NOTES/ SOLUTIONS/ QUESTIONS ANSWERS: GEOGRAPHY PTB CLASS-6
CH:1 EARTH AS A PLANET
Q.1: Describe universe and its components.
Ans: UNIVERSE AND ITS COMPONENTS
WHAT IS UNIVERSE?
According to the astronomers, the creation of the universe came into existence as a result of a large single explosion about 15 to 20 billion years ago. This is called Big Bang. The universe is made up of billions of galaxies comprised of matter.
MILKY WAY
The Milky Way is a galaxy. It is a collection of billions of stars, gases and clouds of dust.
SOLAR SYSTEM
The sun is one of the billions of stars in the Milky Way Galaxy. Eight planets revolves around the sun. This is called Solar System.
EARTH
Our earth is one of the eight planets which revolves around the sun on their respective heavenly tracks. These heavenly tracks are called orbits.
Q.2: What is solar system? And how it originated?
Ans: The word solar means “of the sun”. The solar system is made up of eight planets which revolve around the sun in their respective orbits. The shape of the solar system is somewhat like a saucer. It originated about 5 billion years ago when a cloud of gas and dust began to spin. With the passage of time, the gaseous material began to cool appeared in the shape of solar system. The sun originated in the centre as the largest member of this system. After being cooled, the circulating gases and dust became planets, which began to revolve around the sun.
SUN:
Sun is a bright star. It is made up of hydrogen and helium gases. The temperature of its outer surface is about 6000o centigrade. Every planet of this system received light and heat from the sun.
PLANETS
The planets which revolve around the sun received light and temperature from it. The earth on which we live is one of those planets which revolves around the sun in about 365 days and 6 hours.
Q.3: Describe the shape and size of earth.
Ans: SHAPE OF EARTH
Earth is round in shape like a football but slightly flat at the north and south poles. If we travel in any direction on the earth, we shall reach the same place from where we started our journey.
SIZE OF EARTH
If we cut the earth along the equator into two equal halves, the distance from one end to the other one is about 12750 kilometers. This is the diameter of the earth. The equator is an imaginary line around the earth at an equal distance from the north and south poles, which divides the earth into two equal halves.
If we travel the equator and take a complete round, the distance will be about 40,000 kilometers. This is the circumference of the earth.
The total area of the surface of the earth is about 510 million square kilometers.
Q.4: Describe the movement of the Earth.
Ans: There are two types of movements of the earth at the same time:
Rotation
Revolution
(i) ROTATION
The earth moves around its axis. The characteristics of this movement are as under:
It moves from west to east.
Its speed is about 100kms per hour.
The earth moves on its axis and takes a complete rotation around it 24 hours.
Days and nights are formed as a result of this rotation.
(ii) REVOLUTION
The earth moves around the sun in the orbit. This movement is called
This movement is anti-clockwise.
It moves at a speed of 107,000 kms per hour.
The earth takes a complete revolution around’ the sun in its orbit in about
365 days and 6 hours.
Seasons are formed as a result of this movement.
The orbit in which the earth moves around the sun is oval in shape.
Q.5: How day and night are formed?
Ans:
The earth takes a complete rotation around its axis in 24 hours. As a result of this movement day and night are formed. As the earth is round in shape and is moving around its axis, its half portion remains in front of the sun for a specific time. The other half portion is away from the sun. The half portion which is in front of the sun experiences day and the other half portion which is away from the sun experiences night. Due to this rotation the day and night are constantly interchanged. This can be easily explained by the following experiment. Hang a football with a string and throw light on it from a distance of 5 feet. You will see that half portion of football is illuminated and its rear half is in darkness. Now, rotate the football slowly, you will see that the darked portion is coming into light and the illuminated portion is going into darkness. Days and nights are interchanged in the same way.
Q.6 Describe change in the length of days and nights.
Ans: The earth’s axis is tilted at an angle of 66.5°. Owing to this tilt the length of days and nights change. The portion of the earth which is tilted towards the sun, the days are longer in that portion. The days are shorter in the portion which is tilted away from the sun. In the Northern Hemisphere when days are longer and nights are shorter, at the same time in the Southern Hemisphere the days are shorter.
In the same way, when days -are shorter and nights are longer in the Northern Hemisphere the days fare longer and nights are shorter in the Southern Hemisphere.
On 23 September and 21st March, the sun is above the horizon twelve hours and below it twelve hours. The day and night period are equal i.e., of twelve hours.
Q7. How seasons are changed? Describe seasonal variation in the Northern and the Southern Hemisphere.
Ans: Every year the seasons change. The earth revolves around the sun tilting to one side at an angle of 23.5. This means that the first half portion of the earth and then the other-leans towards the sun.
On -June 21, the Northern Hemisphere is tilted towards the sun, during this period the Southern Hemisphere is away from the sun. That’s why there is summer in the countries of the Northern Hemisphere and winter in the countries of the Southem Hemisphere.
On December 22, the opposite happens to both hemispheres as the Earth’s tilt changes. The Southern Hemisphere is tilted towards the sun, while the Northern Hemisphere is away from the sun. As a result of that there is summer in the Southern Hemisphere and winter in the Northern Hemisphere.
In some countries near the equator it is hot all year round, and the sun is always-high overhead, while in the Polar Regions temperature mostly remains below the freezing point.
On 21st March and 22nd December, neither the Northern Hemisphere nor the Southern Hemisphere is titled towards the sun. That’s why the season is neither too hot nor too cold in both hemispheres.
Q.8: Describe the phenomena of solar and lunar eclipse.
Ans: The earth moves around the sun and the moon moves around the earth.
During this revolution sometimes the moon comes between the sun and the earth. As a result of that the sun is not seen completely or partially from the earth. This is called solar eclipse.
Sometimes during this revolution the earth comes between the sun and the moon and casts its shadow on the moon, due to which the moon is not seen completely or partially from the earth. This is called the lunar eclipse. This can be easily explained by the following example.
Light a bulb and what is with one eye closed. Now take s coin in your hand and bring it near your eye in such a way that the coin comes between the eye and the bulb. Now tell:
(ii) Is the bulb being seen?
