SBSK+1.4

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Vocabulary

 * mid-ocean ridge**-undersea mountain chain where new ocean floor is produced
 * Sonar**-system that determines the distance of an object under water by recording echoes of soundwaves
 * Sea-Floor Spreading**-process in which molten material adds new oceanic crust to the ocean floor
 * deep-ocean trenches**deep ocean valley along the ocean floor through which ocean crust slowly sinks into the Mantle
 * Subduction**-oceanic crust sinks beneath the deep-ocean trench and back into the mantle at a convergent boundary

Outline
===Mapping the mid-ocean ridge===

Evidence for Sea-Floor spreading
 * mid-ocean ridge is the longest chain of mountains in the world
 * sonar is a device that bounces sound waves off under water objects and then records the echoes of these sound waves
 * Evidence from molten material
 * Evidence from Magnetic Stripes
 * Evidence from Drilling Samples

Subduction at deep-ocean trenches

 * deep-ocean trenches are deep undersea canyons
 * Subduction occurs at the deep-ocean trenches

Subduction and Earth's Oceans

 * Subduction in the Pacific Ocean
 * Subduction in the Atlantic Ocean