Plate Movement and Plate

BoundariesChapter 4, Section 3

Plate Tectonics TheoryLithosphere is divided into plates

Plates move around on the asthenosphere

3 Causes of plate motion

Slab PullOceanic plate sinks (more dense)

Pulls rest of tectonic plate with it

Ridge PushOceanic crust is higher at ridge

Pushes plate underneath continent

ConvectionHappens in asthenosphere

Hot magma rises, cool magma sinks

Drags plates sideways

3 Types of Plate Boundaries

ConvergentDivergentTransform Fault

Convergent Boundaries

Continent / Continent

Plates thicken and buckle

Push upwardsMountain formation

Continent / OceanicOceanic plate sinks (more dense)

Subduction zoneTrenches formVolcanic mtns on coast

Oceanic / OceanicOne slides under the other

Subduction zonesVolcanic Islands

Divergent BoundaryPlates spread apartMagma risesNew lithosphere formed

Mid – Atlantic Ridge

Transform Boundary

Plates slide past each other

Produce earthquakes

Types of Plate Boundaries:Types of Plate Boundaries:

DivergentDivergent

ConvergentConvergent

TransformTransform

Continent / Continent Examples

•Appalachian Mtns.

•Atlas Mtns.

Continent / Oceanic Examples

•Andes•Cascades

•Mt. St. Helens

Oceanic / Oceanic Examples

•Aleutians•Japan

•Philippines

Plate MovementPlate Movement

•Approx. 3-6 cm per year

•Rate a fingernail grows!

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