Theory of Plate Tectonics

• Theory• Plate Boundaries

– Convergent– Divergent– Transform

• Hot Spots

What is a SCIENTIFIC THEORY?

A well tested concept that explains a wide range of observations

• In 1965, J. Tuzo Wilson, a Canadian scientist proposed the theory of Plate Tectonics– Combined knowledge of sea-floor spreading

with continental drift

Theory of Plate Tectonics

Earth’s lithosphere is broken into sections called plates.

Plates are always shifting and moving.

Movement is driven by convection currents in the mantle.

Evidence: All the evidence collected over the 1900’s was used in this theory.

Late 1900’s

Crustal Plates

Lithosphere

Asthenosphere

Earth LayersEar

th’ L

ayer

s

Convection Currents of Magma

Plate Boundary MotionCONVERGE - Moving toward one another.

connecting

DIVERGE – Moving apart.

dividing

TRANSFORM – Sliding past one another.

Plate Tectonics II Plates, Plate Boundaries, and Driving Forceshttp://www.visionlearning.com/library/module_viewer2.php?mid=66&l=&let1=Ear

Plate Boundarieshttp://www.wwnorton.com/college/geo/egeo/flash/2_6.swf

Narrative and animation by:Monte Hieb and Nancy Hieb

mhieb@geocraft.com

Convergent BoundaryOceanic Crust – Continental Crust

Features

•Subduction Zone

•Trench

•Volcanic Mountain Arc

Tectonic plates connecting

Converging Oceanic Continental Plates

Mt. St. Helens,Washington

http://www.pbs.org/wgbh/aso/tryit/tectonics/convergent.html

Convergent Boundary

Continental Crust – Continental Crust

Features

•Folded Mountains

Tectonic plates connecting

Converging Continental Pates

Himalayas

http://www.pbs.org/wgbh/aso/tryit/tectonics/convergent.html

Convergent Boundary

Oceanic Crust – Oceanic Crust

Tectonic plates connecting

Features

•Subduction Zone

•Trench

•Island Arc

Converging Oceanic Plates

Subduction

Zone

Japan – island arc

Narrative and animation by:Monte Hieb and Nancy Hieb

mhieb@geocraft.com

http://www.pbs.org/wgbh/aso/tryit/tectonics/divergent.html

Divergent Boundary

Features

•Mid-Ocean Ridge

•Rift Zone

Tectonic plate dividing

Diverging Boundary

http://www.pbs.org/wgbh/aso/tryit/tectonics/transform.htmlhttp://www.wwnorton.com/college/geo/animations/transform_faulting.htm

Transform Boundary

Plates move in opposite directions on either side of the transform boundary, causing earthquakes.

Plates move in similar directions on either side of the fracture zone (red dashed line), resulting in fewer earthquakes.

Transform Fault

San Andreas Fault

Hot Spots

http://www.classzone.com/books/earth_science/terc/content/investigations/es0810/es0810page03.cfm?chapter_no=investigation

Magma has broken through crust as the plate moves over a spot

http://www.wwnorton.com/college/geo/animations/hot_spot_volcanoes.htm

Additional Animations

• http://www.seed.slb.com/flash/science/features/earth/livingplanet/plate_boundaries/en/index.html?width=570&height=475&popup=true