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Transcript
Name: Date: Period: Type of Evidence Physical Proof Through OBSERVATIONS Parsons, 2009 PROBLEM In 1947, seismologists on the U.S. research ship Atlantis found that the sediment layer on the floor of the Atlantic was much thinner than originally thought. PRIOR BELIEF IN 1947 Scientists had previously believed that the oceans have existed for about 4.5 billion years, so therefore the sediment layer should have been very thick. Copy and complete the following “If…then” statement based on what scientists believed in 1947: If Earth’s rocks have been proven to be about 4.5 billion years old, then _______________________. In the 1960’s, technology allowed scientists to take pictures with the help of a submersible called ALVIN. It could withstand crushing pressures up to 4 kilometers. Scientists discovered…. …there are lines of cracks on Earth’s ocean floor that resembles the shape of lines on a baseball! Please open your textbook and read 199-201. Type of Evidence “NEW” Rocks What rock is most abundantly formed from an a crack in an ocean? Physical Proof Through OBSERVATIONS In the 1960’s, scientists rock discovered that new _____ was being formed at the bottom of Earth’s oceans through cracks Scientists discovered strange rocks shaped like pillows because the molten material is squeezed through the crack like from a tube of toothpaste! Type of Evidence Magnetic Stripes We can test magnetic directions because opposites attract! Physical Proof Through OBSERVATIONS We know that Earth magnet behaves like a _______ with a north pole and a south pole. Scientists believe that every 780,000 years, the North and South poles REVERSE! Let’s see how the ocean floor spreads… Seafloor Spreading Lab Type of Evidence Drilling Samples Why does rock get ‘older’ as it gets farther from a ridge? Physical Proof Through OBSERVATIONS In 1968, the Glomar Challenger, a drilling ship was designed to drill in the ocean floor. We discovered that the newer rock is located closest to the mid-ocean ________ ridge. Glomar Challenger Lastly, let’s discuss SUBDUCTION… Trust me! This is very interesting! Even though the Pacific ocean covers almost 1/3 of Earth, it is SHRINKING! HUH? Subduction: When two plates come together (CONVERGE), one can sink under the other into the mantle. How does that happen? So, let’s review… RESOURCES nasa.org noaa.gov usgs.gov ucmp.berkeley.edu Holt Earth Science, 2008 Prentice Hall Earth Science, 2002