A model of convection
When a solid, liquid, or gas is heated, it expands, becomes less dense, and rises. When it cools, it contracts, becomes more dense, and sinks. The circulation that results from hot, rising material and cool, sinking material is known as convection. The model in front of you demonstrates this fundamental process, which operates in the atmosphere, the ocean, and the solid Earth. Convection makes the Earth dynamic.
Exploring the interior
Shock, or seismic waves from earthquakes and explosions reveal the earth’s internal structure. Sharp differences in rock density change the speed at which the waves travel through the Earth. Seismic waves indicate that the Earth has a layered structure.
Topic: Earth Science
Subtopic: Earth Structure
Keywords: density, Earth (Planet)--Mantle, Geology, Stratigraphic, Geology, Structural, Heat--Convection, Seismic waves, Seismology