The Composition of the Earth

  1.   Lithosphere . The lithosphere  is the rigid, outermost layer of the Earth. It is composed of the crust and the portion of the upper mantle that behaves elastically on time scales of thousands of years or greater. It is an average of 100km thick. The lithosphere is the outermost layer, meaning its outer boundary is the atmosphere, hydrosphere and biosphere. The inner boundary of the lithosphere is the  asthenosphere ,  which is a plastic-like layer of the mantle that the lithosphere "floats" on.  The outermost layer of a rocky planet, the crust, is defined on the basis of its chemistry and mineralogy. This includes the crust and the uppermost mantle, which constitute the hard and rigid outer layer of the Earth.  The uppermost part of the lithosphere that chemically reacts to the atmosphere, hydrosphere  and biosphere through the soil-forming process is called the   pedosphere. Continents and oceans are...

  2.  Atmosphere The atmosphere is the thin blanket of air around the earth that consists of various gases. The atmosphere is held by the earth due to its gravitational pull. The most important layer of the atmosphere is the area that extends up to 120km from the surface of the earth. 50% of the total air content of the atmosphere is present in the region that extends up to 5-6km from the earth’s surface. (David Waugh-2000)  The atmosphere is immensely important for the existence of living beings and plant life as it provides oxygen for respiration of living beings and the necessary carbon dioxide for the process of Photosynthesis. The atmosphere mainly consists of various gases, and it also contains water vapor, dust and salt particles. As a result of different human activities and natural phenomena (Exhaustion of gases during volcano eruptions, release of methane from marshes etc.) natural gases like  Carbon Dioxide, Methane, Carbon Monoxide and Sulphur Dioxid...

  3. Hydrosphere          The entire body of water on the surface of the earth in various forms is termed the hydrosphere.   The hydrosphere is the combined mass of water found on, under, and above the surface of the earth. It has been estimated that there are 1386 million cubic kilometers of water on earth (Environemtal Geography 1996). This includes water in liquid and frozen forms in groundwater, oceans, lakes and streams. Approximately 75% of Earth’s surface, an area of some 361 million square kilometers, is covered by ocean.     Distribution of water on the Earth. Water can be seen in different forms on earth as follows.  Ocean water (in oceans and seas) Surface water (on the surface of the land, rivers, streams, lakes and reservoirs) Ground water (water deposited underground.) Atmospheric water (Atmospheric humidity) Soil water (water in soil) Out of the total volume of global water only 1% or a very limited amount o...

    4. Biosphere The total ecological systems integrating plant and animal life which constantly interact with the Earth is turned the biosphere. The existence of the biosphere depends on the interaction of the atmosphere, lithosphere, and hydrosphere with each  other. The biosphere is a narrow zone on the surface of the earth where soil, water, and air combine to sustain life. Life can only occur in this zone. From fungi and bacteria to large animals, there are several different types of life. The biosphere is characterized as an area that contains all living organisms and the products of their activities. As a result, it plays a critical role in the maintenance of ecosystems, i.e., the existence of species and their reciprocal interactions. And the biosphere is critical for climate regulation. There are two factors that effects the processes in the biosphere. 1. Living components          - (plants, animals and biosphere) 2. Non-living...