Answer:
The theory that the lithosphere is divided into tectonic plates that slowly move on top of the asthenosphere is called the theory of plate tectonics. The lithosphere is the outermost solid layer of the Earth, and it is divided into several large, irregularly-shaped plates that move relative to each other. The asthenosphere is the layer of the Earth's mantle that is directly below the lithosphere. It is made up of hot, plastic rock that can flow slowly over time.