The Theory of Plate Tectonics and Related Concepts

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What does the theory of plate tectonics explain?

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The theory of plate tectonics explains how Earth’s outer shell, known as the lithosphere, is divided into several large and small plates that float on the semi-fluid asthenosphere beneath them.

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What is the lithosphere?

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The lithosphere is the rigid outer layer of the Earth, about 100 km thick, which includes the crust and the uppermost mantle.

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What is the asthenosphere?

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The asthenosphere is the layer of the Earth’s mantle located just below the lithosphere, allowing the plates to move.

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How do tectonic plates move?

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Tectonic plates move at varying rates, typically a few centimeters per year, causing most of Earth’s seismic and volcanic activity at plate boundaries.

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What are divergent boundaries?

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Divergent boundaries are where plates move apart, and new crust is formed from upwelling magma, as seen at mid-ocean ridges.

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What are convergent boundaries?

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Convergent boundaries are where plates move towards each other, and one plate is often forced beneath another in a process called subduction.

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What are transform boundaries?

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Transform boundaries are where plates slide past each other horizontally, leading to earthquakes along faults like the San Andreas Fault.

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Who proposed the idea of continental drift?

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Alfred Wegener proposed the idea of continental drift, which later contributed to the development of the theory of plate tectonics.

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What evidence supports the theory of plate tectonics?

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Evidence includes seafloor spreading, magnetic stripes, age of the ocean floor, ocean trenches, and the distribution of earthquakes and volcanoes.

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What is seafloor spreading?

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Seafloor spreading is the process where magma rises at mid-ocean ridges, creating new oceanic crust as it cools and solidifies.