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Consider the following statements made by two students debating why the oceanic and...

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mmmmr | Student, Undergraduate | (Level 3) eNoter

Posted March 26, 2011 at 7:02 AM via web

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Consider the following statements made by two students debating why the oceanic and continental plates move:

Student 1: The plates are moving because the mantle material is constantly moving beneath Earth’s plates, and this causes the plates to move.

Student 2: I disagree. The plates are just floating on the mantle material. The plates stared moving a long time ago when Earth initially formed and the plates’ momentum keeps them moving toward each other.

Do you agree or disagree with either or both of the students?

A. I disagree with both students

B. I agree with Student 1

C. I agree with Student 2

D. I agree with both students

1 Answer | Add Yours

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enotechris | College Teacher | (Level 2) Senior Educator

Posted May 16, 2011 at 7:21 AM (Answer #1)

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The current version of the Earth's crust dates back about 225 million years, to the time of Pangea ("all earth.")  That super continent has since broken up, and the fragments moved around the planet surface. Beneath the solid lithosphere lies the asthenosphere, a more turbulent, hot, elastic region upon which the solid masses float.  Current studies indicate that the continental masses have been subducted many times; not only are the plates moving toward each other, they have been forced under each other to re-emerge as a new land mass.  The plates are both floating and moving on the mantle material; therefore best answer is D.

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