Environment

 The place, people, things and nature that surround any living organism is called environment.
It is a combination of natural and human made phenomena. While the natural environment
refers to both biotic and abiotic conditions existing on the earth, environment reveals the
activities, creations and interactions among human beings.
 Lithosphere is the solid crust or the hard top layer of the earth. It is made up of rocks and
minerals and covered by a thin layer of soil. It is an irregular surface with various landforms
such as mountains, plateaus, plains, valleys, etc. Landforms are found over the continents and
also on the ocean floors.
 The domain of water is referred to as hydrosphere. It comprises various sources of water and
different types of water bodies like rivers, lakes, seas, oceans, etc. It is essential for all living
organisms.
 The atmosphere is the thin layer of air that surrounds the earth. The gravitational force of the
earth holds the atmosphere around it. It protects us from the harmful rays and scorching heat
of the sun. It consists of a number of gases, dust and water vapor. The changes in the
atmosphere produce changes in the weather and climate.
 Plant and animal kingdom together make biosphere or the living world. It is a narrow zone of
the earth where land, water and air interact with each other to support life.
 On 5 June every year the World Environment Day is celebrated.

Inside Our Earth

 The uppermost layer over the earth’s surface is called the crust. It is the thinnest of all the
layers. It is about 35 km. on the continental masses and only 5 km. on the ocean floors.
 The main mineral constituents of the continental mass are silica and alumina. It is thus called
sial (si-silica and al-alumina). The oceanic crust mainly consists of silica and magnesium; it is
therefore called sima (si-silica and ma-magnesium).
 Just beneath the crust is the mantle which extends up to a depth of 2900 km. below the crust.
 The innermost layer is the core with a radius of about 3500 km. It is mainly made up of nickel
and iron and is called nife (ni-nickel and fe-iron). The central core has very high temperature
and pressure.
 The deepest mine in the world, is in South Africa. It is about 4 km. deep. In search for oil
engineers have dug a hole about 6 km. deep.
 The crust forms only 1 per cent of the volume of the earth, 84 per cent consists of the mantle
and 15 per cent makes the core. The radius of the earth is 6371 km.
 Any natural mass of mineral matter that makes up the earth’s crust is called a rock. There are
three major types of rocks: igneous rocks, sedimentary rocks and metamorphic rocks.
 Igneous: Latin word Ignis meaning fire. When the molten magma cools, it becomes solid.
Rocks thus formed are called igneous rocks. They are also called primary rocks. There are two
types of igneous rocks: intrusive rocks and extrusive rocks.
 Lava is actually fiery red molten magma coming out from the interior of the earth on its
surface. When this molten lava comes on the earth’s surface, it rapidly cools down and
becomes solid. Rocks formed in such a way on the crust are called extrusive igneous rocks.
They have a very fine grained structure. For example, basalt. The Deccan plateau is made up
of basalt rocks. Sometimes the molten magma cools down deep inside the earth’s crust. Solid
rocks so formed are called intrusive igneous rocks. Since they cool down slowly they form
large grains. Granite is an example of such a rock.
 Sedimentary: Latin word sedimentum meaning settle down. Rocks roll down, crack, and hit
each other and are broken down into small fragments. These smaller particles are called
sediments. These sediments are transported and deposited by wind, water, etc. These loose
sediments are compressed and hardened to form layers of rocks. These types of rocks are
called sedimentary rocks. For example, sandstone is made from grains of sand. These rocks
may also contain fossils of plants, animals and other micro-organisms that once lived on them.
 The remains of the dead plants and animals trapped in the layers of rocks are called fossils.
 Igneous and sedimentary rocks can change into metamorphic rocks under great heat and
pressure. For example, clay changes into slate and limestone into marble.
 One type of rock changes to another type under certain conditions in acyclic manner. This
process of transformation of the rock from one to another is known as the rock cycle.
 When the molten magma cools; it solidifies to become igneous rock. These igneous rocks are
broken down into small particles that are transported and deposited to form sedimentary
rocks. When the igneous and sedimentary rocks are subjected to heat and pressure they
change into metamorphic rocks. The metamorphic rocks which are still under great heat and
pressure melt down to form molten magma. This molten magma again can cool down and
solidify into igneous rocks.
 Minerals are naturally occurring substances which have certain physical properties and
definite chemical composition. Minerals are very important to humankind. Some are used as
fuels. For example, coal, natural gas and petroleum. They are also used in industries – iron,
aluminum, gold, uranium, etc, in medicine, in fertilizers, etc.

