Evolution of Earth:
Our Earth is still evolving from 4.6 billion years to the present. Initially, the earth was a barren, rocky, and hot object with a thin atmosphere of hydrogen and helium, now we have a green environment which is favoring the existence of life.Our earth has four major components, the evolution of earth can be understood by understanding the evolution of these four components.
- Lithosphere Evolution
- Evolution of Atmosphere
- Evolution of Hydrosphere
- Evolution of Biosphere
Development of lithosphere
The lithosphere is a solid part of the earth. The present lithosphere evolved due to the process of differentiation. The separation of lighter materials and denser materials is called the process of differentiation. In Earth's layer formation and the process of differentiation happened in two stages:
- In the first stage, a gradual increase in the density inside the earth leads to a rise in temperature. As a result, materials inside the earth started getting separated based on density; heavy materials such as Iron sink towards the core, and lighter materials such as Silicon and Aluminium move towards the surface. This led to the development of the outer surface is called the crust.
- In the second stage, during the formation of the moon and due to a giant impact, the earth was further heated up and the process of differentiation happened again which led to the creation of three that is crust, mantle, and core.
Evolution of atmosphere and hydrosphere
The present atmosphere is made by three stages:First stages:
Loss of primordial atmospheres such as helium and hydrogen, Due to solar winds and the smaller size of the earth( lower gravitational force), the earth can not hold these gases and it blew off.
The hot interior of the earth contributed to the evolution of the atmosphere. During the cooling, gases, and water vapor from the interior of the earth came out into the atmosphere. At this stage, the atmosphere is largely comprised of water vapor, nitrogen, carbon dioxide, methane, ammonia, and very little free oxygen. This process is called degassing.
Third stage:
The composition of the atmosphere was modified by living organisms through photosynthesis and oxygen began to flood the atmosphere.
Carbon dioxide in the atmosphere gets dissolved in rainwater and further decreases causing more condensation and more rain.
Evolution of Biosphere or origin of life:
The origin of life is a type of chemical reaction. First, complex organic molecules are generated from inorganic things and they can duplicate themselves. Around 3000 million years ago, life began from blue algae.
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