No, it is not being seen, the light of the bulb is falling on the coin. Remember! Solar and lunar eclipse occur in the same way.
Q.9: Write a note on the continents.
Ans: The land portion of the earth is about 29 percent. It comprises of seven large masses which are called continents. These are:
ASIA
It is the largest continent. In its east lies the Pacific Ocean, in the West the continent of Europe, in the north the Northern Ocean and in the South Of it lies the Indian Ocean.
AFRICA
It is the second largest continent. In its east is the Indian Ocean, in the west the Atlantic Ocean, in the north the Mediterranean Sea and in the south lies the Southern ocean.
III. NORTH AMERICA
North America is the third largest continent. In its east is the Atlantic Ocean in the West the Pacific Ocean, in the north the Northern Ocean and in its south lies the continent of South America.
SOUTH AMERICA
South America is the fourth largest continent. In its east lies the Atlantic Ocean, in the west is the Pacific Ocean, in the north the Northern Ocean and in the south lies the continent of South America. Sometimes, the temperature falls to -60 centigrade.
ANTARCTICA
Antarctica is the fifth largest continent. It lies around the South Pole. Due to its extreme cold climate, it is the only uninhabited continent.
VII. EUROPE
Europe is the sixth largest continent. In its east lies Asia, in the west the Atlantic Ocean, in the north lies the Northern Ocean and in the south the Mediterranean Sea.
VII. AUSTRA
Australia is the smallest continent. In its east» and north is the Pacific Ocean, in the west and south lies the Indian Ocean. ‘
Q.10: Write a short note on the oceans of the world.
Ans: A huge mass of water is called ocean. There are five oceans in the world, which are:
(i) PACIFIC OCEAN
It is the largest ocean. In its east the countries of North and South America are situated and in the West lies the continents of Asia and Australia.
(ii) AHANTIC OCEAN
It is the largest ocean of the world. In its east lie the continents of Europe and Africa. In the West are North and South America.
(iii) INDIAN QCEAN
It is the third largest ocean of the world. In its east is the continent of Australia, in the West lies Africa, in the north is Asia and in the south the Southern Ocean.
(iv) SOUTHERN OCEAN
It is the fourth largest ocean of the World. It lies around the South Pole and is extremely cold.
(v) NORTHERN OCEAN
It is the smallest ocean of the world. It lies around the North Pole. Like the Southern Ocean it is also extremely cold.
CH: 2 GLOBE, MAPS AND THEIR USES
Q.1: Define a Map and Globe. Also write what is the difference between map and globe.
Ans: DEFINITION OF GLOBE
A globe is an object shaped like a football with a map of the world drawn on its surface. It is usually on a stand so that it can be turned.
A map is a representation, upon a flat surface (paper) of the whole earth or some part of it according to a given scale. It just seems as you are looking at that place from a height overhead.
Difference between Globe and Map
The basic difference between globe and map is given below:
A globe is round in shape and a map is flat.
A globe represents the whole earth while a map can represent the whole world or some part of it.
A globe cannot represent much details while a map can represent every minute detail such as countries, towns, rivers, lakes, buildings etc.
Q.2: What is the importance of a map?
Ans: Our earth is a big place. What is its shape and size? Where do we live on it? What is the type of the place where we live? What type of places are around us? What type of connection with our surrounding places?
Q.3: What are the components of maps? Also write a note on latitude and longitude?
Ans: The following characteristics are found in a map:
A map shows directions.
A map has a scale.
Latitudes and longitudes are shown on a map.
By conventional signs land forms are shown on a map.
Let’s have a detailed look on these components.
DIRECTIONS
The top of the map represents north, the opposite side south, the right hand side east and the left hand side west. These are primary directions. These are called Cardinal Points. There are four more directions between the Cardinal points. These are called secondary direction of With the help of the directions we can find on which side a place is situated with reference to the other.
ACTIVITY
Observe the map and answer the following questions:
Name the country in the east of Pakistan.
In which direction Arabian Sea is situated from Pakistan?
iii. Name the two countries which are situated in the west of Pakistan.
What is the direction of China from Pakistan?
Ans. (i) India (ii) South (iii) Afghanistan and Iran (v) North .
TYPES OF NORTH
The north is the basic important direction on the map. North is of two a types.
GEOGRAPHICAL NORTH
The direction in which the North Pole is situated is the Geographical North. It is detected by the Polar star which always remains over head north pole.
MAGNETIC NORTH
Our earth has a magnetic characteristic like a magnetic bar it also has two ends, i.e. magnetic north and magnetic south. Magnetic north is traced by an instrument known as magnetic compass. Magnetic north is situated near North Pole in the Canadian island of Prime Wales.
iii. SCALE
It is impossible for a map to show every inch of land. Therefore, scaling is necessary and a ratio is established between ground and map distance. This is called scale.
To understand scaling here is a map of a classroom, the scale of classroom represents 8 metres on ground by 8 cm on paper, which that 1 metre on ground is shown by 1 cm on the plan.
TYPES OF SCALE
Scale can be shown by the following three methods:
As a statement i.e.,
1 cm : 1 metre
This is called statement of scale.
As fraction i.e. 1cm: 100cm
It means that 1cm represents 100 cm. This is called Representative Fraction (R.F).
iii. As a horizontal line which shows the ration between ground and map distance.
This is called Linear Scale
Latitude and Longitude
The location of places on land is shown by latitude and longitude on a map.
LATITUDE
The line on a map which divides the earth into Northern and Southern hemisphere is called Equator.
The angular measurement of a place taken it the equator is shown by these lines. This is the distance of a place north or south of the equator. These lines are drawn parallel to the equator. These are called Latitude. There are 180o latitudes from north pole to south pole, 90o in the north of equator and 90o in the south of Equator.
LONGITUDE
The line on a my which divides the earth into Eastern hemisphere and Western hemisphere is called Prime Meridian. It is also called Greenwich because it passes on the map through Greenwich, a place in London. The angular measurement of a place taken from Prime Meridian is shown by lines. These lines join one another at north and south poles.
Remember! There are 360° longitudes. 180° in the east of Prime Meridian and 180° in the west of Prime Meridian up to International Date Line.
