MLEG1.4

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vocabulary
mid-ocean ridge: undersea mountain chain where new ocean floor is produced; a divergent plate boundary sonar: system that determines the distance of an object under water by recording echo of sound waves; gets its name from sound navigation and ranging sea-floor spreading: process by which molten material adds new oceanic crust to the ocean floor deep-ocean trenches: deep valley along the ocean floor through which oceanic crust slowly sinks through mantle subduction: process by which oceanic crust sinks beneath a deep ocean trench and back into the mantle at an convergent plate boundary

Outline:
Mapping the Mid-Ocean Ridge East Pacific Rise= one part Longest chain of mountains Scientists use sonar for Mid-Ocean Ridge Evidence for sea-floor spreading: Continents moving Movement starting at the mid-ocean ridge Molten materials erupts after moving out of the mantle Subduction at Deep-Ocean Trenches: subduction taking place Older and denser oceanic crust in the deep-ocean trenches Oceanic crust is new and hot Giant conveyor belt= mid-ocean ridge Subduction and Earth's Oceans: Atlantic ocean expanding Pacific ocean decreasing Why? Ridge not moving fast enoughin adding new crust