Our Changing Earth

 The lithosphere is broken into a number of plates known as the Lithospheric plates. These
plates move around very slowly – just a few millimeters each year. This is because of the
movement of the molten magma inside the earth.
 The movement of these plates causes changes on the surface of the earth. The earth
movements are divided on the basis of the forces which cause them. The forces which act in
the interior of the earth are called as Endogenic forces and the forces that work on the surface
of the earth are called as Exogenic forces.
 Endogenic forces sometimes produce sudden movements and at the other times produce slow
movements. Sudden movements like earthquakes and volcanoes cause mass destruction over
the surface of the earth.
 A volcano is a vent (opening) in the earth’s crust through which molten material erupts
suddenly.
 Similarly, when the Lithospheric plates move, the surface of the earth vibrates. The vibrations
can travel all round the earth. These vibrations are called earthquakes. The place in the crust
where the movement starts is called the focus. The place on the surface above the focus is
called the epicenter. Vibrations travel outwards from the epicenter as waves. Greatest
damage is usually closest to the epicenter and the strength of the earthquake decreases away
from the centre.
 There are three types of earthquake waves: P waves or longitudinal waves; S waves or
transverse waves; L waves or surface waves.

 An earthquake is measured with a machine called a seismograph. The magnitude of the

earthquake is measured on the Richter scale.
 The landscape is being continuously worn away by two processes – weathering and erosion.
Weathering is the breaking up of the rocks on the earth’s surface. Erosion is the wearing away
of the landscape by different agents like water, wind and ice. The eroded material is carried
away or transported by water, wind, etc. and eventually deposited. This process of erosion
and deposition create different landforms on the surface of the earth.
 When the river tumbles at steep angle over very hard rocks or down a steep valley side it
forms a waterfall. As the river enters the plain it twists and turns forming large bends known
as meanders. Due to continuous erosion and deposition along the sides of the meander, the
 ends of the meander loop come closer and closer. In due course of time the meander loop cuts
off from the river and forms a cut-off lake, also called an ox-bow lake.
 As it floods, it deposits layers of fine soil and other material called sediments along its banks.
This leads to the formation of a flat fertile flood plain. The raised banks are called levees.
 As the river approaches the sea, the speed of the flowing water decreases and the river begins
to break up into a number of streams called distributaries. The river becomes so slow that it
begins to deposit its load. Each distributary forms its own mouth. The collection of sediments
from all the mouths forms a delta.
 Sea waves continuously strike at the rocks. Cracks develop. Overtime they become larger and
wider. Thus, hollow like caves are formed on the rocks. They are called sea caves. As these
cavities become bigger and bigger only the roof of the caves remain, thus forming sea arches.
Further, erosion breaks the roof and only walls are left. These walls like features are called
stacks. The steep rocky coast rising almost vertically above sea water is called sea cliff. The sea
waves deposit sediments along the shores forming beaches.
 Glaciers are “rivers of ice” which too erode the landscape by bulldozing soil and stones to
expose the solid rock below. Glaciers carve out deep hollows there. As the ice melts they get
filled up with water and become beautiful lakes in the mountains. The material carried by the
glacier such as rocks big and small, sand and silt gets deposited. These deposits form glacial
moraines.
 An active agent of erosion and deposition in the deserts is wind. In deserts you can see rocks
in the shape of a mushroom, commonly called mushroom rocks. Winds erode the lower
section of the rock more than the upper part. Therefore, such rocks have narrower base and
wider top. When the wind blows, it lifts and transports sand from one place to another. When
it stops blowing the sand falls and gets deposited in low hill – like structures. These are called
sand dunes. When the grains of sand are very fine and light, the wind can carry it over very
long distances. When such sand is deposited in large areas, it is called loess. Large deposits of
loess is found in China.

