Question

explain in details about four realms of earth?

Answer 1

The realm of land is called lithosphere, the realm of water is called hydrosphereand the realm of air is called atmosphere.The narrow zone where land, water and air meet is called biosphere. It is the fourth realm of the earth and it supports life.One of the reasons for supporting life is that the earth has plenty of water on its surface. The first life on the earth is originated in water.The outer solid layer of the earth is called crust or lithosphere. The word lithosphere comes from a Greek word Lithos which means rock. So, the crust or lithosphere is made up of rocks.About one-third of the earth’s surface is occupied by land and the rest is covered with waterVast land masses rising above the sea level are called continents.There are seven continents in the world. They are Asia, Europe, Africa, North America, South America, Australia andAntarctica.The continents are separated from one another by huge bodies of water called oceans.The level of the oceans is all the same and this level of water is called the sea level.About 250 million years ago, all the continents were joined to form one huge landmass called Pangea.Asia is the largest continent in the world.Europe and Asia continents form a single landmass. They are separated by the Ural Mountains and the Black Sea. These two continents are collectively known as Eurasia.Africa is the second largest continent next to Asia. The equator passes through the middle of this continent. But the portion lying in the northern hemisphere is bigger than the part lying in the southern hemisphere.North America and South America are connected by a narrow strip of land called the Isthmus of Panama. North America lies in the northern hemisphere while the South America lies in the southern hemisphere.Australia is the smallest continent. It lies in the southern hemisphere. Since it is small and surrounded by oceans on all sides it is called Island Continent.Antarctica is situated in the southernmost part of the earth. The South Pole lies in the centre of this continent. This continent is covered by thick ice all the year round and seen as snow-white. Therefore, it is also known as the White continent.The Climate of Antarctica is not suitable for human habitation.There are three Major Landforms of the earth. Highland region having pointed peaks are called mountains. Highland regions having flat summits are known as plateaus. Lowland regions of flat and level surface are called plains.Mountains rise several thousand metres above the sea level. When such highlands form a long chain, they are known as mountain range. At some places, they may occur in a series of parallel ranges. The Himalayas in the north of India have three parallel ranges.Young mountains are very high but old mountains are low and rounded. Old mountains become low and rounded because they have been eroded over the years.The Himalayas and the Rockies are young mountains while the Aravallis and the Urals are old mountains.Mountains are not suitable for human settlement because it is difficult to construct roads and railways in such highlands.The highest point on the earth’s surface is Mount Everest (8,848 m) in the Himalayas (Asia).Elbrus (5,633 m) is the highest peak in Europe.Kilimanjaro (5,895 m) is the highest peak in Africa.McKinley (6,194 m) is the highest peak in North America.Aconcagua (7,022 m) is the highest peak in South America.Kosciusko (2,230 m) is the highest peak in Australia.Vinson Massif (4,897 m) is the highest point in Antarctica.Plateaus look like a table and hence it is known as tableland.The highest plateau in the world is the plateau of Tibet. It is often called theroof of the world.Plateaus are moderately populated.Plains are found along the sea coasts or in the river valley.Rivers originating from mountains carry large amount of silt. They deposit the materials either in the sea or along their banks. These deposits are responsible for the formation of plains.Silt deposits made by rivers are known as alluvium. Alluvial deposits form the most fertile lands. Thus, plains are suitable for agricultural activities. And plains are thickly populated.The island of Mauna Kea in Hawaii is a submarine mountain. I