crosses it carrying water from elsewhere.
The Amazon carries more water than any river and feeds the largest rainforest, which makes part of its own rainfall.
The Atacama is among the driest places on Earth despite lying on a coast, because mountains and a cold current both block rain.
A canyon records time by slow removal from above; a geyser records depth, being fed by heat from inside the Earth.
Antarctica is almost all ice, the coldest place on Earth, with no permanent population and Indian research stations.
Full explanation
Why take a tour at all
The point is not to collect names. It is to see that the same few processes, repeated on different scales, produce every landscape on Earth: water, wind, ice, heat and the slow collision of the ground itself.
Asia, and the roof of the world
Asia is the largest continent and holds the highest ground. The Tibetan Plateau is called the roof of the world, and it sits above the ranges that hem India in on the north.
Why a plateau matters more than a peak
A peak is a point. A plateau is a vast high surface, and its size is what gives it power over the weather: it heats and cools as a block, and the air above it moves accordingly. That is how ground far from India helps decide India's seasons.
Asia's dry middle
Inland Asia, far from any ocean, is dry. The Gobi is the cold desert of Mongolia and northern China, where the extremes between summer and winter are severe. The Steppes are a wide belt of grassland, flat and treeless, running across the middle of the continent.
Where Asia stops
The Ural Mountains are taken as the boundary between Asia and Europe. It is worth noticing that this is a decision rather than a discovery: the two continents are one landmass, and the Urals are where people agreed to draw the line.
Europe, mostly flat
The great feature of Europe is the European Plain, a long stretch of low, fertile land running west to east. Farming and dense settlement followed it, and so, repeatedly, did armies, because flat country is easy to cross.
And the wall across it
The Alps run across southern Europe and are the continent's main mountain system. They give Europe its sharpest internal division: the climate, the crops and the languages differ on either side of them.
Africa and the largest hot desert
The Sahara spreads across northern Africa and is the largest hot desert in the world. South of it the land changes to savannah, tropical grassland with scattered trees, which is where the great herds live.
The river that crosses the desert
The Nile runs north through the eastern Sahara to the Mediterranean and is among the longest rivers on Earth. A river crossing a desert is worth pausing on. The water is not from the desert; it is passing through. That is how a narrow green strip can support a civilisation in the middle of sand.
South America, and the largest rainforest
The Amazon basin holds the largest tropical rainforest on Earth, fed by the Amazon, which carries more water than any other river. The forest's rainfall is partly its own: water that rises from the trees falls again further inland.
The driest place there is
The Atacama Desert in Chile is among the driest places on Earth, and parts of it have gone years without measurable rain. It lies on a coast, which is the surprise, and the reason is that the mountains and the cold current offshore both work against rain.
North America, cut and heated
The Colorado Plateau carries the Grand Canyon, which the Colorado river cut down through rock over an immense span of time. Yellowstone sits over a heat source in the Earth, which is why its geysers throw hot water into the air.
Two ways to read a landscape
The canyon and the geyser answer different questions. A canyon is a record of time: slow removal, from the top down. A geyser is a record of depth: heat from far below reaching the surface. One is carved and the other is fed.
Australia, dry in the middle
Most of Australia's interior is desert or semi-desert, and the population lives around the edges. The Great Barrier Reef lies off the north-east, and the continent's isolation has left it with plants and animals found nowhere else.
Antarctica, the exception
Antarctica is covered almost entirely by a thick ice sheet, is the coldest place on Earth and has no permanent human population. It is used for scientific research, and India maintains stations there.
What the tour was for
Every landscape above was made by the same short list: running water, blowing wind, moving ice, heat from inside the Earth, and plates pushing together. A mountain is the collision, a plain is what water left, a desert is where rain does not reach, and a canyon is what a river removed.
And why it concerns a student in India
Because the systems do not stop at borders. The Tibetan Plateau bears on the monsoon, an ocean current decides how mild a distant coast is, and a canal cut in Egypt sets the shortest route from an Indian port to Europe. The geography of the Earth is one subject, not a list of places.
Concepts and terms
A vast raised surface of land, as against a single peak. Because it heats and cools as one block, it moves the air above it and so affects weather far away.
The Urals divide Asia from Europe by convention. The two are one landmass, so the line was settled by agreement rather than found by survey.
The Nile's water is not from the Sahara but passing through it, which is how a narrow green strip can support a civilisation in sand.
In the Amazon basin, water rising from the trees falls again further inland, so part of the rainfall is produced by the forest itself.
A canyon is carved from above by slow removal and records time. A geyser is fed from below by heat inside the Earth and records depth.
Traps to avoid
Common misconceptions
A desert full of clothes
Scenario:
The Atacama is among the driest places on Earth, and its rocky, Mars-like ground has been used by NASA to test rovers. Its skies are so clear that astronomers travel there to look at them. The same desert has also become one of the fastest-growing dumps for discarded clothing anywhere in the world. The clothes come from fast fashion, which copies trends quickly and cheaply, usually made where wages are low, and is thrown away as soon as the trend moves on. The United Nations has called the waste an environmental and social emergency.