Q.4: How the location of place is found on a map with the help of latitude and longitude?
Ans: Location of a place on a map is found with the help of latitude and longitude. The places with north latitude are searched in the Northern hemisphere and places having south latitude are searched out in the Southern hemisphere. Likewise, the places with east longitude are searched in the east -of Greenwich Meridian. The places having west longitude are searched in the west of Greenwich Meridian.
Q.5. Write a note on Time Zones.
The difference of time between two countries is calculated with the help of longitude. There are 360° longitudes which pass in front of the sun in 24 hours due to the rotation of the earth.
The speed ism 15° longitudes per hour, the formula is 360/24 = 15 longitudes per hour.” According to this formula’ there is a difference of one hour after every 15° longitudes. Due to the direction of rotation of the earth from west to east, the time is 1 hour ahead towards east and 1 hour back towards west after every 15° longitudes. Due to difference of time the world has been divided into zones of 15° longitudes each. These are called Time Zones. The time is the same in each zone.
PROCEDUE OF CALCULATING TIME DIFFERENCE
If time in Greenwich is 12:00 Noon, find the time of Lahore (Pakistan).
The longitude of Lahore is‘ 75°E.
The difference of time between Greenwich and Lahore =
=
Because Lahore is situated in the east of Greenwich (Prime Meridian), its time would be 5 hours ahead.
So 12:00 + 5 = 17:00 which means 5:00 pm.
(Note: We would subtract the time difference from the Green which time, if the place lies in the west of Greenwich).
Q.6: Write a note on the International Date.
If we travel towards east from the Prime Meridian (Greenwich Meridian),
then at longitude the time will be 12 hours ahead If we travel towards west, then at 180° the time will be 12 hours back. So at 180° longitude the time difference is exactly 24 hours. Due to this 180° longitude has been designated as International Date Line. If you cross the International Date line from east to west there you are a full day ahead and if you cross it from west to east you are a full day back.
Q.7: What are Conventional signs?
Ans: The physical and cultural landforms on the surface of earth are shown by symbols on the map. These symbols are called Conventional signs.
Q.8: Describe the ‘methods of showing relief on it map.
Landforms on the surface of the earth are shown on a map by different methods.
Some of these methods are:-
CONTOURS
Contours are the lines drawn on a map to show altitude. These lines on the map join areas of equal height from the sea-level.
LAYER TINTS
In some maps, different areas are shown by different colours. For example, plains and forests are shown by different shades of green colour, mountains by brown colour and snowy areas by white colours.
CONVENTIONAL SIGN
Physical and cultural landforms on earth are shown by conventional lines (symbols) on a map.
Q.9: Describe the uses (utilities) of maps.
Ans: The uses of maps are:
It tells us where we live on the earth.
A map is needed for tourism.
A map tells us about directions.
The scale of map helps us in understanding ground distances.
With the help of a map we keep in touch with different parts of the world.
It helps us in understanding different environments of the world.
The army does its war planning on maps.
Distribution of crops, minerals and industries is shown on maps.
Weather conditions of a region are shown on a map.
For land, water and air-travel maps are very useful as they provide guidance in the respect.
CH: 3 EARTH AS HOME FOR THE HUMAN BEING
Q.1: What is meant by natural environment? Also write what makes the earth habitable?
Ans: NATURAL ENVIRONMENT
Natural environment means physical landscape, climate, vegetation, animals, forests, seas, mountains, lakes, rivers, deserts etc., which surround us. Planet earth is the only home for human beings. It provides the natural environment on which not only the life of human beings depends but of all creatures that live on earth.
EARTH IS THE ONLY HABITABLE PLANET
The natural environment exists only on our earth. There is no life on other planets of the solar system. That is why, there is life on earth. Due to the presence of natural environment is inhabited while the other planets are inhabited. The following basic reasons make the earth habitable
There is a suitable temperature on the earth for all forms of life.
There is a huge mass of water on the earth that makes life possible.
Oxygen exists on earth which encircles atmosphere.
Q.2: Describe natural-spheres of the earth.
Ans: The following are the natural» spheres of the earth:
ATMOSPHERE
The mixture of different gases, water vapours and dust particles in the shape of an envelope surrounding our earth is called Atmosphere. These gases are:
Nitrogen, Oxygen, Carbon dioxide and Ozone etc.
Of all these gases oxygen is the most important gas because no human being can survive without it.
Carbon dioxide is the gas which plants use for their food and in return release oxygen.
There is a layer of ozone too, which shields our earth from the dangerous ultra-violet rays of the sun.
LITHOSPHERE
The area of the surface of the earth is 510 million square kilometers. Out of which about 29% is comprised of land, which is called Lithosphere.
Man lives on this portion.
There are mountains, valleys, forests on the lithosphere, which provide habitats for every kind of plants, animals and for all human beings.
It comprises of different types of rocks in which so many minerals are found. Human beings utilize these minerals for various purposes and industries.
On the soil of lithosphere natural vegetable flourishes and human beings grow crops for their food. Raw material of some crops is used in industries.
HYDROSPHERE
About 71% of the area of the surface of the earth is covered with water in the form of oceans, rivers and lakes etc. This is called Hydrosphere.
It is hydrosphere from Where the water vapours enter the atmosphere by the process of evaporation due to heat. These vapours are condensed into Water forming clouds and produce rain. Rain, hail and snow are the means by which water is returned to the earth, which is a source of survival for all forms of life on the earth.
BIOSPHERE
Biosphere is the part of the earth’s surface and atmosphere in which plants and animals can live. It is dependant upon the other three spheres.
Q.2: Write a note on the relationship of climate and human beings.
Ans: DIFFERENT CUMA TES
Our earth is of enormous size. The climate is not similar in all the parts of the world. There is a lot of variation in climate in different regions, due to which the diet, clothing and way of living of people is different in different parts of the World.
THINLY POPULATED AREA
More than earth’s surface is too humid, too dry or too cold. That is why it is thinly or least populated;
THICKY POPULATED AREAS
Thick population is found in the areas which are neither too hot or too cold.
