Environmental Geography — Lesson 3
Plate tectonics is the unifying theory of Earth science that explains the distribution of geological features such as earthquakes, volcanoes, mountain ranges, and ocean basins. Earth's lithosphere is divided into approximately 15 major tectonic plates and several smaller ones that move at rates of 1–10 centimeters per year. These plates interact at three main types of boundaries: divergent boundaries where plates move apart, convergent boundaries where plates collide, and transform boundaries where plates slide horizontally past each other.