The core difference is that continental drift describes the movement of continents across the Earth's surface, while plate tectonics explains that it's the tectonic plates (composed of both continental and oceanic crust), not just the continents, that are moving.
Here's a more detailed breakdown:
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Continental Drift: Proposed by Alfred Wegener, this theory suggests that continents were once joined together in a supercontinent called Pangaea and have since drifted apart. While Wegener provided evidence like matching coastlines, fossil distribution, and similar rock formations, he couldn't explain how the continents moved.
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Plate Tectonics: This is the modern, comprehensive theory that explains the "how." It posits that the Earth's lithosphere (crust and upper mantle) is broken into large and small plates that move and interact with each other. These plates "float" on the semi-molten asthenosphere. The movement of these plates is driven by convection currents in the mantle.
Key Differences Summarized:
| Feature | Continental Drift | Plate Tectonics |
|---|---|---|
| What moves? | Continents | Tectonic plates (lithosphere) |
| Mechanism? | Unexplained | Mantle convection, ridge push, slab pull |
| Scope? | Limited to continental movement | Explains a wide range of geological phenomena (earthquakes, volcanoes, mountain building) |
| Crust Type? | Primarily focused on continental crust | Includes both continental and oceanic crust |
In essence, the Theory of Plate Tectonics builds upon and replaces the Theory of Continental Drift by providing a mechanism and a broader understanding of Earth's dynamic processes. Plate Tectonics highlights that continents are just part of the larger moving plates.