AFFECTS OF CLIMATE
Climate is an outstanding factor in man’s life. It affects the colour, physical appearance and working capabilities of human beings.
Q.3: Write a note on physical landscape and human beings.
Ans: Adjustment of Life According to Environment
About 80% of the world population lives in plains. However, human beings are also settled in deserts and mountains. They have adjusted their lives according to the environment.
MOUNTAINS
The people living in mountains are hardy and physically strong because of difficult mountainous terrain.
As no flat land is available in mountainous terrain, slopes are cut into terraces for small scale cultivation of some crops like maize, rice, tea and fruit etc.
As no flat land is available, it is difficult to spread a network of road and railway.
Winter are harsh while summer are pleasant.
Forests are in abundance in mountains, so tree cutting is the main economic activity.
As summers are very pleasant in mountainous regions, these are considered beautiful.
PLAINS
Life is not so hard in plains. The land of plains is flat, so it allows cultivation on large scale, development of industries and transportation network.
Climate in plains is not too harsh, due to this reason these are thickly populated.
iii. DESERTS
The rainfall is very scanty in deserts. Due to lack of water, there is no vegetation in deserts. Cactus is found in deserts. Oases are found in deserts where plants and palms (date trees) grow due to the availability of water. People living in deserts roam in search of water and food and thus live a nomadic life.
Q.4: Write a note on water and human beings.
Ans: TRANSPORTATION IN ANCIENT TIMES
In earliest times there were no means of transportation. Early man used the floating log for his journey in waters. Then travelling in boats and ships he began to explore the world. Water is the basic necessity of life. So the earliest settlements took place near water bodies.
Water is present in different forms on ‘ the earth’s surface. Let’s have a look.
OCEANS AND SEAS
Oceans and Seas are natural sources of transportation. There are so many sea-ports in the world. Now-a-days journey and trade is done via sea routes. Mostly crude oil is exported and imported through oceans and seas. There is a variety of living organisms on ocean floors. Oceans and seas keep the climate moderate. There are so many kinds of sea-creature. Approximately, 85% of the fish- catch comes from seas and remaining
RIVERS
Rivers are not only used for irrigation purposes but also for transportation.
Dams are built on rivers to generate electricity. Electricity which is generated by the force of water is called hydro-electricity.
Rivers are also a source of fish catch.
The enchanting beauty of river valleys, water-falls and lakes attracts the tourist and enhance the economy of a country.
SPRINGS
Spring water is used for drinking and irrigation.
UNDERGROUND WATER
Underground water is taken out by wells and tube-wells for drinking and irrigation.
Q.5 Write a not on relationship between forests and human beings.
Ans: OLD RELATIONSHIP WITH HUMAN BEINGS
Since the earliest times, forests have been man’s great friend. They gave him food, shelter and clothing in the form of leaves.
MEDICINES AND DYES
Medicines and dyes are made from herbs, barks, roots and stems of some trees.
CHARCOAL
Charcoal is made from hardwoods.
PAPER PRODUCTS
Paper products are made almost entirely from pulpwood.
EARLY TRADE
In ancient times, trade and exploration was dependant upon ships made of wood.
FOR BUILDING PURPOSES
Wood is used for building purposes from boxes to bridges. Houses are constructed with wood in the mountains.
RUBBER
Rubber is also obtained from rubber trees, from which tyres and tubes are made.
SPORTS GOODS
Sports goods are made from mulberry trees.
HONEY
Honey 70% of the world honey comes from forests woods.
FURNITURE
Making of furniture is dependent on forest.
WILD LIFE
Wild life is also indebted to forests.
CLIMATE
Forests also affect the climate.
SOURCE OF OXYGEN
Forests provide oxygen.
WINDS AND FLOODS
Forests check the speed of winds and reduce velocity of flowing water.
Q.6: Write a note on human being and life on earth.
Ans: Human beings grow crop; catch fish, hunt birds and rear animals to get food and milk. Besides, they take work from animals according to the environment. Elephants are used for carrying wooden logs in forests, while camels are used for travelling and carrying loads in deserts. In ice-land dogs and reindeers are used to pull wooden sleighs. Oxen are used for ploughing the fields in plains.
Buffaloes, cows and goats are reared for milk and meat
Sheeps are reared in grasslands to get wool.
Silk-worms are reared on mulberry trees to get silk.
CH: 4 ROCKS
1: Define element.
An element is the simplest form of matter. All the things found in the world are made of elements.
Q.2: What are minerals?
Minerals are substance, which are naturally present in the earth like coal, iron, petroleum, salt, etc. These are composed of different in organic elements like oxygen, silicon, aluminum, iron, calcium, sodium, potassium and magnesium etc. Human beings used these resources for their benefit. Mineral resources are the basis for the development of modern industries
Q.3: What is meant by a rock? Also write a detailed note on igneous rocks.
Ans: DEFINITION OF ROCK
A rock is the hard solid material that forms part of the surface of the earth. It is a combination of two or more minerals. Some rocks are soft like shale (soft stone) and some are hard like diamond. In some rocks crystal are found and in some fossils of plants and animals. Fossils are the remains of animals or plants which have become hard and turned into a rock. Some rocks absorb water and some do not. The different characteristics of the rocks are dependent upon the way of their formation.
IGNEOUS ROCKS
Into the interior of the earth, the temperature increases. It is estimated that the temperatures 5000 centigrade in the centre. Because of high range of temperatures, the minerals are melted and a thick igneous matter magma is formed. Magma is a very hot liquid rock below the earth’s surface. When it pours out on the surface of the earth, it is called “Lava”.
TYPES OF IGNEOUS ROCKS
There are two types of igneous rocks according to their formation. These are:
(i) Intrusive Igneous Rocks
(ii) Extrusive Igneous Rocks
(i) INTRUSIVE IGNEOUS ROCKS
When the molten matter becomes solid inside the surface of the earth, the rock thus formed is called Intrusive Igneous Rock. Its other name is plutonic Rock. Granite, diorite and gabbro are intrusive igneous rock.
The molten matter inside the earth becomes solid very slowly. So crystals are formed in these rocks.
