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Theory of Plate Tectonics Video Lecture | Social Studies (SST) Class 9

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FAQs on Theory of Plate Tectonics Video Lecture - Social Studies (SST) Class 9

1. What is the theory of plate tectonics?
Ans. The theory of plate tectonics is a scientific theory that explains the movement and interaction of the Earth's lithosphere, which is divided into several large plates. These plates float on the semi-fluid asthenosphere and are constantly moving, causing various geological phenomena such as earthquakes, volcanic activity, and the formation of mountains.
2. How are tectonic plates formed?
Ans. Tectonic plates are formed through a process called plate tectonics. The Earth's lithosphere is broken into several large and small plates, which are constantly moving due to convection currents in the underlying asthenosphere. These plates can be created through seafloor spreading, where new crust is formed at mid-ocean ridges, or through subduction, where one plate is forced under another at convergent boundaries.
3. What evidence supports the theory of plate tectonics?
Ans. Several lines of evidence support the theory of plate tectonics. Firstly, the fit of the continents, particularly between South America and Africa, is evidence that they were once connected. Secondly, matching rock formations and fossils on opposite sides of the ocean indicate that the continents were once joined. Additionally, the distribution of earthquakes and volcanic activity along plate boundaries provides further evidence for the movement of tectonic plates.
4. How do tectonic plates cause earthquakes?
Ans. Tectonic plates can cause earthquakes when they move past each other along faults. As the plates slowly grind against each other, stress builds up along the fault line. When the stress exceeds the strength of the rocks, it causes them to break and release energy in the form of seismic waves, resulting in an earthquake. The majority of earthquakes occur along plate boundaries, where the movement of plates is the most significant.
5. How does the theory of plate tectonics explain the formation of mountains?
Ans. The theory of plate tectonics explains the formation of mountains through the process of plate convergence. When two continental plates collide, neither can be subducted due to their low density. Instead, they crumple and fold, creating large mountain ranges. For example, the Himalayas were formed as the Indian Plate collided with the Eurasian Plate. The compression and uplift of crustal rocks during this collision led to the formation of the tallest mountain range in the world.
52 videos|413 docs|87 tests
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