Page 97 - SST Class 07
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graphy                               Environment                  13

                                 Geo









             q   Components of environment                          q   Natural environment
             q   Human environment

            Introduction                                            elements    of   natural   environment.     Natural
                                                                    environment provides us the base for our
            The word environment      means surroundings or
                                                                    existence, like land to live on, air to breathe,
            conditions in which a person, animal or plant lives
                                                                    water to drink and food to eat. It consists of four
            or operates. It includes everything on, in and          realms—lithosphere  ,   atmosphere  ,  hydrosphere
            around the earth and how each of these elements
                                                                    and biosphere  .
            affect the others. The existence, survival and
            growth of a living being depend on the things or        Activity
            conditions that surround it. If these conditions or      Visit a garden and zoo. Take photographs of five
            things are removed, the existence, survival and          animals and five plants living there. These are
            growth of that living being will become impossible.      biotic elements. Try to find out how plants and
                                                                     animals are interdependent. Also find out how
                      COMPONENTS OF ENVIRONMENT                      biotic and abiotic elements are related.

            The environment is a whole unit, but it can be           Lithosphere
            divided into two parts—natural environment and          The thin and solid upper covering of the earth is
            human environment.
                                                                    known as lithosphere  . It is made up of rocks and
            The natural environment   includes all things, both     minerals and covered with a thin layer of soil. The
            living and non-living or biotic and abiotic. Biotic     average thickness of lithosphere is about 100 km.
            components include all biological or living beings      The lithosphere comprises both continents (29%)
            such as plants, animals, insects etc. Abiotic           and ocean beds (71%). Lithosphere has two
            components include all physical or non-living           layers—the sial  and the sima . Sial are rocks of the
            things such as land, minerals, soil, water and          continents rich in silica and aluminium. So it is
            climate.                                                called sial, taking si from silica and al from
                                                                    aluminium. Sima rocks form the ocean basin.
            The human environment        includes constructed
                                                                    These rocks have materials rich in silica and
            surroundings or built up areas like buildings,
            roads, machines and social and cultural factors,        magnesium. So it is called sima, taking si from
            like family and school.                                 silica and ma from magnesium.
                  F ind Outind Out                                  Lithosphere is very important for all sorts of life
                                                                    form. It provides us forests, grasslands, agricultural
            Which day is celebrated as the World Environment        land and land for human settlement. It is a source
            Day?                                                    of minerals wealth because all kinds of minerals
                                                                    and metals are embedded in the rock strata.
                          NATURAL ENVIRONMENT
                                                                     Hydrosphere
            Land, water, air, plants and animals are the
                                                                    The water which forms about three-fourths of our
                                                                                                    Environment
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