GEOLOGY

Detailed explanation-1: -The mantle is heated from below (the core), and in areas that are hotter it rises upwards (it is buoyant), whereas in areas that are cooler it sink down. This results in convection cells in the mantle, and produces horizontal motion of mantle material close to the Earth surface.

Detailed explanation-2: -Mantle convection occurs because relatively hot rocks are less dense and rise in a gravitational field while relatively cold rocks are more dense and sink. The rise of hot rocks advects heat upward while the fall of cold rocks advects cold downward; this counterflow is equivalent to an upward heat flux.

Detailed explanation-3: -Convection currents drive the movement of Earth’s rigid tectonic plates in the planet’s fluid molten mantle. In places where convection currents rise up towards the crust’s surface, tectonic plates move away from each other in a process known as seafloor spreading (Fig. 7.21).

Detailed explanation-4: -Convection Currents The core’s heat energy is transferred to the mantle, causing it to rise towards the Earth’s surface, which is cooler. As the heated mantle transfers its heat energy to the lithosphere, it becomes more dense than the surrounding magma and sinks back down towards the core.

Detailed explanation-5: -Convection occurs because the density of a fluid is related to its temperature. Hot rocks lower in the mantle are less dense than their cooler counterparts above. The hot rock rises and the cooler rock sinks due to gravity.