Theory of Plate Theory Tectonics of Plate Tectonics

Theory of Plate Theory. Tectonics of Plate Tectonics: • Lithosphere is broken up into many plates that move • Interactions when the plates touch, explain most of the Earth’s land ocean features • Earthquakes can occur at all plate boundaries

Plate Boundaries Transform Divergent Convergent

What happens at a divergent boundary? • Motion: Plates moving apart • Features/Processes: o Sea floor spreading o Mid-ocean ridge o Volcanic activity Ex: Mid-Atlantic Ridge

Ex: The Great Rift Valley • Divergent boundary on a continent • New ocean forming

Diverg. Bound_PC

What happens at a transform boundary? • Motion: Plates slide past each other • Features/Processes: Many earthquakes

Ex: San Andreas Fault

What happens at a convergent boundary? • Motion: Plates are pushed together • Features depend on which types of plates are converging (details below)

Convergent (oceanic crust vs. continental crust) • Oceanic subducts under continental because… o The oceanic crust has a greater density • Trench is created off the coast • Volcanic Mountains created on land due to rising magma ma gm a

Ex: The Andes Mountains

Convergent (oceanic crust vs. oceanic crust) m ag m a • The OLDER oceanic plate will sink beneath the newer o The older plate is denser b/c it has more time to compact • Trench is created in between the plates • A volcanic island arc is created due to rising magma

Examples: Island Arcs of 1. Aleutian Islands, Alaska 2. Japan 3. The Philippines

Convergent (continental vs. continental) • Both plates collide and deform o neither subducts because both plates have similar, low densities • The crust thickens as mountains are pushed upward o metamorphism of rocks takes place from pressure

Ex: The Himalayas

Converg. Marg. V 2

Motion. At. Plate_PC

Explain this diagram: 1 2 3 4