1.4. Changing position of the continents and oceans

Key Concept:

Continents and oceans are not fixed but are continually changing positions due to tectonic processes, such as divergence, convergence, and subduction.

Short Notes:

Continental movement continues today. Tectonic plates float on the semi-fluid asthenosphere and move a few centimeters per year. These movements change the positions of continents and oceans gradually but continuously.

Divergent boundaries cause continents to split and oceans to form, as seen in the East African Rift Valley. Convergent boundaries push continents together and can form mountains, while transform boundaries result in earthquakes.

These changes have shaped global geography for millions of years and will continue to do so. Future continents may merge or split in new ways, forming future supercontinents over millions of years.

Key Terms:

• Tectonic Plates – Large pieces of Earth’s crust that move,
• Divergent Boundary – A plate boundary where plates move apart,
• Convergent Boundary – A boundary where plates collide,
• Transform Boundary – Plates slide past one another,
• Subduction – One plate moves under another at convergent boundaries,
• Asthenosphere – Semi-fluid layer beneath tectonic plates,
• Plate Boundary – Region where two tectonic plates meet.

Example:

The movement of the Arabian Plate away from the African Plate is widening the Red Sea, showing how oceans expand due to divergence.