Chapter 27, Problem 11RQ

To determine

The cause of the convection currents

Answer to Problem 11RQ

The difference between the gravity and temperature sets up convection currents in mantle.

Explanation of Solution

The lithosphere is drifted due to the convection currents. These currents are produced in the mantle. The core temperature of the mantle is very high and as per the heat transfer. Heat always transfers from the higher temperature to the lower temperature. Thus heat flows from the core to the mantle.

Due to this process, the temperature of the rocks present in the mantle heated up, and their density also reduced. Because of the lower density of the rocks present in the mantle than the upper rocks, these rocks rise upward and more dense rocks take their place due to the gravity, which sets up the convection currents in the mantle.

Conclusion:

Therefore, the difference between the gravity and temperature sets up convection currents in mantle.