Analysis:
The same place can be scientifically precious and used as a rubbish heap, and noticing both at once is what the chapter is asking for.
Activity:
Find out where clothes given away in your own town actually end up.
Build a continent card set
Title:
Build a continent card set
Safety:
Writing only.
What You Notice:
Most people know the continent they live on best, and the gaps are usually the two polar ones.
Did you know
Parts of the Atacama Desert in Chile have gone years without any measurable rainfall, and it sits beside the Pacific Ocean.
Antarctica has no permanent human population at all, and India maintains research stations on it.
The Amazon carries more water than any other river on Earth, and the forest it feeds makes part of its own rain.
Memory tricks
The processes behind every landscape — WATER, WIND, ICE, HEAT, COLLISION — A mountain is the collision, a plain is what water left, a desert is where rain does not reach, and a canyon is what a river removed.
Two deserts, two reasons — GOBI IS FAR, ATACAMA IS BLOCKED — The Gobi is dry because it lies far inland from any ocean. The Atacama is dry on a coast because mountains and a cold current block the rain.
Practice MCQs with answers (25)
- A the Deccan Plateau, lying south of the Vindhyas
- B the Tibetan Plateau, the roof of the world
- C the Colorado Plateau, cut by a canyon
- D the Anatolian Plateau, west of the Urals
Show answer
Why:
It bears on India's seasons from outside India.
- A a peak is colder at the top than a plateau ever becomes
- B a plateau always stands considerably higher than any peak does
- C a plateau is a vast surface heating and cooling as a block
- D a peak is made of rock while a plateau is made of soil
Show answer
Why:
Size is what gives it power over the air above.
- A the Gobi, which is a cold desert
- B the Sahara, which is a hot desert
- C the Atacama, which is a dry coast
- D the Thar, which is a sandy desert
Show answer
Why:
Inland Asia is dry because it is far from any ocean.
- A the Savannah
- B the Steppes
- C the Prairies
- D the Pampas
Show answer
Why:
Flat and without trees, across the continent.
- A it follows the deepest river valley in the region
- B it was fixed by the height of the range itself
- C it is a decision people agreed on, not a discovery
- D it marks where two separate landmasses actually meet
Show answer
Why:
Asia and Europe are one continuous landmass.
- A the Steppes, which lie east of the Ural range
- B the Alps, which divide the whole south of the continent
- C the Urals, which mark the edge of the continent
- D the European Plain, which is low and easy to cross
Show answer
Why:
Flat fertile country invites both the plough and the army.
- A the Alps
- B the Urals
- C the Andes
- D the Atlas
Show answer
Why:
The continent's sharpest internal division.
- A the Gobi, in Asia
- B the Sahara, in Africa
- C the Atacama, in Chile
- D the Mojave, in America
Show answer
Why:
Savannah lies to the south of it.
- A tundra
- B steppe
- C savannah
- D taiga
Show answer
Why:
The land changes as you move south from the desert.
- A the Mediterranean sends moist air south into the desert
- B the desert there receives far more rain than elsewhere
- C the sand in that region holds water near the surface
- D the Nile's water is not from the desert but crossing it
Show answer
Why:
A river crossing a desert is water passing through.
- A the Amazon
- B the Nile
- C the Mississippi
- D the Ganga
Show answer
Why:
It feeds the largest tropical rainforest.
- A the river evaporates and returns as rain on the coast
- B water rising from the trees falls again further inland
- C the forest traps the rain that the ocean sends inland
- D rain falls only where the forest has been cleared away
Show answer
Why:
Which is why clearing it changes the rainfall.
- A the heat of the desert evaporating rain before it lands
- B the absence of any large river anywhere in the region
- C mountains and a cold offshore current both blocking rain
- D the coast facing away from every wind that could carry rain
Show answer
Why:
Parts of it have gone years without measurable rain.
- A the Deccan Plateau, cut by a very old river
- B the Colorado Plateau, cut by a moving glacier
- C the Tibetan Plateau, cut through by the Colorado river
- D the Colorado Plateau, cut by the Colorado river
Show answer
Why:
Cut down through rock over an immense span of time.
- A a source of heat inside the Earth beneath it
- B a very deep lake lying underneath the park
- C the pressure of the ice that once covered it
- D a river running through hot rock at the top
Show answer
Why:
Heat from below reaching the surface.
- A the canyon records depth, the geyser records time
- B the canyon records time, the geyser records depth
- C both of them record the passage of very long time
- D both of them record heat rising from deep below
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Why:
One is carved from above, the other fed from below.
- A in the north-east, because the reef shelters the coast
- B across the interior, because the coasts are far too wet
- C around the edges, because the interior is mostly desert
- D in the centre, because the rivers gather in the middle
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Why:
The interior is desert or semi-desert.
- A the absence of any mountain ranges on the island
- B the great size of the deserts across its interior
- C the shelter that the Great Barrier Reef provides
- D the long isolation of the continent from the others
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Why:
Separation let them develop on their own.
- A I, II and III are all correct as stated above
- B I and II only, since some families live there
- C II and III only, since much of it is bare rock
- D I and III only, since the Arctic is colder still
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Why:
It is used for research; India has stations there.
