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Name: Nick
Status: Educator
Age: 30s
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Understanding the law of heat transfer that heat moves towards a cooler region until both reach equilibrium, how is it that the Earth's thin skin of crust (average of 6 miles thick compared to Earth's diameter of 7,926 miles) can keep the Earth's oceans cool? (If the Earth were a meter in diameter the crust would be a skin of less than a millimeter). The Ocean's temperature gets cooler the deeper you go not warmer: How can the Earth's magma interior of 7,920 miles be over 2,000 F and not heat the oceans?

Good question. The key lies in two facts: the ocean is liquid, and water (above 4 Celsius) is less dense as its temperature increases. This allows cold water to sink to the bottom. In the earth's crust, temperature increases with depth because this convective transport can't take place.

Richard E. Barrans Jr., Ph.D.
Assistant Director
PG Research Foundation, Darien, Illinois

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