What is the lithosphere?

• A. The rigid outer layer of the Earth, consisting of the crust and the uppermost part of the mantle
• B. The liquid layer beneath the crust
• C. The inner core
• D. The atmosphere

Answer: (A)

Think of the lithosphere as Earth’s rigid outer shell. It includes the crust plus the uppermost portion of the mantle, forming solid plates that move on the softer layer beneath. The plates’ rigidity lets them crack and interact at boundaries, driving earthquakes and volcanoes. The layer below that is the asthenosphere, which is weaker and can flow slowly, allowing the plates to move. The atmosphere is outside Earth, and the inner core is far deeper at the center, not the outer shell. So the best description is the rigid outer layer made up of the crust and the upper mantle.