(ii) EXTRUSIVE IGNEOUS ROCKS
When the molten matter comes out on the earth’s surface and becomes solid, the rock thus formed is called Extrusive Igneous Rock. This molten matter can pour out on the earth’s surface either through a volcano or from crack or faults in earth’s crust.
The molten matter becomes solid quickly on the earth’s surface that is why crystals are not formed and if formed, are too small to be seen.
Q.4: Write the characteristics of igneous rocks.
Ans: These rocks came into existence in the beginning. Therefore, these rocks are also called Primary Rocks.
There are no layers in these rocks.
These rocks are hard.
In these rocks, fossils of animals and plants are not found.
Q.5: Write a detailed note on Sedimentary Rocks.
Ans: SEDIMENTARY ROCKS
Sedimentary rocks are formed by the deposition of sediments near or surface of the earth in a layered form. These sediments are comprised of sand, stone and muds etc are carried by wind, river or glacier. These sediments are transported to far of places and deposited slayer by layer. With the passage of time, these layers fix together firmly and a rock is formed. Due to deposition of sediments, this rock is called “Sedimentary Rock”
TYPES OF SEDIMENTARY ROCKS ‘
There are three types of sedimentary rocks according to their formation:
Mechanically formed rocks
Chemically formed rocks.
iii. Organic rocks
MECHANICALLY FORMED ROCKS
Wind, a river and glacier erode the rock in different Ways, transport sediments and deposit them in a layered form. The layers of sediments formed a rock. It is called mechanically formed rock. In Pakistan these rocks are found in northern areas and Potwar Plateau.
CHEMICALLY FORMED ROCKS
Different types of dissolved salts are found in water on the earth’s surface. When this water, evaporates, it leaves behind layers of salts. The rocks which are formed by these layers are called “Chemically Formed Rocks”. Rock salt, gypsum and dolomite are chemically formed rocks.
In Pakistan, these rocks are found in the areas of salt range, Daud Khel, D.G Khan and Dadu.
iii. ORGANIC ROCKS
Organic rocks are formed by the fossils of animals and plants. That is why calcium is found in abundance in these rocks. These rocks are formed both on the ocean floor and the land.
If in organic rocks the fossils of animals are in abundance, then these rocks are called “Calcareous Rock” Calcium is found in abundance in these rocks. Limestone and corals are calcareous rocks. In Pakistan, these rocks are found in areas of salt range and Hazara.
If in organic rocks the fossils of plants are found in abundance, then these rocks are called “Carbonaceous Rocks” Carbon is abundantly found in these rocks. Peat (raw coal) is a carbonaceous rock, In Pakistan, these rocks are found in the areas of north-west Balochistan and southern Sindh.
Q.6: Write the characteristics of sedimentary rocks.
Ans: The characteristics of sedimentary rocks are:
The earth’s surface is formed mostly of sedimentary rocks.
These rocks can be identified easily because of their layered form.
These rocks are mostly used in construction Work.
There are fossils of animals and plants in these rocks.
As compared to other types of rock, these rocks are less hard and weak.
Q.7: Classify rocks and write a detailed on Metamorphic Rocks.
Ans: CLASSIFICATION OF ROCKS
According to formation there are three types, of rocks.
Igneous Rocks 2. Sedimentary Rocks
3.Metamorphic Rocks
TYPES OF IGNEOUS RQCKS
According to their formation, the igneous rocks are of two types i.e
intrusive igneous rocks and extrusive igneous rocks.
IGNEOUS ROCKS
Into the interior of the earth, the temperature increases. It is estimated that the temperature is 5000 centigrade in the centre. Because of high range of temperatures, the minerals are melted and a thick igneous matter magma is formed. Magma is a very hot liquid rock below the earth’s surface. When it pours out on the surface of the earth, it is called “Lava”.
SEDIMENTARY ROCKS
Sedimentary rocks are formed by the deposition of sediments in a layered form, near or on the surface of the earth.
TYPES OF SEDIMENTARY ROCKS
According to their formation, the sedimentary rocks are of three types i.e. mechanically formed rocks, chemically formed rocks and organic rocks.
iii. METAMORPHIC ROCKS
Igneous or sedimentary rocks, which have changed their form with the passage of time owing to extreme heat, high temperature and pressure in the interior of the earth, and are smooth shiny, hard and compact, are called “Metamorphic Rocks”. Slate and marble are Metamorphic Rocks. There are two types of Metamorphic Rocks i.e.
Rocks formed by Thermal metamorphism.
Rocks formed by regional Rocks
Formed by Thermal Metamorphism. When the heat of magma moves passing near or over a rock inside the earth, changes its composition and structure. Thus a new rock is formed, which is called Thermal metamorphism. This process can be understood easily from the following example. Bricks are made from wet clay. The dried bricks are placed in the kiln under fire. The following two changes occur in the bricks by this process. Due to extreme temperature and pressure, the colour of clay bricks change and tiny sediments begin to shine. The bricks becomes hard and compact, same change occurs in the rock by extreme heat. Marble is a metamorphic rocks formed by the alternative of limestone, a sedimentary.
Sandstone is a sedimentary rock which changes its form into Quartzite with the passage of time due to high temperature and pressure. In Pakistan, marble is found in the area of Mullaghori (KPK) and Balochistan.
Rocks formed by Regional Metamorphism
Earthquakes and mountains building, the internal forces of the earth, cause a rock to sink in the earth. Due to the pressure, high temperature and weight of overlying rocks, they become hard and compact. This process is called Regional Metamorphism.
Shale is a sedimentary rock. After being squeezed, it turns into slate.
Slate is a metamorphic rock. In due course of time, it further transforms into Schist.
In Pakistan Metamorphic rock are found in the areas of Abbottabad and Kund.
Q.8: Write the characteristics of metamorphic rock.
Ans.
Metamorphic rocks are formed by alteration of pre-existing rocks.
These are more smooth and shiny.
There are more hard and compact.
In these rocks, fossils of animals and plants are not found.
CH: 5 MAJOR LAND FEATURES
Q.1: Describe the surface of the earth.
