The highly viscous, mechanically-weak and ductile region of Earth's upper mantle is called:

Question

Question

This question was previously asked in

SSC Selection Post 2024 (Higher Secondary Level) Official Paper (Held On: 25 Jun, 2024 Shift 2)

Answer 1

The correct answer is asthenosphere.

Key Points

Asthenosphere:
- 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.
- The asthenosphere is generally more viscous than the lithosphere, and the lithosphere-asthenosphere boundary (LAB) is the point where geologists and rheologists, scientists who study the flow of matter mark the difference in ductility between the two layers of the upper mantle.

F1 Lalita V Anil 28.04.21 D10

Additional Information

The crust and the uppermost part of the mantle are called the lithosphere.
- Its thickness ranges from 10-200 km.
- The lithosphere is the solid, outer part of the Earth.
- The lithosphere includes the brittle upper portion of the mantle and the crust, the outermost layers of Earth’s structure.
- It is bounded by the atmosphere above and the asthenosphere (another part of the upper mantle) below.
exosphere:
- The uppermost layer of the atmosphere above the thermosphere is known as the exosphere.
- This is the highest layer but very little is known about it.
- Whatever contents are there, these are extremely rarefied in this layer, and it gradually merges with the outer space.

Mesosphere:
- The mesosphere is a layer of Earth's atmosphere.
- The mesosphere is directly above the stratosphere and below the thermosphere.
- It extends from about 50 to 85 km (31 to 53 miles) above our planet.
- Temperature decreases with height throughout the mesosphere.