CSTC+1.4

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1.4 Sea-Floor Spreading
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Vocabulary
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 * Mid-Ocean Ridge**- the longest chain of mountains in the world
 * Sonar**- a device that bounces sound waves off underwater object
 * Sea-Floor Spreading**- a process that continually adds new material to the ocean floor
 * Deep-Ocean Trenches**- the ocean floor plunges into deep underwater canyons
 * Subduction**- the process by which the ocean floor sinks beneath a deep-ocean trench and back into the mantle

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= = -the longest chain of mountains in the world -in the mid 1900, scientists mapped the mid-ocean ridge -curces like the seam of a baseball along the sea floor -Iceland is part of the mid-ocean ridge
 * Mapping the Mid-Ocean Ridge**

Evidence for Sea-Floor Spreading -the mid-ocean ridge forms a crack in the ocean crust -molten material com out and the older rocks move aside -three evidences, evidence from molten material, evidence from magnetic stripes, evidence from drilling samples

-pushing the ocean floor down -convection
 * Subduction at Deep-Ocean Trenches**

-subduction could change size of oceans -subduction in the Pacific Ocean -subduction in the Atlantic Ocean
 * Subduction and Earth's Oceans**