plate tectonics

Plate TectonicsLiz LaRosa for use with my 5th Grade Science Class

http://www.middleschoolscience.com 2009

Earth’s Layers1.Scientists determined the inner layers using seismic waves.2.Earth’s crust is broken up into huge tectonic plates (lithosphere) that drift atop the soft, putty-like underlying middle mantle (asthenosphere).The lithosphere is made up of crust and upper mantle.

The Mantle

• Thickest layer

• Contains most of the Earth’s mass

• Is denser than the crust

http://pubs.usgs.gov/gip/dynamic/unanswered.html

Plate movement is caused by convection currents in the asthenosphere.

The Core• Both inner and outer

core are made of hot metals.

• The inner core is solid.

• The outer core is liquid.

Tectonic Plates

Plates can move in three directions.

• Together- Convergent boundary

• Apart- Divergent boundary

• Past each other-Transform boundary

Different Types of Boundaries

http://pubs.usgs.gov/gip/dynamic/understanding.html

Continental-Continental collisionex: Indian and Eurasian Plates result in non-

volcanic continental mountains-the Himalayan Mountains

Indian Plate

Eurasian Plate

Sea Floor Spreading- Divergent boundaries

Sea Floor Spreading

• Mid Ocean Ridges – underwater mountain chains that run through the Earth’s Basins

• Magma rises to the surface and solidifies and new crust forms

• Older Crust is pushedfarther away from the ridge

Divergent Boundary – Arabian and African Plates

Arabian Plate

African PlateRed Sea

Divergent Boundary – Iceland

http://pubs.usgs.gov/gip/dynamic/understanding.html

Convergent Boundary – Oceanic & ContinentalThis is called a Subduction Zone because the ocean plate is sinking under the continental.

http://pubs.usgs.gov/gip/dynamic/understanding.html & http://www.geology.com

Denser basalt

Less dense granite

At subduction zones of continental and oceanic crust there are many

volcanoes( a volcanic arc) and trenches due to the more dense

ocean plate sinking.

www.geology.com

Transform Boundary – San Andreas FaultAt this boundary, crust is neither created or

destroyed.Many earthquakes occur at all plate boundaries.