The churning Earth
The mantle is mostly solid rock, but because it is hot, it flows in slow, circulating patterns. Hotter, less dense rock rises and cooler, more dense rock sinks. This process, known as convection, is the force that powers plate tectonics-the movement of plates over the Earth’s surface. This image is a vertical cross section through the mantle showing hotter (reds) and cooler (blues) regions. These variations in temperature are modeled from changes in the velocity of earthquake-generated seismic waves passing through the mantle.
Topic: Earth Science
Subtopic: Earth Structure
Keywords: Earth (Planet)--Mantle, Geology, Stratigraphic, Heat--Convection, Plate tectonics
When a solid, liquid, or gas is heated, it expands, becomes less dense, and rises.
We know the composition of the uppermost mantle because we have samples of it.
At the center of the Earth is the dense, hot core.
In the first century A.D., in China, it was recognized that the Earth is surrounded by a magnetic field.