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Plate Movement and Plate Boundaries. Chapter 4, Section 3. Plate Tectonics Theory. Lithosphere is divided into plates Plates move around on the asthenosphere. 3 Causes of plate motion. Slab Pull. Oceanic plate sinks (more dense) Pulls rest of tectonic plate with it. Ridge Push.
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Plate Movement and Plate Boundaries Chapter 4, Section 3
Plate Tectonics Theory • Lithosphere is divided into plates • Plates move around on the asthenosphere
Slab Pull • Oceanic plate sinks (more dense) • Pulls rest of tectonic plate with it
Ridge Push • Oceanic crust is higher at ridge • Pushes plate underneath continent
Convection • Happens in asthenosphere • Hot magma rises, cool magma sinks • Drags plates sideways
3 Types of Plate Boundaries • Convergent • Divergent • Transform Fault
Continent / Continent • Plates thicken and buckle • Push upwards • Mountain formation
Continent / Oceanic • Oceanic plate sinks (more dense) • Subduction zone • Trenches form • Volcanic mtns on coast
Oceanic / Oceanic • One slides under the other • Subduction zones • Volcanic Islands
Divergent Boundary • Plates spread apart • Magma rises • New lithosphere formed • Mid – Atlantic Ridge
Transform Boundary • Plates slide past each other • Produce earthquakes
Types of Plate Boundaries: Divergent Convergent Transform
Continent / Continent Examples • Appalachian Mtns. • Atlas Mtns.
Continent / Oceanic Examples • Andes • Cascades • Mt. St. Helens
Oceanic / Oceanic Examples • Aleutians • Japan • Philippines
Plate Movement • Approx. 3-6 cm per year • Rate a fingernail grows!