Air
 Nitrogen (78%) and oxygen (21%) are two gases which make up the bulk of the atmosphere.
Carbon dioxide (0.03%), argon (0.93%) helium, ozone and hydrogen (0.04%) are found in lesser
quantities. Apart from these gases, tiny dust particles are also present in the air.
 Plants need nitrogen for their survival. They cannot take nitrogen directly from the air.
Bacteria that live in the soil and roots of some plants take nitrogen from the air and change its
form so that plants can use it.
 Humans and animals take oxygen from the air as they breathe. Green plants produce oxygen
during photosynthesis. In this way oxygen content in the air remains constant. If we cut trees
then this balance gets disturbed.
 Green plants use carbon dioxide to make their food and release oxygen. Humans or animals
release carbon dioxide. The amount of carbon dioxide released by humans or animals seems
to be equal to the amount used by the plants which make a perfect balance.
 The balance is upset by burning of fuels, such as coal and oil. They add billions of tons of
carbon dioxide into the atmosphere each year. As a result, the increased volume of carbon
dioxide is affecting the earth’s weather and climate.
 Our atmosphere is divided into five layers starting from the earth’s surface. These are
Troposphere, Stratosphere, Mesosphere, Thermosphere and Exosphere.
 Troposphere: This layer is the most important layer of the atmosphere. Its average height is 13
km. The air we breathe exists here. Almost all the weather phenomena like rainfall, fog and
hailstorm occur in this layer.
 Stratosphere: It extends up to a height of 50 km. This layer is almost free from clouds and
associated weather phenomenon, making conditions most ideal for flying aero planes. One
important feature of stratosphere is that it contains a layer of ozone gas.
 Mesosphere: This is the third layer of the atmosphere. It lies above the stratosphere. It
extends up to the height of 80 km. Meteorites burn up in this layer on entering from the
space.
 Thermosphere: In thermosphere temperature rises very rapidly with increasing height.
Ionosphere is a part of this layer. It extends between 80-400 km. This layer helps in radio
transmission. In fact, radio waves transmitted from the earth are reflected back to the earth
by this layer.
 Exosphere: The upper most layer of the atmosphere is known as exosphere. This layer has
very thin air. Light gases like helium and hydrogen float into the space from here.
 The average weather condition of a place for a longer period of time represents the climate of
a place.
 An important factor that influences the distribution of temperature is insolation. Insolation is
the incoming solar energy intercepted by the earth. The amount of insolation decreases from
the equator towards the poles. The temperature decreases in the same manner.
 Temperature in cities is much higher than that of villages. The concrete and metals in buildings
and the asphalt of roads get heated up during the day. This heat is released during the night.
Also, the crowded high rise buildings of the cities trap the warm air and thus raise the
temperature of the cities.
 The air pressure is highest at sea level and decreases with height. Horizontally the distribution
of air pressure is influenced by temperature of air at a given place. In areas where
temperature is high the air gets heated and rises. This creates a low-pressure area. Low
pressure is associated with cloudy skies and wet weather.
 In areas having lower temperature, the air is cold. It is therefore heavy. Heavy air sinks and
creates a high pressure area. High pressure is associated with clear and sunny skies.
 The movement of air from high pressure area to low pressure areas is called wind.
 Types of Winds: -
 o Permanent winds – The trade winds, westerlies and easterlies are the permanent
winds. These blow constantly throughout the year in a particular direction.
o Seasonal winds – These winds change their direction in different seasons. For example
monsoons in India.
o Local winds – These blow only during a particular period of the day or year in a small
area. For example, land and sea breeze, the loo.

 When water evaporates from land and different water bodies, it becomes water vapour.
Moisture in the air at any time is known as humidity. When the air is full of water vapour we
call it a humid day. As the air gets warmer, its capacity to hold the water vapour increases and
so it becomes more and more humid. On a humid day, clothes take longer to dry and sweat
from our body does not evaporate easily, making us feel very uncomfortable.
 When the water vapour rises, it starts cooling. The water vapour condenses causing formation
of droplets of water. Clouds are just masses of such water droplets. When these droplets of
water become too heavy to float in air, then they come down as precipitation.
 Precipitation that comes down to the earth in liquid form is called rain. Most of the
groundwater comes from rainwater. Plants help preserve water. When trees on hill sides are
cut, rainwater flows down the bare mountains and can cause flooding of low lying areas.
 On the basis of mechanism, there are three types of rainfall: the convectional rainfall, the
orographic (relief) rainfall and the cyclonic rainfall.

