AFOQT Practice Test

What is the lithosphere composed of?

1. Liquid iron at extreme temperatures

2. Tectonic plates and the upper mantle

3. A solid mixture primarily made of gases

4. Only sedimentary materials

The correct answer is: Tectonic plates and the upper mantle

The lithosphere is correctly identified as being composed of tectonic plates and the upper mantle. This outer layer of the Earth includes the crust, which is a solid layer of rock, and the uppermost part of the mantle, which is also solid but behaves as a viscous fluid over geological timescales. The lithosphere is rigid and relatively cool compared to the underlying asthenosphere, which is partially molten and allows the tectonic plates to move. Understanding the composition of the lithosphere is crucial, as it plays a key role in the dynamics of plate tectonics, which affects geological processes such as earthquakes, volcanic activity, and the formation of mountain ranges. The rigidity of the lithosphere contributes to the stability of continents and ocean basins, making its understanding vital for various fields including geology, seismology, and environmental science.