Plate Boundaries Where two plates meet. http://science.discovery.com/videos/100-greatest-discoveries-shorts-plate-tectonics.html http://funnel.sfsu.edu/courses/geol103/labs/seafloor/images/Plate.boundaries.gif

Recall: The lithosphere is broken into plates that “float” or “ride” on the asthenosphere. Convection in the mantle is the driving force for this movement.

There are 3 Types of Plate Boundaries… http://earthguide.ucsd.edu/eoc/teachers/t_tectonics/t_tectonics.html

I. Convergent Boundaries Two plates move towards each other 3 Types: Oceanic-Oceanic Oceanic-Continental Continental-Continental http://earthguide.ucsd.edu/eoc/teachers/t_tectonics/t_tectonics.html

Complete the Table for Convergent Boundaries: Type of Boundary Convergent: Sketch of Boundary/ Direction of movement Description of boundary Deformation Formed Oceanic - Oceanic Oceanic-Continental Continental- Continental

1. Oceanic – Oceanic Convergence: One plate subducts under the other Forms Volcanoes and Volcanic Island Arches. Ex.: Japan, Philippines, West Indies http://www.eorc.jaxa.jp/en/imgdata/topics/2004/img/tp040513_01.jpg http://www.worldatlas.com/webimage/countrys/namerica/caribb/special/westind.gif

Oceanic - Oceanic Boundary:

Oceanic – Oceanic convergence Convergent Type Sketch/ Direction Description Deformation Produced Oceanic - Oceanic Oceanic plate melts as it sinks under another oceanic plate into mantle New magma rises Forms volcanoes on ocean floor May form volcanic island arc Produce earthquakes & tsunamis One oceanic plate descends beneath the other Volcanoes form on the ocean floor May eventually form volcanic island arc

2. Oceanic- Continental Convergence: Oceanic crust is denser, so it is forced under the continental crust, creating a SUBDUCTION ZONE Oceanic always subducts under continental Example: Andes Mountains in western South America

Oceanic-Continental Boundary http://images.iop.org/objects/phw/news/11/3/10/SAplate.jpg

Oceanic – Continental convergence Convergent: Sketch/ Direction Description Deformation Produced Oceanic - Continental Oceanic plate melts as it sinks under continental plate into the mantle New magma rises Produce earthquakes & tsunamis Can form volcanic arc and/or mountains onshore Forms deep-sea trenches offshore

3. Continental - Continental convergence: Colliding edges are crumpled and uplifted Neither will Subduct Deformation: mountain ranges. (Non-Volcanic) Ex. N. America + Africa Plates = Appalachian Mtns. India + Eurasia Plates = Himalayas http://static.howstuffworks.com/gif/willow/the-himalayas0.gif

Continental/Continental Boundary

Continental-Continental convergence Convergent: Sketch/ Direction Description Deformation Produced Continental - Continental Continental plates collide Earthquakes common Forms NON-VOLCANIC mountain ranges

Fill in the Table for Divergent Boundaries Type of Boundary Divergent: Sketch of Boundary/ Direction of movement Description of boundary Example Oceanic Continental

II. Divergent boundaries: 2 plates moving apart from each other

1. Oceanic Ridge Sea floor spreading produces new lithosphere Magma rises to fill the gap as the plates separate, pushing-up on the plates, and forming a mid-oceanic ridge Example: Mid-Atlantic Ridge (Atlantic Ocean)

Oceanic Ridge (seafloor spreading)

Oceanic Ridges Ocean Elevated seafloor separating along the plate boundary Mid-Ocean Ridges 1. Mid-Atlantic Ridge

Rift Valley Magma close to the surface sinks the crust as it tries to pull it apart. Examples:

Rift Valley Divergent Continental Sketch Description Deformation: Continental Lowered area of continental crust due to magma close to the surface Continental Rift – occurs on land & eventually splits the landmass

Rift Valley

III. Transform Fault Boundaries Most located within ocean basins Some cut through continental crust Example: San Andreas Fault in California. http://pubs.usgs.gov/gip/dynamic/graphics/San_Andreas.gif

Transform Fault Boundaries Type of boundary Sketch/ Direction Description Deformation Transform Fault Two plates scrape past each other No production or destruction of the lithosphere Earthquakes or Tsunamis Fault Line

Transform Fault Boundaries ex.

Convection in the Mantle