Environmental Geography — Lesson 5
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. The Earth's lithosphere is divided into approximately 15 major tectonic plates and several smaller ones. These plates move at rates of 1–10 centimeters per year. Plate boundaries are classified into three types: divergent boundaries where plates move apart, convergent boundaries where plates collide, and transform boundaries where plates slide horizontally past each other.