The theory that states that the Earth's crust and rigid upper mantle move in different directions at various rates over the surface is called Plate Tectonics.

Here's a breakdown of the theory:

* The Earth's outer layer is made up of large, rigid plates. These plates are called tectonic plates, and they are constantly moving.

* The plates move over a hot, semi-fluid layer of the mantle called the asthenosphere. This movement is driven by convection currents within the mantle.

* The movement of these plates causes a variety of geological phenomena, including earthquakes, volcanic eruptions, mountain building, and the formation of new ocean floor.

Let me know if you would like more information about Plate Tectonics!