Water
 The sun’s heat causes evaporation of water into vapor. When the water vapor cools down, it
condenses and forms clouds. From there it may fall on the land or sea in the form of rain,
snow or sleet. The process by which water continually changes its form and circulates
between oceans, atmosphere and land is known as the water cycle.
 The major sources of fresh water are the rivers, ponds, springs and glaciers. The ocean bodies
and the seas contain salty water. The water of the oceans is salty or saline as it contains large
amount of dissolved salts. Most of the salt is sodium chloride or the common table salt that
you eat.
 Dead Sea in Israel has salinity of 340 grams per litre of water. Swimmers can float in it because
the increased salt content makes it dense. Salinity is the amount of salt in grams present in
1000 grams of water. The average salinity of the oceans is 35 parts per thousand.
 March 22 iscelebrated as World Water Day when the need to conserve water is reinforced
indifferent ways.
 When the water on the surface of the ocean rises and falls alternately, they are called waves.
Waves are formed when winds scrape across the ocean surface. The stronger the wind blows,
the bigger the wave becomes.
 During a storm, the winds blowing at very high speed form huge waves. These may cause
tremendous destruction. An earthquake, a volcanic eruption or underwater landslides can
shift large amounts of ocean water. As a result a huge tidal wave called tsunami, that may be
as high as 15m., is formed. The largest tsunami ever measured was 150m. High. These waves
travel at a speed of more than 700 km. per hour. The tsunami of 2004 caused wide spread
damage in the coastal areas of India. The Indira point in the Andaman and Nicobar islands got
submerged after the tsunami.
 The rhythmic rise and fall of ocean water twice in a day is called a tide. It is high tide when
water covers much of the shore by rising to its highest level. It is low tide when water falls to
its lowest level and recedes from the shore.
 The strong gravitational pull exerted by the sun and the moon on the earth’s surface causes
the tides. The water of the earth closer to the moon gets pulled under the influence of the
moon’s gravitational force and causes high tide. During the full moon and new moon days, the
sun, the moon and the earth are in the same line and the tides are highest. These tides are
called spring tides. But when the moon is in its first and last quarter, the ocean waters get
drawn in diagonally opposite directions by the gravitational pull of sun and moon resulting in
low tides. These tides are called neap tides.
 High tides help in navigation. They raise the water level close to the shores. This helps the
ships to arrive at the harbour more easily. The high tides also help in fishing. Many more fish
come closer to the shore during the high tide. This enables fishermen to get a plentiful catch.
The rise and fall of water due to tides is being used to generate electricity in some places.
 Ocean currents are streams of water flowing constantly on the ocean surface in definite
directions. The ocean currents may be warm or cold. Generally, the warm ocean currents
originate near the equator and move towards the poles. The cold currents carry water from
polar or higher latitudes to tropical or lower latitudes. The Labrador Ocean current is cold
current while the Gulf Stream is a warm current. The ocean current influence the temperature
conditions of the area. Warm currents bring about warm temperature over land surface. The
areas where the warm and cold currents meet provide the best fishing grounds of the world.
Seas around Japan and the eastern coast of North America are such examples. The areas
where a warm and cold current meet also experience foggy weather making it difficult for
navigation.
 Natural Vegetation and Wildlife
 With the change in height, the climate changes and that changes natural vegetation. The
growth of vegetation depends on temperature and moisture. It also depends on factors like
slope and thickness of soil.
 Natural vegetation is generally classified in to three broad categories as follows:
o Forests: Which grow where temperature and rainfall are plentiful to support a tree
cover. Depending upon these factors, dense and open forests are grown.
o Grasslands: Which grow in the region of moderate rain.
o Shrubs: Thorny shrubs and scrubs grow in the dry region.
 Tropical Evergreen Forests
o These forests are also called tropical rain forests. These thick forests occur in the
regions near the equator and close to the tropics. These regions are hot and receive
heavy rainfall throughout the year. As there is no particular dry season, the trees do
not shed their leaves altogether. This is the reason they are called evergreen.
