GWBN+1.4


 * Section 1.4**

Vocabulary

 * mid-ocean ridge**- the largest chain of mountains in the world


 * sonar**- a device that bounces sound waves off under water objects and then records the echoes o these sound waves


 * sea-floor spreading**- the process that continually adds new material to the ocean floor


 * deep-ocean trenches**- deep under water canyons


 * subduction**- the process by which the ocean trench and back into the mantle

Outline
T= Sea Floor Spreading

-East Pacific Rise strange creatures -provided evidence for theory of continental drift
 * Summary**

-longest chain of mountains -curve into ocean, most mountains under water -mapped it by using sonar
 * Mapping the Mid-Ocean Ridge**

-ocean floor moves like conveyor belt carrying continents with them -At mid-ocean ridge molten material rises from mantle/erupts -spreads out pushing older material to both sides of ridge -Hess called continually add new material to ocean floor sea-floor spreading -evidence from molten material -four kilometers in ocean floor pillow shaped rocks -only forms when molten material hardens after erupting under water -evidence from magnetic stripes -Earth's magnetic poles reversed themselves 780,000 years ago -rocks in ocean floor lies in pattern of magnetized stripes
 * Evidence for Sea-Floor Spreading**