Evolution of Earth
Evolution of Earth is old phenomena but some believes that evolution of earth is a continuous phenomena. Typically, when the word “evolution” is used, it refers to the biological evolution of living organisms. Other types of “evolution” exist, such as the processes by which the universe, stars, galaxies, and planets form and change over time. Despite the wide variety of procedures involved, each of these circumstances changes with time.
Evolution of Earth & Earlier Theories
Nebular Theory or Nebular Hypothesis
In the previous theories, scientists and philosophers put out their interpretations and theories regarding how the world evolved. Immanuel Kant, a German philosopher, proposed one such theory, which the mathematician Laplace later improvised.
This hypothesis focused on how the planets—including the earth—formed from a cloud known as a nebula and later changed in response to their environment. In 1900, Chamberlain and Moulton proposed the idea that planets formed from the smoke produced by the movement of a rapidly approaching star towards the sun (essentially, a fusion-type event).
These balls of smoke gradually condensed as the solar system moved, which culminated in the formation of planets. Sir James Jeans and Sir Harold Jeffrey provided strong support for this idea.
The Binary theories, which were developed in the 1950s, postulated that the sun had a kind of companion for itself that was composed of components like hydrogen and helium. The particles that they back then referred to as “dust” helped these elements assist the development of the planets. Otto Schmidt and Karl Weizascar, both from Germany and Russia, respectively, presented this notion.
Evolution of Earth & Modern Theories
The Big Bang Theory
The “Expanding Universe Hypothesis” proposed by Edwin Hubble provided conclusive evidence that the universe is expanding and will continue to do so. The “Big Bang Theory” served as the foundation for this. This hypothesis operates similarly to how adjacent balloons expand, with greater distances between the next balloons.
The different elements that make up the cosmos are similar. According to the hypothesis, the earth was originally shaped like a ball of stuff that exploded to create the cosmos as we know it today. This procedure took around 13.7 billion years to complete. After approximately 300,000 years of this evolution process, the matter condensed to obtain the current shape of the universe. In contrast, Hoyle’s theory indicated that the earth was constantly in a stable state, which ran counter to this.
In different portions of the universe, there were distinct types of gravitational forces. As a result, various kinds of matter were attracted together to form the galaxy. There are many stars in a galaxy, and the distance between them is measured in light-years.
There were several stages in the formation of the planets:
- Gases make up the majority of stars.
- A gas cloud results from their assemblage.
- Around the gas core, dust forms.
- Smaller round objects known as planetesimals are created by the condensing of this matter, and after these objects collide and eventually cling together, planets, which are larger than planets, are created.
Evolution of Earth in Various Forms
Evolution of Lithosphere
The crust, mantle, outer core, and inner core are the various layers of the Earth as seen from the surface. The density of the Earth increases as it moves towards its centre. The temperature of the interior of the Earth rises along with the density as the particles are separated from one another according to densities.
Lighter elements migrate to the top, while iron and other dense materials migrate to the middle. When material cools, freezes, and condenses over time into a compact size, the Earth’s crust is created.
Evolution of Atmosphere
Nitrogen, carbon dioxide, free oxygen, water vapour, methane, and ammonia made up the atmosphere’s initial composition. One technique that resulted in the release of gas from the Earth’s interior was degassing. This plays a significant role in the Earth’s genesis and evolution. Since the solar breeze was powerful so close to the Sun, a lot of dust and gases from terrestrial planets were also blown by it. The evolution of the current atmosphere was facilitated by the escape of gases and water vapour from the interior surface of Earth during its cooling process.
Evolution of Hydrosphere
Because of photosynthesis, which later reached the atmosphere some 2,000 million years ago, the oceans were saturated with oxygen. Numerous oceans were created as a result of the enormous amounts of precipitation that filled the depressions with rainfall. Rainfall increased as a result of atmospheric carbon dioxide dissolving in rainwater, which resulted in a drop in temperature and the formation of condensation. There are vast quantities of gases and water vapour in the atmosphere as a result of frequent volcanic eruptions. These water vapours turned into water droplets when the Earth cooled, causing rainfall.
Evolution of Earth & Geological Time Scale
Below given is the representation of evolution of earth and geological time scale. Students can go through the table below:
Evolution of Earth UPSC
The Earth’s evolution is a crucial subject for the Civil Services exam. Aspirants can glance at the significant details that will cover the complete Geography curriculum by looking at the Geography Notes for UPSC. Students can read all the details related to UPSC by visiting the official website of StudyIQ UPSC Online Coaching.