Transcript 4 - Theory of Plate Tectonics

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
Late 1900’s
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.
Crustal Plates
Earth’ Layers
Lithosphere
Asthenosphere
Earth Layers
Convection Currents of Magma
Plate Boundary Motion
CONVERGE - Moving toward one another.
connecting
DIVERGE – Moving apart.
dividing
TRANSFORM – Sliding past one another.
Plate Tectonics II Plates, Plate Boundaries, and Driving Forces
http://www.visionlearning.com/library/module_viewer2.php?mid=66&l=&let1=Ear
http://www.wwnorton.com/college/geo/egeo/flash/2_6.swf
Plate Boundaries
Convergent Boundary
Oceanic Crust – Continental Crust
Features
Tectonic plates connecting •Subduction Zone
Narrative and animation by:
Monte Hieb and Nancy Hieb
[email protected]
•Trench
•Volcanic Mountain Arc
Converging Oceanic Continental
Plates
Mt. St. Helens,
Washington
Convergent Boundary
Continental Crust – Continental Crust
Tectonic plates connecting
Features
http://www.pbs.org/wgbh/aso/tryit/tectonics/
convergent.html
•Folded Mountains
Converging Continental Pates
Himalayas
Convergent Boundary
Oceanic Crust – Oceanic Crust
Features
Tectonic plates connecting •Subduction Zone
•Trench
http://www.pbs.org/wgbh/aso/tryit/tectonics/
convergent.html
•Island Arc
Converging Oceanic Plates
Subduction
Zone
Japan – island arc
Divergent Boundary
Tectonic plate dividing
Narrative and animation by:
Monte Hieb and Nancy Hieb
[email protected]
http://www.pbs.org/wgbh/aso/tryit/tectonics/
divergent.html
Features
•Mid-Ocean Ridge
•Rift Zone
Diverging
Boundary
Transform Boundary
http://www.pbs.org/wgbh/aso/tryit/tectonics/transform.html
http://www.wwnorton.com/college/geo/animations/transform_faulting.htm
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
Magma has broken
through crust as the
plate moves over a
spot
Hot Spots
http://www.wwnorton.com/college/geo/animations/hot_spot_volcanoes.htm
http://www.classzone.com/books/earth_science/terc/content/inves
tigations/es0810/es0810page03.cfm?chapter_no=investigation
Additional Animations
•
http://www.seed.slb.com/flash/science/features/earth/livingplanet/plate_
boundaries/en/index.html?width=570&height=475&popup=true