Plate Tectonics Advanced

Convergent, divergent, and transform boundaries in 3D

Plate tectonics is the unifying theory of Earth science. Earth's lithosphere is broken into ~15 major plates floating on the asthenosphere. Three types of plate boundaries exist: (1) Divergent — plates move apart at mid-ocean ridges, where magma rises to create new oceanic crust. The Mid-Atlantic Ridge spreads ~2.5 cm/yr. (2) Convergent — plates collide. Ocean-continent convergence creates subduction zones (ocean plate dives under continent), forming volcanic arcs (Andes) and deep trenches (Mariana Trench, 11 km). Ocean-ocean convergence creates island arcs (Japan). Continent-continent collision builds fold mountains (Himalayas). (3) Transform — plates slide laterally past each other, causing earthquakes (San Andreas Fault). The driving forces are slab pull (gravity pulling cold, dense subducted lithosphere into the mantle) and ridge push (gravitational sliding off elevated ridges), both powered by mantle convection driven by Earth's internal heat.