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Transcript of Earth Science
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