Evidence for a Changing Earth PART 1

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Evidence for a Changing EarthPART 1

• Chapter 1 Section 3
• Drifting Continents

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How does the earth change?

• http//science.discovery.com/tv-shows/greatest-dis
  coveries/videos/100-greatest-discoveries-continent
  al-drift.htm
• video by Bill Nye 100 Greatest Discoveries.

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Wegeners Pangaea
http//www.platetectonics.com/book/page_7.asp
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Evidence for Continental Drift

• Glossopteris fossils- woody fern-like trees from
  250 million years ago. Found across continents.

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Evidence for Continental Drift

• Lystrosaurus fossils-(meaning "shovel lizard")
  Lystrosaurus was a heavily-built, mammal like
  reptile with a short, stubby tail. Instead of
  teeth it had two tusk-like fangs made of horn. It
  was a plant-eater about 3 feet (1 m) long and
  about 200 pounds. It lived in herds near lakes
  and swamps. Since fossils of Lystrosaurus had
  been found in South Africa, India, Europe, and
  Asia, finding Lystrosaurus fossils in Antartica
  was further evidence that the continents were
  once connected into one large continent.

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Lystrosaurus
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Evidence for Continental Drift

• Mesosaurus fossils- Wegener found Mesosaurus
  fossils in Africa and South America. It was a
  major piece of evidence to support his theory of
  continental drift. Since the Mesosaurus was a
  fresh water reptile, there was no way it could
  have swam across the Atlantic Ocean (which has
  salt water) to both continents. So it provided
  evidence that Africa and South America were at
  one point joined together.http//wiki.answers.com
  /Q/Where_did_Alfred_wegener_find_fossils_of_mesosa
  urusixzz1aVA2RgLd

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Mesosaurus
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Continental Drift

• http//www.youtube.com/watch?vWaUk94AdXPAfeature
  related
• http//www.youtube.com/watch?vCm5giPd5Uro
• In 1910, Alfred Wegener proposed the theory of
  continental drift. He believed that the
  continents were drifting apart. He found evidence
  to prove his theory. But he could not answer one
  question. How were the continents moving? He
  thought they were plowing through the ocean
  crust. Other scientists knew this could not
  happen and so discredited his theory.
• http//wgvu.pbslearningmedia.org/resource/ess05.sc
  i.ess.earthsys.wegener1/plate-tectonics-the-scient
  ist-behind-the-theory/Historical snapshot about
  Alfred Wegener.

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Three pieces of Evidence for Continental Drift
Theory

• 1.
• 2.
• 3.

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Alfred Wegener Song By The Amoeba People

• http//www.youtube.com/watch?vT1-cES1Ektofeature
  related

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Evidence for a Changing EarthPART 2

• Chapter 1 Section 4
• Sea-floor Spreading

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Sea-floor Spreading

• In the 1960's scientists finally found what was
  missing in Wegener's theory. Geologist Harry Hess
  finally found evidence that Wegener was right
  when mountains were discovered at the bottom of
  the ocean. Hess proposed his theory of sea-floor
  spreading as the answer to the mystery of
  continental drift. 

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Discovery of Underwater Mountains

•  The mid-ocean ridge is found throughout the
  oceans of the earth. This is a 50,000 mile chain
  of volcanic mountains in the middle of the ocean.
  
• These mountains have a deep crack that runs
  through them. It is called a rift valley.
• Sea-floor spreading happens here as molten magma
  from the mantle oozes up and forms new ocean
  floor spreading the plates apart. It is a slow,
  regular process. There are no explosive bursts
  like volcanic eruptions on land.

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Mid-Ocean Ridge

• Sea Floor Spreading with Bill Nye
• http//www.youtube.com/watch?vGyMLlLxbfa4feature
  related

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Evidence for Sea-floor Spreading

• During WWII Geologist Harry Hess worked on a
  ship that had sonar. They mapped the ocean floor
  and discovered the Mid-Atlantic Ridge. Prior to
  this all scientists believed the Oceans floor was
  flat and barren.

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Evidence for Sea-floor Spreading

• The mid-ocean ridges occur along plate boundaries
  that are separating (diverging).
• Rocks that form from molten rock , called Pillow
  Lava were discovered along the mid-ocean ridge
  by the submersible submarine named Alvin.

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Evidence for Sea-floor Spreading

• Core samples drilled and collected from the
  Atlantic ocean floor showed that the sediment was
  thinner near the mid-ocean ridges and the age of
  the rock was younger meaning the ocean floor was
  younger at the mid-ocean ridge.

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Core Sampling Model

• Use the straw at your groups station and
  carefully push it down into the cup on your
  table. ONLY ONE TIME! BE CAREFUL. DO NOT TIP
  OVER!!
• Put your finger over the top and very gently and
  slowly pull up a core sample.
• Each person should draw a diagram of your sample.
  
• Question What did scientists learn from core
  samples to support the theory of sea-floor
  spreading?

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Evidence for Sea-floor Spreading

• Those core samples also showed a record of
  magnetic reversals. The rocks particles were
  aligned differently as you moved out away from
  the mid-ocean ridge on either side showing a
  pattern of changes.

http//mail.colonial.net/hkaiter/ContinentalDrift
.html
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Mid Ocean Ridge Formation
http//www.mysciencebox.org/files/images/seafloor_
animation.gif
http//wgvu.pbslearningmedia.org/resource/ess05.sc
i.ess.earthsys.wegener2/plate-tectonics-further-ev
idence/ WATCH THIS!
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Evidence for a Changing EarthPART 3

• Chapter 1 Section 5
• Plate Tectonics
• http//wgvu.pbslearningmedia.org/resource/ess05.sc
  i.ess.earthsys.plateintro/plate-tectonics-an-intro
  duction/ 
• http//wgvu.pbslearningmedia.org/resource/ess05.sc
  i.ess.earthsys.boundaries/tectonic-plates-and-plat
  e-boundaries/ Look at the plates!

