A question may come in your Geography exam asking you to identify the layer of the earth that is in a semi-molten state.
First of all, it is important to understand the structure of the earth. The earth’s structure consists of the following layers:
- Crust: Continental Crust, Oceanic Crust
- Mantle: Upper Mantle, Lower Mantle
- Core: Outer Core, Inner Core
The layer of the earth that is in a semi-molten state is called asthenosphere found in the upper mantle. The upper mantle extends from the crust to a depth of about 410 kilometers. The asthenosphere is the denser, weaker layer beneath the lithospheric mantle. It lies between about 100 kilometers (62 miles) and 410 kilometers (255 miles) beneath Earth’s surface. The temperature and pressure of the asthenosphere are so high that rocks soften and partly melt, becoming semi-molten.