o The thick canopies of the closely spaced trees do not allow the sunlight to penetrate
inside the forest even in the day time. Hardwood trees like rosewood, ebony, and
mahogany are common here.
o The tropical evergreen forest in Brazil is so enormous that it is like the lungs of the
earth.
o Anaconda, one of the world’s largest snakes is found in the tropical rainforest. It can
kill and eat a large animal such as a crocodile.
 Tropical Deciduous Forests
o Tropical deciduous are the monsoon forests found in the large part of India, northern
Australia and in Central America. These regions experience seasonal changes. Trees
shed their leaves in the dry season to conserve water. The hardwood trees found in
these forests are sal, teak, neem and shisham. Hardwood trees are extremely useful
for making furniture, transport and constructional materials. Tigers, lions, elephants,
langoors and monkeys are the common animals of these regions.
 Temperate Evergreen Forests
o The temperate evergreen forests are located in the mid-latitudinal coastal region.
They are commonly found along the eastern margin of the continents, e.g., in south
east USA, South China and in South East Brazil. They comprise both hard and soft
wood trees like oak, pine, eucalyptus, etc.
 Temperate Deciduous Forests
o As we go towards higher latitudes, there are more temperate deciduous forests. These
are found in the north eastern part of USA, China, New Zealand, and Chile and also
found in the coastal regions of Western Europe. They shed their leaves in the dry
season. The common trees are oak, ash, beech, etc. Deer, foxes, wolves are the
animals commonly found. Birds like pheasants, monals are also found here.
 Mediterranean Vegetation
 o The west and south west margins of the continents are different. They have
Mediterranean vegetation. It is mostly found in the areas around the Mediterranean
Sea in Europe, Africa and Asia, hence the name. This kind of vegetation is also found
outside the actual Mediterranean region in California in the USA, south West Africa,
south western South America and South west Australia. These regions are marked for
hot dry summers and mild rainy winters. Citrus fruits such as oranges, figs, olives and
grapes are commonly cultivated here because people have removed the natural
vegetation in order to cultivate what they want to. There isn’t much wildlife here.
o Mediterranean trees adapt themselves to dry summers with the help of their thick
barks and wax coated leaves which help them reduce transpiration.
o Mediterranean regions are known as ‘Orchards of the world’ for their fruit cultivation.
 Coniferous Forests
o In the higher latitudes (50° – 70°) of Northern hemisphere the spectacular Coniferous
forests are found. These are also called as Taiga. These forests are also seen in the
higher altitudes. They are found in the Himalayas. They are tall, softwood evergreen
trees. The woods of these trees are very useful for making pulp, which is used for
manufacturing paper and newsprint. Match boxes and packing boxes are also made
from softwood. Chir, pine, cedar is the important variety of trees in these forests.
Silver fox, mink, polar bear are the common animals found here.
 Tropical grasslands: These occur on either side of the equator and extend till the tropics. This
vegetation grows in the areas of moderate to low amount of rainfall. The grass can grow very
tall, about3 to 4 metres in height. Savannah grasslands of Africa are of this type. Elephants,
zebras, giraffes, deer, leopards are common in tropical grasslands.
 Temperate grasslands: These are found in the mid-latitudinal zones and in the interior part of
the continents. Usually, grass here is short and nutritious. Wild buffaloes, bisons, antilopes are
common in the temperate region.
 Thorny bushes: These are found in the dry desert like regions. Tropical deserts are located on
the western margins of the continents. The vegetation cover is scarce here because of scanty
rain and scorching heat.
 If you reach the polar region you will find the place extremely cold. The growth of natural
vegetation is very limited here. Only mosses, lichens and very small shrubs are found here. It
grows during the very short summer. This is called Tundra type of vegetation. This vegetation
is found in the polar areas of Europe, Asia and North America. The animals have thick fur and
thick skin to protect themselves from the cold climatic conditions. Seal, walruses, musk-oxen,
Arctic owl, Polar bear and snow foxes are some of the animals found here.
 Grasslands are known by different names in different regions.
o Tropical Grasslands
 East Africa-Savanna
 Brazil-Campos
 Venezuela-Llanos
o Temperate Grasslands
  Argentina- Pampas
 N. America- Prairie
 S. Africa- Veld
 C. Asia- Steppe
 Australia- Down

