Earth Science and M.E.A.P

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Earth Science and M.E.A.P

• The benchmarks and you!

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EG. Geosphere Benchmark 2 Use the plate
tectonics theory to explain features of the
earths surface and geological phenomena, and
describe evidence for the plate tectonics
theory.
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Key concepts
Earth Composition
CrustMantle upper part is able to flow very
slowly Core interior at high temperature and
pressure
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starryskies.com/.../Earth/ under_the_surface.html
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Key concepts

• Evidence of continental drift
• .
• Physical fit of continents
• Fossil evidence
• Measurements of movement
• Rock layer sequences
• Glacial evidence

Alfred Wegener
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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

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http//wrgis.wr.usgs.gov/docs/parks/animate/A08.gi
f
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• What evidence supports the theory of continental
  drift?

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Shoreline Fit of the Continents
http//www.abdn.ac.uk/zoohons/lecture1/img008.GIF
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Fossil Evidence

• The fossils from the exact same animals are found
  on continents separated by vast oceans.

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Matching Rock Layers
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Glacier Evidence
Glaciers scars are found on continents which are
today too warm for glaciers.
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How fast are the plates moving?
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Bell Ringer

• Why are the continents moving?

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• During WWI scientists used sound waves to detect
  submarines and discovered underwater systems of
  ridges and valleys like those found on the
  continents.

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Seafloor spreading is Hesss theory that new
seafloor is formed when magma is forced upward
toward the surface at a mid-ocean ridge.
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Seafloor Spreading
The oceans are widening along the mid-ocean
ridges.
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Volcanoes located along ocean ridges erupt,
creating new ocean floor.
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Evidence for spreading

• In 1968, scientists aboard the research ship
  Glomar Challenger began gathering information
  about the rocks on the seafloor. They found that
  the youngest rocks are located at the mid-ocean
  ridges.

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Key concepts
Platescontinental crust, oceanic crust
Featuresfaults, trenches, mid-ocean ridges,
folded mountains, hot spots, volcanoes Related
actions earthquakes, volcanic activity, seafloor
spreading, mountain building, convection in
mantle.
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The earths lithosphere is broken into huge
sections called plates that are in constant
motion.
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What are the plates made of?

• Ocean plates are made of basalt.
• Continental plates are made of granite.

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Divergent Plate Boundaries

• Two land or ocean plates move apart in
  opposite directions. Magma flows to the surface
  between them creating new crust.

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Mid-Atlantic Ridge Divergent Boundary
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http//www.geo.lsa.umich.edu/crlb/COURSES/270/Lec
12/spreexamples.jpeg
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Iceland a continent directly over the
Mid-Atlantic Ridge
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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.

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Andes Mountains

• Subduction zones form chains of volcanic
  mountains along the shoreline.

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Collision Zones

• Two continents hit head-on, crinkling up the
  land into a high mountain chain.

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Indias Collision with Asia
Himalayas
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The Himalayas Are Born
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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.

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The Aleutian Islands
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Key concepts
Forcestension, compression shearing
Ask a Geologist
Ask an earth scientist
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How does tectonic activity affect the earths
crust?

• Builds mountains
• Creates deep ocean trenches
• Causes earthquakes
• Create volcanoes

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Ocean Trenches
http//www.nhusd.k12.ca.us/ALVE/wow/Ocean/seafloor
.gif
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Volcanoes
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Most volcanoes occur at plate boundaries
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http//www.thirteen.org/savageearth/hellscrust/ass
ets/images/ringoffire.jpg
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Real-world contexts
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 producing faults (e.g. San
Andreas Fault).
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http//www.gfz-potsdam.de/pb2/pb22/projects/mamba.
html
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Resources

• http//www.calstatela.edu/faculty/acolvil/plates/p
  angaea.jpg
• http//platetectonics.pwnet.org/img/wegener.jpg
• http//home.tiscalinet.ch/biografien/images/wegene
  r_kontinente.jpg
• http//library.thinkquest.org/17457/platetectonics
  /comic.jpg
• http//www.soc.soton.ac.uk/CHD/classroom_at_sea/carls
  berg/images/fossil_correlation_lge.jpg
• http//earthobservatory.nasa.gov/Library/Giants/We
  gener/Images/plate_boundaries.gif
• http//www.calstatela.edu/faculty/acolvil/plates/a
  tlantic_profile.jpg
• http//pubs.usgs.gov/publications/graphics/Fig16.g
  if
• http//cps.earth.northwestern.edu/SPECTRA/IMG/basa
  lt.png
• http//cc.usu.edu/sharohl/granite.jpg
• http//tlacaelel.igeofcu.unam.mx/GeoD/figs/tgondv
  ana_ice.jpg
• http//www.physics.uc.edu/hanson/ASTRO/LECTURENOT
  ES/F01/Lec11/Pangaea.gif
• http//www.poleshiftprepare.com/glacial_striation.
  jpg

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• http//www.ggs.org.ge/plates.jpg
• http//earth.geol.ksu.edu/sgao/g100/plots/1008_wor
  ld_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_at_sea/carls
  berg/images/island_arc.jpg
• http//nte-serveur.univ-lyon1.fr/nte/geosciences/g
  eodyn_int/tectonique2/himalaya/images/Fig5a_inde.g
  if
• http//terra.kueps.kyoto-u.ac.jp/sake/himalaya.jp
  g
• http//www.andes.org.uk/peak-info-5000/sabancaya.j
  pg
• http//www-step.kugi.kyoto-u.ac.jp/keizo/photos/a
  ndes.JPG
• http//www.letus.northwestern.edu/projects/esp/top
  10/andespage/andesphysical.jpg
• http//www.soc.soton.ac.uk/CHD/classroom_at_sea/carls
  berg/images/atlantic_tectonics20.jpg