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Lithospheric Plates of the Earth

• The Earths lithosphere is broken into plates
  that are constantly moving and changing the
  surface of the Earth.

http//dreamtigers.wordpress.com/2011/05/11/plate-
tectonic-metaphor-illustrations-cmu/
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The Major PlatesList the names of the plates
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2-D Earth 3-D Earth

• Looking at the Earth from a 2-D map can be
  misconceiving. Check out the site below!
• http//www.classzone.com/books/earth_science/terc/
  content/investigations/es0301/es0301page03.cfm

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What is Plate Tectonics?

• The term plate tectonics refers to how the
  Earth's surface is made up of plates. In geology,
  a plate is a large slab of rock, while tectonics
  is a word of Greek origin meaning "to build.
• Plate Tectonics is the current theory that
  explains how the surface of the Earth is broken
  into plates that are slowly but constantly
  forming, subducting and changing to create the
  features of the Earths surface.

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Evidence for Plate Tectonics

• The theories of continental drift and sea-floor
  spreading gave a basis for the discovery of the
  plates. However further evidence from the
  locations of earthquakes and volcanoes helped to
  map their boundaries.

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Evidence for Plate Tectonics
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TIME LINE FOR THE DEVELOPMENT OF THE THEORY OF
PLATE TECTONICS

• http//www.britannica.com/EBchecked/topic/463912/p
  late-tectonics/301055/Time-line-of-the-development
  -of-the-theory-of-plate-tectonics
• Have to join to see this! UGH!

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How do the Plates Move?

• Geologists believe that convection currents in
  the mantle provide the force that moves the
  plates.
• http//www.windows2universe.org/earth/interior/how
  _plates_move.html How do the plates move?
• http//www.youtube.com/watch?vctoMRrUwBwI New
  evidence for movement of the plates. Time 115

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Movement of the Plates

• How do scientist know that the continents are
  moving today?
• http//www.pbs.org/wgbh/nova/ice/continents/
• Have you ever rode bumper cars? The plates are
  moving around like this crashing into each other,
  moving away from each other, or sliding past each
  other. They all move at different speeds,
  anywhere from a couple of millimeters to several
  centimeters per year. Overall they move very
  slowly. The place where the two plates meet is
  called a plate boundary. There are three types of
  boundaries. Faults occur along these boundaries
  where the crust slips and fractures.

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Diverging Plate Boundaries

• Diverging boundaries occur where plates are
  pulling apart. The mid-ocean ridge is the most
  common divergent boundary. A rift valley forms
  where these occur on land.

http//wdict.net/word/divergentboundary/
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The Great Rift Valley

• The plates can separate across a continent too!

http//seeker401.files.wordpress.com/2011/01/image
004.jpg
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The Earths Surface Separates
http//science.discovery.com/tv-shows/when-earth-e
rupts/videos/african-rift.htm watch this series
of 4 short videos about the rift valley.
http//www.sciencephoto.com/media/167053/enlarge
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Converging Plate Boundaries

• http//www.pbs.org/wgbh/nova/everest/earth/shock.h
  tml
• Watch this to see how the Himalayan Mountains
  are forming.
• Converging boundaries can occur where two
  continents are smashing into one another and form
  mountains.

http//dreamtigers.wordpress.com/2011/05/11/plate-
tectonic-metaphor-illustrations-cmu/
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Converging Plate Boundaries

• Converging plates also occur at subduction zones
  where the ocean plates dive below the continents
  forming deep-ocean trenches.

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Transform Plate Boundaries

• Transform boundaries happen where plates are
  sliding past each other. One of the most famous
  is in California, the San Andreas fault, where
  the edge of California is shearing off to the
  North.

http//www.cotf.edu/ete/modules/msese/earthsysflr/
plates1.html
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Hot Spots

• Hot Spots are places where the Mantle reaches up
  close to the surface of the crust either near
  boundaries or in the center of plates. The
  Hawaiian Islands are formed this way, as well as
  places like Yellowstone National Park.
• http//www.geology.sdsu.edu/how_volcanoes_work/int
  raplvolc_page.html What are hot spots?

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Hot Spots around the Earth
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The Search for New Evidence Continues!

• Trip to the bottom of the Mariana Trench, the
  deepest place in our oceans.
• http//en.wikipedia.org/wiki/Mariana_Trench
  Information here.
• http//www.youtube.com/watch?vY2tm40uMhDI
• Time 205 Released March 2012 National
  Geographic
• http//www.youtube.com/watch?vRxUZM-cLtGgfeature
  player_embedded Video from Oct. 2011 showing
  jellyfish at bottom of trench and
  Xenophyophores,giant single-celled sea creatures
  that can be 4 inches wide.

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Life at the bottom of a Mid-ocean Ridge

• http//wgvu.pbslearningmedia.org/resource/tdc02.sc
  i.ess.earthsys.deepseavents/deep-sea-vents-and-lif
  es-origins/ Deep Sea Vents and Lifes
  OriginsTime 4 min.
• http//wgvu.pbslearningmedia.org/resource/nsn09.sc
  i.life.eco.seafloor/exploring-the-arctic-seafloor/
  Exploring the Arctic sea floor.
• http//wgvu.pbslearningmedia.org/resource/ipy09.sc
  i.life.eco.scini/studying-the-antarctic-sea-floor/
  Exploring the Antarctic sea floor using a ROV
  called SCINI.