Ans: The surface of the earth is wonderfully varied everywhere in the world. There is a variety of landforms on it i.e., mountains, plateaus, plains and deserts. Even the sea floor is comprised of uneven surface.
Q.2: How landforms are formed?
Ans: Landforms are formed by the following two forces:
Internal forces of the earth
External forces of the earth
The function of these forces is:
THE ROLE OF INTERNAL FORCES OF THE EARTH
In the interior of the earth, there are such forces, which ‘sometimes push a part of earth upwards or downwards. These forces make new landforms on the earth’s surface. Due to these forces continents and mountain came into being. Similarly, when the molten matter inside the earth comes out on the earth’s surface and becomes solid. In this way, a variety of landforms come into being i.e, volcanoes and plateaus.
THE ROLE OF EXTERNAL FORCES OF THE EARTH
The external forces of the earth are like a sculptor who works on stone with his tools and carved out different features. In the same way the external forces of the earth which are winds, running water, glaciers and sea waves cave out new features on the newly uplifted part dissected coast lines, valleys, lakes, waterfalls, plateaus, springs and plains are formed by these forces. Landforms are divided into three major types i.e. mountains, plateaus and plains.
Q.3: What are mountains? Write a detailed note on the types of plateaus.
ANS: MOUNTAIN
Mountains are the highest places on the earth and have sloping surface. Their bases are broad in comparison to their tops. About 400 millions years ago, the oldest mountains came into being on the earth, which are called Cale Caledonian Mountains.
TYPES OF MOUNTAINS
There are three types of mountains. They are volcanic mountains, folded mountains and block mountains.
VOLCANIC MOUNTAINS
There is a‘ molten matter moving in the interior of the earth. Sometimes, it comes on the earth’s surface through. fault and cracks in the crust of the earth. It becomes solid in the form of a rock or a mountain, which is called a volcano. It has a narrow passage to the top, which is called vent. Its bottom leads into the interior of the earth. Lava comes out from this vent regularly.
Fuji, yama, Krakatoa, Mayon, Etna and Cotopaxi are volcanoes. The largest ranges of volcanoes stretch around the Pacific Ocean, which is known as “The Ring of Fire”.
FOLDED MOUNTAINS
Most of the mountains are sedimentary rocks. During the mountain building process, when the internal forces put their pressure on these rocks from every side, folds occurred in these rocks. After that the internal forces uplift them in the form of mountains on the surface of the earth. They are called Folded Mountains. Himalayas, alps, Rockies and Andes are ranges of folded mountains.
BLOCK MOUNTAINS
Unequal stress and earthquakes create faults and cracks on the earth’s surface. Sometimes, the internal forces uplift a part of the-earth between these faults which becomes higher from the adjacent parts. This is called Block Mountain. Harz in Germany and Bihar Mountain in India are block mountains. Sometimes a part of the earth sinks between two surrounding parts. It is known as a Rift Valley. Such a rift valley is in East Africa, which is 3000 kms long.
Q.4: How plateau is formed? Also write a note on the types of plateaus.
Ans: PLATEAUS
Plateau is a landform, which is higher like a mountain than the surrounding surface of the earth but has a flat and dissected top like a plain. It is also called “Table Land”
Some plateaus came into being by the uplifting of areas during the mountain building process in past times. While some plateaus came into being by the solidification of lava on the surface of the earth.
TYPES OF PLATEAUS
As per formation and location, there are three types of plateaus.
INTERMONTANE PLATEAU
The plateau situated between high mountains is called “Intermontane plateau”. Tibet and Bolivia are intermontane plateaus which came into being with the creation of mountains.
PIEDMONT PLATEAUS
The plateau which is situated in the foot hills of mountains is called “Piedmont Plateau”. There is a plain or a sea on its other side. Patagonia and Colorado are piedmont plateaus which came into being with the creation of mountains.
CONTINENTAL PLATEAU
The plateau surrounded by plains or a sea is called “Continental Plateau”. It is a vast plateau. Saudi Arabi, Spain and Greenland are such plains.
Q.5: Write a detailed note on the types of plains.
Ans: PLAINS
Large stretches of flat lands are called “Plains”. Their height is upto 1000 feet from the sea level. The height of a plain rises gradually and usually cannot be felt. The areas which were not affected by the internal forces of the earth remained flat as plains. However, some of the plains were formed by erosional and depositional
processes
TYPES OF PLAINS
On the above stated basis, plains are classified into the following two major types
Erosional Plains 2. Depositional Plains
EROSIONAL PLAINS
When a landform emerges on the earth s surface, the external forces, which are heat, ram, wind, a river and a glacier begin to reduce 1ts height by erosion The plains thus formed are called Erosional Plains Some of them are:
KARST PLAINS
Some plains in the fworld “are formed of limestone. These were once highlands which became lowlands due to the dissolution by rainwater, surface water and underground Water.
EOLIAN PLAINS
In areas where the amount of rainfall is very low, wind storms have converted the exposed rocks into flat lands by erosion. Isolated less high column like hills are seen in such plains. These are called “Eolian Plain”.
iii. GLACIAL PLAINS
In ancient times, Russian Federation, Finland, Sweden and Canada were covered with continental glaciers. These huge ice sheets converted them into flat lands by erosion. These are called “Glacial Plains”.
DEPOSITIONAL PLAINS
Most of the plains came into being by the deposition of sediments transported by river, winds and glaciers. These are called “Depositional Plains”. These are:
FLOOD PLAINS
When rivers are flooded, their water begin to flow out of their banks and spread over vast areas of land. When the flood water returns to its channel gradually, it leaves behind layers of fine sand and clay. These smooth plains are called “Flood Plains”. The soil of these plain is very fertile.
COASTAL PLAINS
Coastal Plains are formed in two ways:
Rivers, before falling into the sea leave sand on the beach.
Sea waves also deposit sand on the beach. These are called “Coastal Plains”.
iii. LOESS PLAINS
Some plains of the world came into being by very fine sand deposited by wind, which are called Loess Plains. The largest loess plain of the world is situated in China.
Identification of Major Land Features and Rivers of the World
ACTIVITY
On the world map given on the previous page, major land features and rivers have been shown.
