Chapter Notes and Summary
• There are three main components of environment – Lithosphere, Atmosphere and Hydrosphere.
• solid portion of Earth on which we live is called Lithosphere.
• gaseous layer that surrounds Earth is Atmosphere.
• area covered by water is called Hydrosphere.
• zone which contains all forms of life is called Biosphere.
• It comprises rocks of earth’s crust and thin layers of soil.
• There are two main divisions of earth’s surface.
• large landmasses are known as continents.
• huge water bodies are called ocean basins.
• Elevation of land is measured from level of sea, which is taken as zero.
• highest mountain peak Mt. Everest is 8,848 metres above sea level.
• greatest depth of 11,022 metres has been recorded at Mariana Trench in Pacific Ocean.
• There are seven major continents.
• greater part of land mass lies in Northern Hemisphere.
• Asia is largest continent.
• combined landmass of Europe and Asia is called Eurasia.
• Europe is much smaller than Asia.
• Africa is second largest continent. It is only continent through which Tropic of Cancer, Equator and Tropic of Capricorn pass.
• world’s largest hot desert is Sahara Desert.
• world’s longest river is Nile.
• North America is third largest continent of world.
• South America and North America are linked by a very narrow strip of land called Isthmus of Panama.
• world’s longest mountain range is Andes.
• Amazon is world’s largest river.
• Australia is smallest continent. It is also called an island continent.
• Antarctica is permanently covered with thick ice sheets.
• India has research station named as Maitri and Dakshin Gangotri at Antarctica.
• More than 71 % percent of Earth is covered with water therefore Earth is called blue planet.
• More than 97% of Earth’s water is found in oceans.
• four major oceans are Pacific Ocean, Atlantic Ocean, Indian Ocean and Arctic Ocean.
• Pacific Ocean is largest ocean.
• Atlantic Ocean is second largest ocean.
• Indian Ocean is only ocean named after a country, that is India.
• Arctic Ocean is located within Arctic Circle.
• Atmosphere protects us from harmful effects of sun’s rays.
• atmosphere extends up to a height of about 1,600 kilometres.
• atmosphere is divided into five layers—the troposphere, stratosphere, mesosphere, thermosphere and exosphere.
• atmosphere is composed mainly of nitrogen and oxygen.
• Air moves from high pressure to low pressure. Moving air is known as wind.
Biosphere – Domain of Life
• biosphere is narrow zone of contact between land, water and air.
• All living organisms including humans are linked to each other and to biosphere for survival.
• organisms in biosphere may broadly be divided into plant kingdom and animal kingdom.
• Increase in amount of CO2 leads to increase in global temperature. This is termed as global warming.
Chapter Notes and Summary