Human Environment – Settlement, Transport

and Communication
 Settlements are places where people build their homes. The place where a building or a
settlement develops is called its site.
 Settlements can be permanent or temporary. Settlements which are occupied for a short time
are called temporary settlements. The people living in deep forests, hot and cold deserts and
mountains often dwell in such temporary settlements. They practice hunting, gathering,
shifting cultivation and transhumance. However more and more settlements today are
permanent settlements. In these settlements, people build homes to live in.
 Transhumance: It is a seasonal movement of people. People who rear animals move in search
of new pastures according to changes in seasons.
 A compact settlement is a closely built area of dwellings, wherever flat land is available. In a
scattered settlement dwellings are spaced over an extensive area. This type of settlement is
mostly found in hilly tracts, thick forests, and regions of extreme climate.
 In regions of heavy rainfall, they have slanting roofs. Places where water accumulates in the
rainy season the houses are constructed on a raised platform or stilts.
 Thick mud walled houses with thatched roofs are very common in areas of hot climate. Local
materials like stones, mud, clay, straw etc are used to construct houses.
 The most commonly used means of transport especially for short distances are roads. They
can be metalled (pucca) and unmetalled (kutcha). The plains have a dense network of roads.
Roads have also been build in terrains like deserts, forests and even high mountains. Manali-
Leh highway in the Himalayan Mountains is one of the highest roadways in the world. Roads
built underground are called subways/ under paths. Flyovers are built over raised structures.
 The invention of the steam engine and the Industrial Revolution helped in speedy
development of rail transport. Diesel and electric engines have largely replaced the steam
engines. In places super fast trains have been introduced to make the journey faster. The
railway network is well developed over the plain areas. Advanced technological skills have
enabled laying of railway lines in difficult mountain terrains also. But these are much fewer in
number. Indian railway network is well developed. It is the largest in Asia.
 The Trans-Siberian Railway is the longest railway system connecting St. Petersburg in Western
Russia to Vladivostok on the Pacific coast.
 Waterways are the cheapest for carrying heavy and bulky goods over long distances. They are
mainly of two types – inland waterways and sea routes.
 Some of the important inland waterways are the Ganga-Brahmaputra river system, the Great
Lakes in North America and the river Nile in Africa.
 Sea routes and oceanic routes are mostly used for transporting merchandise and goods from
one country to another. These routes are connected with the ports. Some of the important
ports of the world are Singapore and Mumbai in Asia, New York, Los Angeles in North
America, Rio de Janerio in South America, Durban and Cape Town in Africa, Sydney in
Australia, London and Rotterdam in Europe.
 Airways are the fastest way of transport developed in the early twentieth century. It is also
the most expensive due to high cost of fuels. Air traffic is adversely affected by bad weather
like fog and storms. It is the only mode of transport to reach the most remote and distant
areas especially where there are no roads and railways. Helicopters are extremely useful in
most inaccessible areas and in time of calamities for rescuing people and distributing food,
water, clothes and medicines.
 Communication is the process of conveying messages to others. With the development of
technology humans have devised new and fast modes of communication.
 Through newspapers, radio and television we can communicate with a large number of
people. They are therefore called mass media. The satellites have made communication even
faster. Satellites have helped in oil exploration, survey of forest, underground water, mineral
wealth, weather forecast and disaster warning.

