key terms: mid ocean ridge, sea floor spreading, core samples
TRANSCRIPT
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 20th
century.Find the mid ocean ridge that bisects the
Atlantic Ocean.Lets look at the GIS.
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Mid Ocean Ridge
Sea Floor SpreadingTurn 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.
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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.
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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.
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Mid Ocean Ridge
Map of theSea Floor Age
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.
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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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