The Geotectonics course is a discussion of the mechanics of the earth. We begin with a detailed review of Plate Tectonic Theory, including its supporting evidence and the history of its development and acceptance. From our investigation of Plate Tectonics we proceed to such topics as: mechanical and compositional layering of the Earth, plate kinematics and the driving forces behind plate tectonics. We then turn to the evolution of Earth's lithosphere, the nature of tectonic plate boundaries, and the process acting to shape regional-scale Earth structures, such as mid-ocean ridges, strike-slip fault zones, volcanic arcs and mountain belts. Precambrian and Phanerozoic tectonics will be discussed and contrasted.