The mantle is special primarily due to the unique properties of its upper layer, which allows for the movement of Earth's tectonic plates.
The Asthenosphere: A Key to Plate Tectonics
A key feature of the upper mantle is the presence of the asthenosphere. This layer is not solid but rather a soft, weak zone that behaves like a very viscous fluid.
- Fluid-like Behavior: The asthenosphere's ability to flow is crucial. It allows the rigid lithospheric plates above to move slowly over the Earth's surface.
- Plate Movement: This movement is what causes earthquakes, volcanic eruptions, and the formation of mountain ranges. Without this flow, the Earth's surface would be static.
Why is this Fluid-like Behavior Important?
The fact that the asthenosphere flows is what makes the Earth dynamic. This single characteristic drives numerous geological processes, including:
- Plate Tectonics: The movement of lithospheric plates.
- Earthquakes: Result from the stresses built up as plates interact.
- Volcanism: Molten rock (magma) erupts at plate boundaries.
- Mountain Building: Occurs where plates collide and push against each other.
Summary
| Feature | Description | Importance |
|---|---|---|
| Asthenosphere | Soft, weak layer in the upper mantle, behaves like a very viscous fluid. | Allows movement of lithospheric plates, driving plate tectonics, earthquakes, volcanoes, and mountain building. |
The special nature of the mantle, and particularly the asthenosphere, is what enables the Earth's surface to be dynamic and constantly changing. Its fluid-like behavior is the driving force behind many geological processes, as stated in the provided reference, “the special about the upper mantle is its ability to flow like fluid. The upper mantle has soft weak layer called the asthenosphere, which capable of flowing. This property facilitates the movement of lithospheric plates.”
