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Earth Science. Plate Tectonics. Essential Question. What is the history of Plate Tectonics? What are the mechanisms?. Geosphere Use the plate tectonics theory to explain features of the earth’s surface and geological phenomena, and describe evidence for the plate tectonics theory. - PowerPoint PPT Presentation
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Geosphere
Use the plate tectonics theory to explain features of
the earth’s surface and geological phenomena, and describe evidence
for the plate tectonics theory.
Crust: The Earth’s Skin, outer layer
Mantle: upper part is able to flow very slowly
Core: interior at high temperature and pressure
Key conceptsEarth Composition
starryskies.com/.../Earth/ under_the_surface.html
Evidence of “continental drift”—.
•Physical fit of continents•Fossil evidence•Measurements of movement•Rock layer sequences•Glacial evidence
Key concepts
Alfred Wegener
What is the theory of continental drift?
• the idea that the continents were once all joined together in one super-continent called Pangaea and slowly moved to their current positions
http://www.abdn.ac.uk/zoohons/lecture1/img008.GIF
Shoreline Fit of the Continents
Fossil Evidence
The fossils from the exact same animals are found on continents separated by vast oceans.
Plates—continental crust, oceanic crust
Features—faults, trenches, mid-ocean ridges, folded mountains, hot spots, volcanoes
Related actions —earthquakes, volcanic activity, seafloor spreading, mountain building, convection in mantle.
Key concepts
What are the plates made of?
• Ocean plates are made of basalt.
• Continental plates are made of granite.
Divergent Plate Boundaries
Two land or ocean plates move apart in opposite directions. Magma flows to the surface between
them creating new crust.
http://www.geo.lsa.umich.edu/~crlb/COURSES/270/Lec12/spreexamples.jpeg
Subduction Zones
• An ocean plate and a continental plate hit head-on. The ocean plate subducts under the continent forming a trench. The subducting plate melts. Magma rises to the surface creating a string of volcanic mountains parallel to the shoreline.
Island Arcs
Two ocean plates hit head-on. One ocean plate is forced to subduct under the other forming an ocean trench.
The subducting plate melts. Magma rises to the surface forming a string of volcanic islands parallel to the trench.
Forces—tension, compression shearing
Key concepts
Ask a Geologist
Ask an earth scientist
How does tectonic activity affect the earth’s crust?
• Builds mountains
• Creates deep ocean trenches
• Causes earthquakes
• Create volcanoes
Ocean Trenches
http://www.nhusd.k12.ca.us/ALVE/wow/Ocean/seafloor.gif
http://www.thirteen.org/savageearth/hellscrust/assets/images/ringoffire.jpg
Recent patterns of earthquake and volcanic activities; maps showing the direction of movement of major plates and associated earthquake and volcanic activity
Compressional boundaries: folded mountains, thrust faults, trenches, lines of volcanoes (e.g. Pacific “ring of fire”)
Tensional boundaries: mid-ocean ridges, rift valleys
Shearing boundaries: lateral movement producingfaults (e.g. San Andreas Fault).
Real-world contexts:
http://www.gfz-potsdam.de/pb2/pb22/projects/mamba.html
Resources• http://www.calstatela.edu/faculty/acolvil/plates/pangaea.jpg
• http://platetectonics.pwnet.org/img/wegener.jpg
• http://home.tiscalinet.ch/biografien/images/wegener_kontinente.jpg
• http://library.thinkquest.org/17457/platetectonics/comic.jpg
• http://www.soc.soton.ac.uk/CHD/classroom@sea/carlsberg/images/fossil_correlation_lge.jpg
• http://earthobservatory.nasa.gov/Library/Giants/Wegener/Images/plate_boundaries.gif
• http://www.calstatela.edu/faculty/acolvil/plates/atlantic_profile.jpg
• http://pubs.usgs.gov/publications/graphics/Fig16.gif
• http://cps.earth.northwestern.edu/SPECTRA/IMG/basalt.png
• http://cc.usu.edu/~sharohl/granite.jpg
• http://tlacaelel.igeofcu.unam.mx/~GeoD/figs/tgondvana_ice.jpg
• http://www.physics.uc.edu/~hanson/ASTRO/LECTURENOTES/F01/Lec11/Pangaea.gif
• http://www.poleshiftprepare.com/glacial_striation.jpg
• http://www.ggs.org.ge/plates.jpg• http://earth.geol.ksu.edu/sgao/g100/plots/1008_world_volc_map.jpg• http://www.aeic.alaska.edu/Input/affiliated/doerte/personal/aleutians/
ak_map_big.jpg• http://www.4reference.net/encyclopedias/wikipedia/images/
Aleutians_aerial.jpg• http://www.avo.alaska.edu/gifs/2-3/02-95-03.jpg• http://www.soc.soton.ac.uk/CHD/classroom@sea/carlsberg/images/
island_arc.jpg• http://nte-serveur.univ-lyon1.fr/nte/geosciences/geodyn_int/tectonique2/
himalaya/images/Fig5a_inde.gif• http://terra.kueps.kyoto-u.ac.jp/~sake/himalaya.jpg• http://www.andes.org.uk/peak-info-5000/sabancaya.jpg• http://www-step.kugi.kyoto-u.ac.jp/~keizo/photos/andes.JPG• http://www.letus.northwestern.edu/projects/esp/top10/andespage/
andesphysical.jpg
• http://www.soc.soton.ac.uk/CHD/classroom@sea/carlsberg/images/atlantic_tectonics%20.jpg