- A Both true, and the reason explains the assertion
- B Both true, but the reason does not explain it
- C The assertion is true and the reason is false
- D The assertion is false and the reason is true
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Why:
The assertion is false: Asia and Europe are one landmass, so no such meeting place exists to be surveyed. The reason is true, and the boundary is an agreement rather than a discovery.
- A water, wind, ice, heat and colliding plates
- B rain, snow, rivers, lakes and ocean currents
- C erosion, farming, building, mining and roads
- D sunlight, gravity, tides, seasons and storms
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Why:
A short list, repeated at different scales.
- A what water left, a collision, what a river removed, where rain fails
- B a collision, what water left, where rain fails, what a river removed
- C where rain fails, what a river removed, a collision, what water left
- D what a river removed, where rain fails, what water left, a collision
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Why:
Each landform names the process that produced it.
- A because Indian rivers begin outside the country
- B because India has territory on several continents
- C because these systems do not stop at any border
- D because the examination covers the whole world
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Why:
The plateau, a current and a canal all reach India.
- A the isolation of Australia from other continents
- B the Alps dividing the climates of southern Europe
- C the Atacama staying dry despite lying on a coast
- D the Tibetan Plateau bearing on the monsoon winds
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Why:
Ground outside India helps decide India's seasons.
- A to show a few processes repeating at different scales
- B to compare the sizes of the seven continents fairly
- C to establish which continent holds the most people
- D to record the names a student is expected to recall
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Why:
The point is not to collect names.
Important short questions (7)
It is a vast high surface above the ranges on India's north. It heats and cools as a block and moves the air above it, so ground outside India helps decide India's seasons.
The Gobi is a cold desert in Mongolia and northern China with severe seasonal extremes. The Steppes are a flat, treeless belt of grassland across the middle of Asia.
Because the two are one continuous landmass. The Urals are simply where people agreed to draw the line, so the boundary was settled rather than found.
Farming and dense settlement followed it, because the land is fertile. Armies followed it repeatedly too, because flat country is easy to cross.
If a river crosses it. The Nile's water is not from the Sahara but passing through it, so a narrow green strip can support settlement in the middle of sand.
It is surprising because the desert lies on a coast. The mountains and the cold current offshore both work against rain reaching it.
A canyon records time, cut by slow removal from the top down. A geyser records depth, fed by heat from far below reaching the surface.
Long answer questions (3)
Asia is the largest continent and holds the highest ground. The Tibetan Plateau is the roof of the world. It sits above the ranges on India's north and moves the air above it as a block. Inland Asia is dry: the Gobi is a cold desert of Mongolia and northern China, and the Steppes are a flat treeless grassland belt. The Urals are taken as the boundary with Europe, by agreement rather than discovery. Europe's great feature is the European Plain, low and fertile, which drew farming, settlement and armies alike. The Alps cross the south and divide its climates.
The Nile crosses the eastern Sahara to the Mediterranean. Its water is not from the desert but passing through, which is how a narrow green strip supports a civilisation in sand. The Amazon carries more water than any other river. It feeds the largest tropical rainforest, which makes part of its own rain, since water rising from the trees falls again inland. The Atacama is among the driest places on Earth, although it lies on a coast. Mountains and a cold offshore current both work against rain.
The purpose is not to collect names. It is to show a few processes repeating at different scales. Running water, blowing wind, moving ice, heat from inside the Earth and colliding plates are the whole list. They account for every landscape in the chapter. A mountain is the collision. A plain is what water left. A desert is where rain does not reach, and a canyon is what a river removed. It concerns a student in India because these systems cross borders. The Tibetan Plateau bears on the monsoon. A current decides a distant coast's climate, and a canal in Egypt sets the route to Europe.
Flashcards (17)
Play this topic
- Match each feature to its continent
- Desert, grassland, or forest?
- Fact or myth
- Match each landform to the process that made it
- Build the Grand Canyon
Class 8 Social Science Chapter 8 — frequently asked questions
A nearly spherical shape that swells around the middle and is pressed in at top and bottom. The Earth is one because it spins.
That a curved surface cannot be laid flat without tearing or leaving gaps. Every flat map of the Earth must distort something.
The business of turning a round Earth into a flat drawing. It is a method with a stated cost, which decides what the map can report truly.
About 71 per cent is the share of the Earth's surface they cover. About 97 per cent is the share of the Earth's water they hold.
They support life, regulate climate, and add moisture to the air. They regulate climate by absorbing heat and releasing it slowly, because water changes temperature only slowly.
Because it carries ranges, troughs and flats just as the land does, along with deep V-shaped trenches. Water hides all of it from view.
A ridge at the sea's surface or just beneath it, thrown up by nature or by people. A natural reef may be a ridge of rock, or it may have been built by corals.
Because reefs are among the most diverse ecosystems on Earth. They feed and shelter about a quarter of all ocean species in a very small fraction of its area.
Changes in the chemical make-up of ocean water, largely caused by human actions. The coral loses colour and dies, and the habitat of many sea animals is lost with it.
It is a vast high surface above the ranges on India's north. It heats and cools as a block and moves the air above it, so ground outside India helps decide India's seasons.
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