What causes convection currents in the Earth's mantle?

Convection currents in the Earth's mantle are primarily driven by temperature and density variations. As the mantle material heats up near the core, it becomes less dense and begins to rise towards the Earth's crust. As this hot material rises, it cools, becomes denser, and eventually sinks back down. This cyclical process creates a flow of material within the mantle known as convection currents.

The relationship between temperature and density is crucial in understanding this mechanism. The material is constantly in motion due to the differences in thermal energy: hotter areas move upwards while cooler areas sink, establishing a continuous flow that drives plate tectonics on the Earth's surface.

While gravity and pressure play a role in the overall structure and behavior of the Earth's internal layers, it is the temperature differences that directly instigate the movement of mantle convection currents. Similarly, the rotation of the Earth affects patterns of movement and can influence surface phenomena but is not a direct cause of the convection process within the mantle. Magma movement is a result of these convection currents but does not directly explain the initial driving forces behind them.