Which one of the following is found in the innermost part of the Earth?
Lehmann discontinuity
Understanding Earth's Interior: Layers and Discontinuities
The Earth's interior is made up of several distinct layers: the crust, the mantle, and the core. These layers are separated by transition zones where the physical properties, such as seismic wave velocity, change significantly. These transition zones are known as discontinuities.
Let's look at some important discontinuities within the Earth:
- Conrad discontinuity: This discontinuity is found within the Earth's crust, separating the upper continental crust (sial) from the lower continental crust (sima). It is not globally present and is more prominent under continents.
- Moho discontinuity (Mohorovičić discontinuity): This marks the boundary between the Earth's crust and the underlying mantle. It is a major discontinuity where seismic wave velocities increase sharply.
- Gutenberg discontinuity (Core-Mantle Boundary): Also known as the Wiechert-Gutenberg discontinuity, this is located at the boundary between the mantle and the outer core. Seismic waves (specifically S-waves) cannot pass through the outer core, which is believed to be liquid, and P-wave velocity decreases significantly here.
- Lehmann discontinuity: This discontinuity is found within the Earth's core. It separates the liquid outer core from the solid inner core. It is located at a depth of approximately 5150 km.
The question asks which discontinuity is found in the innermost part of the Earth. Considering the layers from the surface inward:
- Crust (includes Conrad, boundary is Moho)
- Mantle (boundary with core is Gutenberg)
- Core (Outer Core and Inner Core, boundary is Lehmann)
The innermost part of the Earth is the inner core. The discontinuity that marks the boundary within the core, separating the outer core from the inner core, is the Lehmann discontinuity. Therefore, the Lehmann discontinuity is found in the innermost part of the Earth.
Here is a summary of the discontinuities and their locations:
| Discontinuity | Location |
|---|---|
| Conrad discontinuity | Within the continental crust |
| Moho discontinuity | Between Crust and Mantle |
| Gutenberg discontinuity | Between Mantle and Outer Core |
| Lehmann discontinuity | Between Outer Core and Inner Core (within the Core) |
Based on the locations, the Lehmann discontinuity is found in the deepest and innermost part of the Earth among the options provided.
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Important Questions from Geomorphology
Sandstone is an example of:
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- Identify the third layer of soil from top.
The down fold in a rock is known as a/an:
