Mass and Energy: Interactions of the Earth System

The Earth’s surface processes are predominantly controlled by the interaction between the Earth’s internal heat and solar radiation. Surface heat-flow measurements reflect the increase in temperature with depth, which results in flow of the Earth’s internal heat from the core, through the mantle, to the surface. Heat-flow is highest in volcanically active regions and is lowest near oceanic trenches. The source of the Earth’s internal heat comes from a combination of processes, which include the formation of the planet and its internal layers and the decay of its radioactive elements, which release heat as the unstable parent element is converted to a stable daughter element. Radioactive decay is the primary agent responsible for convection in the mantle that, in turn, results in plate tectonics.