Plate Boundaries

Continental Drift Review

• Breakup of Pangaea

• Future Plate Movement Animation

Sea Floor Spreading

• http://www.classzone.com/books/earth_science/terc/content/visualizations/es0803/es0803page01.cfm?chapter_no=visualization

What causes plates to move?

A- Ridge push- Material from mid-ocean ridges pushes the plates

B- Convection Currents- in the mantle, molten rock rises, cools, then sinks, pushing the plates with the current

C- Slab Pull- Gravity pulls cooler, denser plates into mantle

Diagram

Plate Boundaries

• Convergent- “coming together”

• Divergent- “separating”

• Transform- “scraping past”

Convergent Boundaries

• There are 3 types:– Continental-Continental– Continental-Oceanic– Oceanic-Oceanic

Continental-Continental Collisions

• Responsible for creating…

– continental mountain ranges• Examples:

– Himalayas – The Alps

Continental-Continental CollisionsDIAGRAM

Convergent boundary

MANTLE

(Asthenosphere)

Mountain Range

2 converging continental plates

2 converging continental plates

Continental-Oceanic Collisions

• Also called a Subduction zone

• Responsible for creating…– Volcano ranges– Oceanic Trenches (write this in)

• Example:– Cascade Range (WA and OR)– Andes mountains

Continental-Oceanic CollisionsDiagram

Continental CrustOceanic Plate

MANTLE

(Asthenosphere)

Trench

Convergent boundary-subduction zone-

The Andes Mountains

Trench

Oceanic-Oceanic Collisions

• Responsible for creating…– Volcanic Island Chains – Oceanic Trenches

• Examples-– Japan, The Phillipines– Mariana Trench in the Pacific Ocean

Oceanic-Oceanic CollisionsDiagram

Oceanic Plate Oceanic Plate

Trench

MANTLE

(Asthenosphere)

http://www.platetectonics.com/book/images/Convergence2.gif

http://www.dkimages.com/discover/previews/875/20120887.JPG

Mariana Trench-

http://upload.wikimedia.org/wikipedia/commons/1/13/Mariana_trench_location.jpg

Divergent Boundaries

“When plates go their separate ways…”

Divergent Boundaries

• Occur when two tectonic plates separate from each other

• Responsible for– Sea-floor spreading – Mid-ocean ridges– Rift valley (on land)

• Examples: Mid-Atlantic Ridge (oceanic); Great Rift Valley (E. Africa)

Divergent Boundary

Diagram

MANTLE(Asthenosphere)

PLATE PLATE

Parting is such sweet sorrow…

Divergent boundary-Two plates move apart-

Animationhttp://www2.nature.nps.gov/GEOLOGY/usgsnps/animate/A48.gif

Mid-Atlantic Ridge

Great Rift Valley

earth.imagico.de/views/eafrica_large.jpg

Transform Boundaries

“friction never felt so good”

(unless you live in California)

Transform Boundary

• Occur when two tectonic plates scrape past each other horizontally

• Responsible for most earthquakes – Earthquakes can occur at any plate boundary

• Example: San Andreas Fault, CA

Transform BoundaryDiagram

San Andreas Fault, CA

http://nationalatlas.gov/articles/geology/features/images/sanandreas.jpg

http://pubs.usgs.gov/gip/dynamic/graphics/San_Andreas.gif

Wrapping Up

• http://www.classzone.com/books/earth_science/terc/content/visualizations/es0804/es0804page01.cfm?chapter_no=visualization