Human Environment Interactions- Tropical and

Subtropical regions
 The tropical region lies very close to the equator; between 10°N and 10°S. So, it is referred to
as the equatorial region. The river Amazon flows through this region. It flows from the
mountains to the west and reaches the Atlantic Ocean to the east.
 The place where a river flows into another body of water is called the river’s mouth.
Numerous tributaries join the Amazon River to form the Amazon basin. The river basin drains
portions of Brazil, parts of Peru, Bolivia, Ecuador, Columbia and a small part of Venezuela.
 The Amazon Basin stretches directly on the equator and is characterized by hot and wet
climate throughout the year. Both day and nights are almost equally hot and humid. The skin
feels sticky. It rains almost every day, that too without much warning. The day temperatures
are high with very high humidity. At night the temperature goes down but the humidity
remains high.
 As it rains heavily in this region, thick forests grow. The forests are in fact so thick that the
dense “roof” created by leaves and branches does not allow the sunlight to reach the ground.
The ground remains dark and damp. Only shade tolerant vegetation may grow here. Orchids,
bromeliads grow as plant parasites.
 The rainforest is rich in fauna. Birds such as toucans, humming birds, bird of paradise with
their brilliantly colored plumage, oversized bills for eating make them different from birds we
 commonly see in India. These birds also make loud sounds in the forests. Animals like
monkeys, sloth and ant-eating tapirs are found here. Various species of reptiles and snakes
also thrive in these jungles. Crocodiles, snakes, pythons abound. Anaconda and boa
constrictor are some of the species. Besides, the basin is home to thousands of species of
insects. Several species of fishes including the flesh-eating Piranha fish is also found in the
river. This basin is thus extraordinarily rich in the variety of life found there.
 People grow most of their food in small areas after clearing some trees in the forest. While
men hunt and fish along the rivers, women take care of the crops. They mainly grow tapioca,
pineapple and sweet potato. As hunting and fishing are uncertain it is the women who keep
their families alive by feeding them the vegetables they grow. They practice “slash and burn
agriculture”. The staple food is manioc, also known as cassava that grows under the ground
like the potato. They also eat queen ants and egg sacs. Cash crops like coffee, maize and cocoa
are also grown.
 The developmental activities are leading to the gradual destruction of the biologically diverse
rainforests. It is estimated that a large area of the rainforest has been disappearing annually in
the Amazon basin. You can see that this destruction of forests has a much wider implication.
The topsoil is washed away as the rains fall and the lush forest turns into a barren landscape.
 The tributaries of rivers Ganga and Brahmaputra together form the Ganga-Brahmaputra basin
in the Indian subcontinent. The basin lies in the sub-tropical region that is situated between
10°N to 30°N latitudes. The tributaries of the River Ganga like the Ghaghra, the Son, the
Chambal, the Gandak, the Kosi and the tributaries of Brahmaputra drain it.
 Himalayas and the Sundarbans delta are the main features of this basin. Ox-bow lakes dot the
plain area. The area is dominated by monsoon climate. The monsoon brings rains from mid-
June to mid-September. The summers are hot and the winters cool.
 The plain area provides the most suitable land for human habitation. The soil is fertile.
Agriculture is the main occupation of the people where flat land is available to grow crops.
The density of population of the plains is very high. The main crop is paddy. Since cultivation
of paddy requires sufficient water, it is grown in the areas where the amount of rainfall is
high.
 Wheat, maize, sorghum, gram and millets are the other crops that are grown. Cash crops like
sugarcane and jute are also grown. Banana plantations are seen in some areas of the plain. In
West Bengal and Assam tea is grown in plantations. Silk is produced through the cultivation of
silk worms in parts of Bihar and Assam. In the mountains and hills, where the slopes are
gentle, crops are grown on terraces.
 In the Ganga and Brahmaputra plain tropical deciduous trees grow, along with teak, sal and
peepal. Thick bamboo groves are common in the Brahmaputra plain. The delta area is covered
with the mangrove forests. In parts of Uttarakhand, Sikkim and Arunachal Pradesh, coniferous
trees like pine, deodar and fir can be seen because the climate is cool and the slopes are
steep.
 Elephants, tigers, deer and monkeys are common. The one-horned rhinoceros is found in the
Brahmaputra plain. In the delta area, Bengal tiger, crocodiles and alligator are found. Aquatic
 life abounds in the fresh river waters, the lakes and the Bay of Bengal Sea. The most popular
varieties of the fish are the rohu, catla and hilsa.
 In the fresh waters of River Ganga and River Brahmaputra, a variety of dolphin locally called
Susu (also called blind dolphin) is found. The presence of Susu is an indication of the health of
the river. The untreated industrial and urban wastes with high amount of chemicals are killing
this species.
 The Ganga-Brahmaputra plain has several big towns and cities. The cities of Allahabad,
Kanpur, Varanasi, Lucknow, Patna and Kolkata all with the population of more than ten lakhs
are located along the River Ganga. The waste water from these towns and industries is
discharged into the rivers. This leads to the pollution of the rivers.
 All the four ways of transport are well developed in the Ganga-Brahmaputra basin. In the
plain areas the roadways and railways transport the people from one place to another. The
waterways, is an effective means of transport particularly along the rivers. Kolkata is an
important port on the River Hooghly. The plain area also has a large number of airports.
 Tourism is another important activity of the basin. Taj Mahal on the banks of River Yamuna in
Agra, Allahabad on the confluence of the Rivers Ganga and Yamuna, Buddhists stupas in Uttar
Pradesh and Bihar, Lucknow with its Imambara, Assam with Kaziranga and Manas with wild
life sanctuaries and Arunachal Pradesh with a distinct tribal culture are some of the places
worth a visit.

