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Chapter 10.1 Continental Drift

Continental drift is the _______________ that states that the continents once formed a single __________________, broke up, and ____________ to their present locations.

Alfred _________ thought that all the separate continents of today were once joined in a single landmass that he called _______________. Continental drift _______________ many puzzling observations, including why _________________ of the same plant and animal _________________ are found on both ______________ of the Atlantic Ocean.

Write the letter of the best answer on the line provided for each picture.

Continental Drift is a theory that proposes that continents can drift apart from each other and have done so in the past.

_____________________ _____________________

Matching

A. Gradually Pangaea broke into two pieces Gondwanda and Laurasia. By 180 MYA the north atlantic and the idian ocean began to form.

B. 245 Million Years Ago today’s continents were part of one giant land mass called Pangaea. A giant sea called Panthalassa surrounded Pangaea.

C. Today the continents continue to move at a rate of about one to ten centimeters a year The Atlantic Ocean is getting larger and the pacific ocean is getting smaller

D. By 65 mya Laurasia and Gondwana had broken into smaller pieces and the south atlantic ocean began forming._____________________ _____________________

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Sea Floor SpreadingSea-floor spreading is the ________________ by which new oceanic ________________ forms as magma rises toward

the surface and _________________ where two tectonic plates pull ________________ from each other; sea-floor

spreading occurs at mid-ocean _________________.

Number these statements from the first event to the last.

_________ A. New lithosphere begins to appear and fill the gap between the plates and creates a mid ocean ridge.

_________ B. When tectonic plates push apart, magma from the asthenosphere pushes it’s way to the surface of the earth and begins to create a mid ocean ridge.

_________ C. The older crust gets pushed further away from the mid ocean ridge while the youngest crust is always along the mid ocean ridge.

_________ D. Magma continues to come from the asthenosphere and more crust is deposited on the sea floor.

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Magnetic ReversalsMagnetic reversal is the __________________ by which the Earth's north and south magnetic __________________ periodically change ________________.

The _________________ of magnetic reversals on the ______________ ____________________ is __________________ of sea-floor spreading.

Match each picture with its description.

A. This represents today’s magnetic field.

B. This represents a magnetic reversal from today’s present magnetic field.

Write a brief explanation of this picture.

Circle the picture that accurately depicts how polar reversals are recorded at the Mid Atlantic Ridge confirming the theory of sea floor spreading?

Explain why you chose this answer.