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Transcript
926 Review SFS and CD.notebook October 04, 2011 Good Morning! October 4, 2011 1. Please paste your Science Energizer slip into your journal! 2. Answer the question and explain WHY you chose your answer. Mary decides to conduct a study of local weather patterns for school. Mary's teacher wants her to turn in detailed and accurate notes as well as her results and conclusion. Why would it be important to include Mary's notes? A. The conclusion of Mary's study will not make sense without the notes. B. Mary's teacher can use the notes to examine Mary's knowledge of the local weather patterns. C. The notes provide a way to understand Mary's hypothesis. D. Mary's teacher needs the notes to make sure Mary's study was conducted following the scientific method. 1 926 Review SFS and CD.notebook October 04, 2011 Current Events in Science Each group will read an article, answer questions, and then share with the class. 1. First, read individually. 2. Answer the questions. 3. Collaborate with your team. Be prepared to share! Class Discussion Article 1 you lead. Select a person to be the spokesperson. This person will talk about the 2 sentences summary and their questions with answers. While they are talking, listening carefully and fill in the answer the questions from each article. You will turn it in when you're done. This will be a grade. 2 926 Review SFS and CD.notebook October 04, 2011 Reviewing Continental Drift and Sea-Floor Spreading 1. Get out your notes for Continental Drift and Sea-Floor Spreading. 2. Turn your listening ears on! 3. Ask questions if you are confused. Alfred Wegener's hypothesis was that all the continents were once joined together in a single landmass and have since drifted apart. continental drift-the hypothesis that the continents slowly move across Earth's surface. 3 926 Review SFS and CD.notebook October 04, 2011 Evidence from Land Features When he pieced together maps of Africa and South America, he noticed that mountain ranges on both continents line up. He also noticed that coal fields in Europe matched up with similar ones in North America. Evidence from Fossils An example is Glossopteris, a fernlike plant that lived 250 million years ago. These fossils have been found in rocks in Africa, South America, Australia, India, and Antarctica. 4 926 Review SFS and CD.notebook October 04, 2011 Other fossil examples include the fresh water reptiles Mesosaurus and Lystrosaurus. These fossils were found in areas that are now separated by oceans and neither could have swum great distances across salt water. Wegener inferred that these reptiles had to have lived on one large land mass. Evidence from Climate As a continent moves closer to the equator it becomes hotter and as it moves away, colder. But continents carry with them the fossils and rocks formed at the previous locations. 5 926 Review SFS and CD.notebook October 04, 2011 Deep scratches in rocks showed that continental glaciers once covered South Africa. The climate of South Africa is too mild today for continental glaciers to form. Wegener concluded that when Pangaea existed, South Africa was much closer to the South Pole. mid-ocean ridge an undersea mountain chain where new ocean floor is produced, it is a divergent plate boundary divergent boundary a plate boundary where two plates move away from each other 6 926 Review SFS and CD.notebook October 04, 2011 Harry Hess proposed in 1960 that the movement of the continents was a result of sea-floor spreading. Sea-floor spreading • The sea floor spreads apart along both sides of a mid-ocean ridge as new crust is added • As a result, the ocean floors move like conveyor belts, carrying the continents along with them 7 926 Review SFS and CD.notebook October 04, 2011 1. Sea-floor spreading begins at a mid-ocean ridge, which forms along a crack in the ocean crust. 2. Along the ridge, molten material that forms several kilometers beneath the surface rises and erupts. 3. At the same time, older rock moves outward on both sides of the ridge. 4. As the molten material cools, it forms a strip of solid rock in the center of the ridge. 5. When more molten material flows into the crack, it forms a new strip of rock. 8 926 Review SFS and CD.notebook October 04, 2011 What are the pieces of evidence for SeaFloor Spreading? 1. Molten Material 2. Magnetic Stripes 3. Drilling Samples Evidence from Molten Material Scientists found rocks that were shaped like pillows or like toothpaste squeezed from a tube. These rocks only form when molten material hardens quickly after erupting under water. These rocks showed that molten material has erupted again and again along the midocean ridge. 9 926 Review SFS and CD.notebook October 04, 2011 Evidence from Magnetic Stripes Earth's magnetic poles have reversed themselves many times during Earth's history. Scientists discovered that the rock that makes up the ocean floor lies in a pattern of magnetized stripes. The stripes hold a record of reversals in Earth's magnetic field. Evidence from Drilling Samples Rock samples were collected in 1968 from a drilling ship called the Glomar Challenger. Scientists determined the age of the rocks and they found that the farther away from a ridge the samples were taken, the older the rocks were. The youngest rocks were always in the center of the ridges. 10 926 Review SFS and CD.notebook October 04, 2011 If new oceanic lithosphere is created at mid-ocean ridges, where does it go? Subduction when oceanic crust sinks beneath a deep-ocean trench and back into the mantle at a convergent plate boundary Continental Drift Sea-Floor Spreading 11 926 Review SFS and CD.notebook October 04, 2011 Continental Drift Sea-floor Spreading 12 926 Review SFS and CD.notebook October 04, 2011 13