Final answer:
The earth's crust and upper layer of the mantle are collectively called the lithosphere, which is divided into tectonic plates that are in constant motion due to plate tectonics.
Step-by-step explanation:
The earth's crust and upper layer of the mantle are collectively called the lithosphere. The lithosphere is divided into several tectonic plates that cover the Earth's surface. These plates float on the underlying semi-fluid asthenosphere and are constantly moving due to the process of plate tectonics.
Learn more about Plate Tectonics