Key Concept:
Earth’s continents and oceans were formed over billions of years through cosmic, geological, and internal processes including the Big Bang, formation of the solar system, and tectonic activity.
Short Notes:
The origin of the Earth is closely linked with the formation of the solar system, which scientists believe began around 4.5 billion years ago following the Big Bang — a massive cosmic explosion. From swirling dust and gas around the Sun, planets including Earth were formed. Over time, solid rock masses cooled and created Earth’s early crust.
The first supercontinent believed to form was Rodinia, followed by Gondwana, and later the most famous, Pangaea. These supercontinents broke apart due to internal forces such as convection currents in the mantle. The break-up of Pangaea began around 255 to 210 million years ago, dividing into two large landmasses: Laurasia in the north and Gondwanaland in the south.
As these landmasses continued to move apart through processes like sea-floor spreading, modern continents and ocean basins took shape. The Atlantic Ocean, for example, was formed between separating continents. This process continues today through the movement of tectonic plates.
Key Terms:
- Big Bang – Origin of the universe through a massive explosion,
- Solar System – Sun and planets formed from cosmic dust,
- Rodinia – First known supercontinent,
- Pangaea – A supercontinent formed about 255–210 million years ago,
- Laurasia – Northern portion of Pangaea,
- Gondwanaland – Southern portion of Pangaea,
- Continental Drift – Slow movement of continents over Earth’s surface,
- Sea-floor Spreading – Creation of new ocean crust at mid-ocean ridges.
Example:
The formation of the Red Sea is a result of tectonic divergence between the African and Arabian plates, showing how continental drift leads to ocean creation.
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