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LEQ: What is sea floor spreading, and what evidence exists to support the hypothesis?

LEQ: What is sea floor spreading, and what evidence exists to support the hypothesis?. Key Terms: mid ocean ridge, sea floor spreading, core samples. Mid Ocean Ridge Review. Turn to page 81 in your textbook. Discovered by using sonar during the 20 th century.

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LEQ: What is sea floor spreading, and what evidence exists to support the hypothesis?

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  1. LEQ: What is sea floor spreading, and what evidence exists to support the hypothesis? Key Terms: mid ocean ridge, sea floor spreading, core samples

  2. Mid Ocean Ridge Review • Turn to page 81 in your textbook. • Discovered by using sonar during the 20th century. • Find the mid ocean ridge that bisects the Atlantic Ocean. • Lets look at the GIS.

  3. Mid Ocean Ridge

  4. Sea Floor Spreading • Turn to page 82 in the your textbook. • Sea Floor Spreading: • A concept proposed by American geologist Mr. Harry Hess. • Mr. Hess proposed at the mid ocean ridge: • Molten material rises from the mantle and erupts. • The molten material then spreads out on both sides of the mid ocean ridge. • As the molten material spreads out, it pushes older rock to both sides of the ridge. • Lets look at the animation . • Evidence that supports the theory of Sea Floor Spreading: • Evidence from ocean material. • Evidence from magnetic stripes. • Evidence from drilling samples.

  5. What is a drilling or core Sample? • A sample of rock, soil, snow, or ice obtained by driving a hollow tube into the undisturbed medium and withdrawing it with its contained sample or core. • Core samples were taken from all over the sea floor. Core samples were returned to the surface where they were studied. • The age (how old or how long ago it was formed) of the rock can be determined from the core sample.

  6. Visual Evidence for Sea Floor Spreading • First, observe and manipulate the on line interactive activity. • Next, lets observe a GIS map of the sea floor age at the mid ocean ridge.

  7. Mid Ocean Ridge Map of the Sea Floor Age

  8. Visual Evidence Thought Questions. • Is the age of the sea floor younger or older close to the mid ocean ridge? • Is the age of the sea floor younger or older farther away from the mid ocean ridge? • On either side of the mid ocean ridge are the sea floor ages random, or do you see a pattern? • Describe the pattern you observe.

  9. Is the Earth Getting Bigger? • If the sea floor is spreading, why isn’t the Earth getting bigger? (of course not) • In our next lesson we’ll find out why!

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