Identify the following rivers on that map and write, in which continent they are situated.
Ans:
Rivers
Continents
Ob, Lina
Europe
Amur, Hwanghe
Asia
Yangtze, Mechong
Asia
Ganges
Asia
Indus
Asia
Tigris, Euphrates
Asia
Congo
Africa
Nile
Africa
Niger
Africa
Volga
Europe
Danube
Europe
Machkenzie
North America
Yukon
North America
Missouri
Africa
Mississippi
North America
Amazon
South America
Parana
South America
Murry and Darling
Australia
CH: 6 LAND FEATURES OF PAKISTAN
Q.1: Write a short note on the land features of Pakistan.
Ans: Pakistan is a country with a variety of land surface. It is not homogenous. There are lofty mountain ranges with peaks covered with snow throughout the year, fertile plains, plateaus, green valley and vast deserts.
Q.2: Write a note on the Northern Mountains of Pakistan.
Ans: This mountain range comprises of the Himalayas and the Karakoram.
THE HIMALAYAS
To the North of Pakistan is a chain of ranges of lofty mountains, which are called the Himalayas. These are divided into three segments which are situated parallel to each other from south east to North West.
SIWALIK HILLS
The Siwalik Hills are located in Islamabad, Muree, Hazara and Abbottabad. The average height of these hills is about 800 metres.
LESSER HIMALAYAS
In the north of Siwalik Hills, the mountains of Azad Kashmir and Pir Panjal are situated. The average height of these mountains is about 400 metres. As the height of s these mountains are lesser than the other segments of the Himalayas, they are called Lesser Himalayas.
iii. GREATER HIMALAYAS
Greater Himalayas are located in the north of Lesser Himalayas. These lofty snow peaked mountains are located in Swat, Kohistan and Gilgit. The average height of these mountains is about 6000 metres. The highest peak of this range is Nanga Parbat. Its height is 8,126 metres.
THE KARAKORAM
In the north of the Greater Himalayas, there is another range of snow peaked mountains, located in Gilgit up to Skardu, which is called Karakoram Range. The peak of K-2, which is 8611metres high is situated on this range. It is the second highest peak in the world. In this range, huge glaciers are found in Siachin, Hispar, Baltoro, Biafo and Batura.
Write a note on North western and western mountains of Pakistan.
Ans. North western and western mountains:
In the west of Pamir Knot, there are three mountain ranges. Their height decreases towards the south. These mountains are:
HINDUKUSH MOUNTAINS
The Hindukush Range lies in the north west of Karakoram Range along the border of Afghanistan. This mountain range stretches from Chitral, Swat and Malakand upto the river Kabul in the south. The highest peak of this range is Tirich Mir. It is about 7690 metres high. These mountains are the source of rain in summer in Pakistan and India.
SUFAID KOH AND WAZIRISTAN HILLS
In the south of Hindukush mountain, from river Kabul to river Kurram along the border of Afghanistan lies the mountain range of Koh-e-Sufaid. These mountains are located in Mohmund and Khyber agency. The valley of Peshawar, Kohat and Bannu are also located in these mountains. The highest peak of this range is Sikeram. This is about 4761 metres high. The famous Khyber Pass is located in Koh-e-Sufaid, which connects Peshawar with Kabul.
In the south of Koh-e-Sufaid, Kohat and Waziristan mountains are located between the river Kurram and river Gomal.
iii. SULEMAN AND KIRTHAR MOUNTAINS
In the south of river Gomal upto river Bolan is located the mountain range, known as Suleman mountains. These mountains are located along the river Indus between Punjab and Balochistan. There are many passes through Suleman mountains which connect Pakistan with Afghanistan. The highest peak of this range is Takht-e-Suleman. Its height is 3487 metres high. In the further south of river, there are Kirthar Mountains between Balochistan and Sindh.
Q.4: Write a note on the plateaus of Pakistan.
The area which consists of ridges, troughs basin plains and dissected plain is known as plateau. There are two plateaus in Pakistan. These are:
POTHWAR PLATEAU
It is situated in the south of Siwalik Hills. To its east is the river Jhelum, to the west river Indus and to its south lies the Salt range. There are some-high and low hills in Pothwar Plateau. It includes the districts of Jhelum, Chakwal, Rawalpindi and Attock. Its height ranges from 300 to 600 metres. River Soan and river Haro are the main rivers. Sakessar, Kalar Kahar and Khabeki are the beautiful places.
BALOCHISTAN PLATEAU
This vast plateau is located in the west of Suleman and Kirthar mountains. Its height increases from 300 to 2000 metres. There are many mountain ranges situated in this plateau. These are:
The coastal and central Makran Mountains
Siahan Mountains
Ras Kho
Chaghai Mountains
Pub Mountains
Toba Kakar Mountain
North Western part of Balochistan is almost dry. In it lies a desert between Chaghai and Siahan Mountain in which there is a salt lake known as “Hamun-e-Mashkhel”. Quetta, Chamman and Ziarat are hill stations where fruit cultivation is abundance. ‘There is no big river in this plateau Zhob, Bolan, Hub, Porali, Hingol and Dasht are the main rivers. This region is rich in minerals and natural gas.
Q.5: Write a detailed note on the Indus Pkain
Ans: PLAINS
Balochistan is a plateau. The most of the areas of Khyber Pukhtoon Khawa and northern areas consist of High Mountains, while Punjab and Sindh have been formed by the deposition of alluvium left by the river Indus and its tributaries. That is why this plain is called “Indus Plain”.
UPPER INDUS PLAIN
This plain is spread in the South of Salt Range and in the East of Suleman Range
and Kirthar Mountain, which is spread to the Arabian Sea. At Mithun Kot all the rivers i.e. Jhelnm, Chenab, Ravi and Sutlej join the river Indus from eastern side one by one. Upto Mithun Kot, the maximum part of Punjab has been formed by the deposition of alluvium left by these rivers. It is called Upper Indus Plain. It is very fertile. Its soil is very favourable for cultivation.
LOWER INDUS PLAIN
The region in the South of Mithun. Kot to Thatta is called the Lower Indus Plain. The deserts of Cholistan and Thar are located in the east of the river Indus. This plain is very fertile and suitable for growing crops except deserts.
