- 2075 Chaitra · 2 marks
Short note: Mantle
Short answer
The mantle is Earth's thickest layer (to 2900 km, 84% volume), made of solid peridotite (Mg-Fe silicates) that flows slowly. It includes the plastic asthenosphere; P and S waves pass through it. Convection currents in the mantle drive plate tectonics.
Write a short note on the mantle of the earth.
The mantle is the thick layer of the Earth between the crust and the core. It lies below the Mohorovicic discontinuity (about 5-70 km) and extends to 2900 km, where the Gutenberg discontinuity separates it from the core. It forms about 84% of Earth's volume.
- Composition: dense ultramafic silicate rock, mainly peridotite, rich in magnesium and iron (olivine, pyroxene).
- Density: about 3.3 g/cm³ at the top to 5.5 g/cm³ at the base.
- Temperature: about 1000 °C at the top to over 3000 °C at the base.
- Divisions: upper mantle (to about 700 km, including the plastic asthenosphere) and lower mantle (700-2900 km).
- Slow convection currents in the mantle are believed to move the lithospheric plates.
- Both P and S waves pass through it, so it is solid, though it flows very slowly.
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