Life in the Deserts

 It is an arid region characterized by extremely high or low temperatures and has scarce
vegetation.
 Sahara is the world’s largest desert. It has an area of around 8.54 million sq. km. The Sahara
desert touches eleven countries. These are Algeria, Chad, Egypt, Libya, Mali, Mauritania,
Morocco, Niger, Sudan, Tunisia and Western Sahara.
 The climate of the Sahara desert is scorching hot and parch dry. It has a short rainy season.
The sky is cloudless and clear. Here, the moisture evaporates faster than it accumulates. Days
are unbelievably hot. The temperatures during the day may soar as high as50°C, heating up
the sand and the bare rocks, which in turn radiates heat making everything around hot. The
nights may be freezing cold with temperatures nearing zero degrees.
 Vegetation in the Sahara desert includes cactus, date palms and acacia. In some places there is
oasis – green islands with date palms surrounding them. Camels, hyenas, jackals, foxes,
scorpions, many varieties of snakes and lizards are the prominent animal species living there.
 The Sahara desert despite its harsh climate has been in habited by various groups of people,
who pursue different activities. Among them are the Bedouins and Tuaregs. These groups are
nomadic tribes rearing livestock such as goats, sheep, camels and horses. These animals
provide them with milk, hides from which they make leather for belts, slippers, water bottles;
hair is used for mats, carpets, clothes and blankets. They wear heavy robes as protection
against dust storms and hot winds.
 The oasis in the Sahara and the Nile Valley in Egypt supports settled population. Since water is
available, the people grow date palms. Crops such as rice, wheat, barley and beans are also
grown. Egyptian cotton, famous worldwide is grown in Egypt.
 The discovery of oil – a product in great demand throughout the world, in Algeria, Libya and
Egypt is constantly transforming the Sahara desert. Other minerals of importance that are
found in the area include iron, phosphorus, manganese and uranium.
 Depressions are formed when the wind blows away the sands. In the depressions where
underground water reaches the surface, an oasis is formed. These areas are fertile .People
may settle around these water bodies and grow date palms and other crops. Sometimes the
oasis may be abnormally large. Tafilalet Oasis in Morocco is a large oasis with an area of about
13,000 sq.km.
 Ladakh is a cold desert lying in the Great Himalayas, on the eastern side of Jammu and
Kashmir. The Karakoram Range in the north and the Zanskar Mountains in the south enclose
it. Several rivers flow through Ladakh, Indus being the most important among them. The rivers
form deep valleys and gorges. Several glaciers are found in Ladakh, for example the Gangri
glacier.
 Ladakh is also known as Khapa-chan which means snow land.
 The altitude in Ladakh varies from about 3000m in Kargil to more than 8,000m in the
Karakoram. Due to its high altitude; the climate is extremely cold and dry. The air at this
altitude is so thin that the heat of the sun can be felt intensely. The day temperatures in
summer are just above zero degree and the night temperatures well below –30°C. It is freezing
cold in the winters when the temperatures may remain below –40°C for most of the time. As
it lies in the rain shadow of the Himalayas, there is little rainfall, as low as 10 cm every year.
The area experiences freezing winds and burning hot sunlight. You will be surprised to know
that if you sit in the sun with your feet in the shade, you may suffer from both sunstroke and
frost bite at the same time.
 There are scanty patches of grasses and shrubs for animals to graze. Groves of willows and
poplars are seen in the valleys. During the summers, fruit trees such as apples, apricots and
walnuts bloom. Several species of birds are sighted in Ladakh. Robins, redstarts, Tibetan
snowcock, raven and hoopoe are common. Some of these are migratory birds. The animals of
Ladakh are wild goats, wild sheep, yak and special kinds of dogs. The animals are reared to
provide for the milk, meat and hides. Yak’s milk is used to make cheese and butter. The hair of
the sheep and goat is used to make woollens.
 The people here are either Muslims or Buddhists. In fact several Buddhists monasteries dot
the Ladakhi landscape with their traditional ‘gompas’. Some famous monasteries are Hemis,
Thiksey, Shey and Lamayuru.
 In the summer season the people are busy cultivating barley, potatoes, peas, beans and
turnip. The climate in winter months is so harsh that people keeping themselves engaged in
festivities and ceremonies. The women are very hard working. They work not only in the
house and fields, but also manage small business and shops. Leh, the capital of Ladakh is well
connected both by road and air. The National Highway 1A connects Leh to Kashmir Valley
through the Zoji la Pass.