DELTAIC INDUS PLAIN
The area from Thatta to the coast of Arabian Sea in the south is called Deltaic Indus Plain. Near Thatta, river Indus starts making Delta and is divided into many branches which afterward fall in the Arabian Sea. It is a swampy area.
Q.6: Write a note on the deserts of Pakistan.
The South Easter part of Pakistan consists of deserts. The following are the main deserts of Pakistan:
THAL
It is located in Punjab. To its north is the Salt Range, in’ the east are rivers Jhelum and Chenab, and to its west flows river Indus. Thal desert stretches over the areas of Mianwali, Khushab, Bhakkar, Lieah and Muzaffargarh.
CHOLISTAN
It is located in the south eastern Punjab and is spread over the areas of Bahawalnagar, Bahawalpur and Rahimyar Khan. To its west are river Sutlej and Indus, While eastern side is bordered by India.
THAR
It is located in the eastern Sindh. In the north it joins Cholistan and Rajasthan desert of India in the east. River Indus flows in its west. Thar Desert stretches over the areas of Ghotki, Sukkur, Khairpur, Sanghar and Tharparker.
KHARAN
It is located in the western Balochistan. Kharan desert stretches over the areas of Chaghai and Kharan. In its north are Chaghai Mountains, in the south Siahan Mountains, in the east Ras Koh and in its west lies Iran.
Q.7: Write a note on the coastal areas of Pakistan.
Ans. The Arabian .Sea is located in the south of Pakistan. The length of the coastal belt along the Arabian Sea is more than 1000 kms long. It is divided into the following two parts.
THE COASTAL BELT OF BALOCHISTAN
This belt is about 700 kms long. The ports of Gawadar, Pasni and Lesbela are located on this belt. The coastal belt of Balochistan is not so vast because it is partly flat and partly mountainous.
THE COASTAL BELT OF SINDH
The coastal belt of Sindh is more than 300 kms long. The ports of Karachi, Bin Qasim and Keti are located on this belt. This belt is flat, that is why it is more vast than the coastal Belt of Balochistan.
CH: 7 WORLD POPULATION
1: Write a note on the distribution of population of the world.
Ans: The population of the world is about 6.8 billion. But the distribution of populatin is not uniform. Some areas of the world are thickly populated, some thinly or least populated and some are moderately populated.
The difference of world population in different continents is as under.
Continent
Population (Million)
Percentage
Asia
4040
60.70
Africa
994
14.57
Europe (Including Russia)
738
1082
North America
528
7.74
South America
385
5.64
Australia
36
0.53
Q.2: Write a brief note on the density of population in the world.
Ans: DEFINITION OF DENSITY OF PUPULATION
The average number of person living per square kilometer is called density of population. It is calculated by dividing the total area by the number of persons living there.
DENSITY OF POPULATION OF THE WORLD
The density of the world population is as under:
World Population = 6.8 billion
Area on the earth’s surface = 148 million square km
Density of Population = 46 person per sq. km
It means that density of population in the world per square kilometer of land.
Q.3: Write a detailed note on the high density population areas of the world.
Ans: HIGH DENSITY POPULATION AREAS
The average density of world population is 46 persons per square kilometer. But in some areas of the world the density is about thousands of people per square kilometer, which is as under:
EAST, SOUTHEAST AND SOUTH ASIA
The countries East, Southeast and South Asia like China, Japan, Indonesia, Philippines, Vietnam, India, Pakistan and Bangladesh are densely populated.
REASONS OF HIGH DENSITY
The main reasons of high density of population of these countries are their fertile river valleys and moderate climate and suitable atmosphere.
WESTERN AND CENTRAL EUROPE
The counties of Western and Central Europe like France, Belgium, Holland, Germany, Czech Republic and Australia are very densely populated.
REASONS OF HIGH DENSITY
The main reasons of high density of these countries is their suitable climate and industrial development.
iii. NORTH-EASTERN AND SOUTH-EASTERN AMERICA
The North-Eastern part of the United States of America and the South-Eastern part of Canada is very densely populated.
REASON OF THE HIGH DENSITY
The main reasons of high density of these areas are their industrial development and moderate climate of coastal areas.
Q.4: Write a note on the moderate density population areas of the world.
Ans: MODERATE DENSITY POPULATION AREAS
The moderate density population areas consist of grasslands of the world.
Here, population is scattered over a large area. There are 10 to 50 persons living per square kilometre.
NAME OF GRASSLANDS
These grasslands of the world are known by the following different names:
Steppes of Asia and Europe
Prairies of North America
Pampas of South America
Savannas of Africa
Downs of Australia
These areas of the world are famous for agriculture.
REASONS OF MODERATE DENSITY
Due to shortage of industries, these areas are moderately populated.
Q.5: Write a note on the low density population areas of the world.
Ans: Extreme cold, hot, rainy and dry regions of the World are the least populated, because of harsh climate. The density of population in these areas is less than 10 persons per square kilometre. These areas consist of :
Polar areas
Snow peaked mountains like Himalayas, Alps, Rockies and Andes
Equatorial Rain forests
Deserts like Sahara, Kalahari, Atacama, Arab and Rajasthan etc.
Reasons of Low Density of Population
The harsh climate and unsuitable conditions of these areas do not allow habitation there.
Q.6: Write a note on the structure of population
Ans: DEFINITION OF POPULATION STRUCTURE
Structure of population is the study of both sex and age together.
DIVISION OF POPULATION
According to sex, population is divided into three groups. These are:
(i) Male population (ii) Female population
According to age, population is divided into the following three groups:
(i) Children upto 15 years (ii) Adult 15 to 60 years
(iii) Aged more than 60 years
Usually, sex and age are studied together, that is called Sex-Age structure. It tells us about:
The number of males and females in the population
The percentage of children, adult and aged persons in the population.
The sex-age structure in more developed countries (MDCs) is different from the less developed countries (LDCs)
Country
Population(Million)
Sex
Age
Male%
Female%
Children
Adults
Aged
Japan
128
43
57
15
53
32
Germany
82
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