Plate Tectonics Objectives • 4a. Compare and contrast the relative positions and components of the Earth’s crust (e.g. mantle, liquid and solid core, continental crust, oceanic crust). (DOK 1) • 4b. Draw conclusions about historical processes that contribute to the shaping of planet Earth. (DOK 3) – Movements of the continents through time – Continental plates, subduction zones, trenches, etc. The Earth’s Surface • The Earth's rocky outer crust solidified billions of years ago, soon after the Earth formed. • It is not a solid shell • It is broken up into huge, thick plates that drift on top of the soft, underlying mantle. The Crust • Outermost layer • 20-50 miles thick on continents • 5-10 miles thick in the ocean • Made of Oxygen, Silicon, Aluminum The Mantle The Mohorovicic discontinuity is the layer • Layer of Earth between the Earth’s crust and mantle. between the crust and the core • Contains most of the Earth’s mass • Has more magnesium and less aluminum and silicon than the crust • Is denser than the crust The Core • Below the mantle and to the center of the Earth • Mostly Iron, smaller amounts of Nickel, almost no Oxygen, Silicon, Aluminum, or Magnesium The Formation of Earth’s Core http://www.learn360.com/ShowVideo.aspx?ID=350588 Plate Tectonics…Background Plate Tectonics • Greek – “tektonikos” of a builder • Pieces of the lithosphere that move around • Each plate has a name • Fit together like jigsaw puzzles • Float on top of mantle similar to ice cubes in a bowl of water Tectonic Plates • Alfred Wegener 1900’s Continental Drift Continents were once a single land mass that drifted apart. • Fossils of the same plants and animals are found on different continents • Called this supercontinent Pangea - Greek for “all Earth” • 245 Million years ago • Split again 180 million years ago http://members.enchantedlearning.com/subjects/astronomy/planets/earth/Continents.shtml Continental Drift Theory http://www.learn360.com/ShowVideo.aspx?ID=140062 Evidence of Pangea Sea Floor Spreading Sea Floor Spreading • Mid Ocean Ridges – underwater mountain chains that run through the Earth’s Basins • Magma rises to the surface, solidifies and new crust forms • Older Crust is pushed farther away from the ridge How Plates Move http://pubs.usgs.gov/gip/dynamic/unanswered.html Different Types of Boundaries http://pubs.usgs.gov/gip/dynamic/understanding.html Three Types of Plate Boundaries • Divergent • Convergent • Transform Divergent Boundary • A tectonic boundary where two plates are moving away from each other • New crust forms from magma that rises to the Earth's surface between the two plates. Examples: Red Sea and the mid-ocean ridge (running the length of the Atlantic Ocean) http://www.learn360.com/ShowVideo.aspx?ID=146490 Continental Divergent Boundary http://www.geology.com Divergent Continental Boundary – Arabian and African Plates Oceanic Divergent Boundary http://www.geology.com Divergent Oceanic Boundary – Iceland http://pubs.usgs.gov/gip/dynamic/understanding.html Convergent Boundary • A tectonic boundary where two plates are moving toward each other. Examples: western coast of South America and the Himalayan Mountains Convergent Continental Boundary – Indian and Eurasian Plates Convergent Boundary – Oceanic & Continental http://pubs.usgs.gov/gip/dynamic/understanding.html & http://www.geology.com Convergent Boundary – Oceanic & Oceanic http://pubs.usgs.gov/gip/dynamic/understanding.html & http://www.geology.com Convergent Boundaries - Continental http://pubs.usgs.gov/gip/dynamic/understanding.html & http://www.geology.com Transform Boundary • found where two continental plates slide past each other in the opposite direction, while connecting two divergent or convergent plate boundaries. Example: San Andreas Fault in Western California Plate Tectonics http://www.learn360.com/ShowVideo.aspx?ID=132025 Transform Boundary – San Andreas Fault www.geology.com Review • Name the 4 main layers of the Earth. • What is a tectonic plate? • What is the Continental Drift Theory and who founded the idea? • What was Pangea? • What is Sea-Floor spreading? • Name the three different types of plate boundaries and one location on Earth for each one. Citations • The Location of Earth's Tectonic Plates. Distribution Access Inc. 1999 Learn360. 18 November 2013 http://www.learn360.com/ShowVideo.aspx?ID=146929 • Formation of Earth's Core. A&E Television Networks. 2007 Learn360. 18 November 2013 http://www.learn360.com/ShowVideo.aspx?ID=350588 • Plate Tectonics. Distribution Access Inc. 1999 Learn360. 18 November 2013 http://www.learn360.com/ShowVideo.aspx?ID=132025 • Volcano's. Educational Activities. 1992 Learn360. 18 November 2013 http://www.learn360.com/ShowVideo.aspx?ID=146490 • Continental Drift Theory. VEA. 2006 Learn360. 18 November 2013 http://www.learn360.com/ShowVideo.aspx?ID=140062 .