CCKH+1.4

Vocabulary:

 * Mid-Ocean Ridge**: longest chain of mountains in the world
 * Sonar**: a device that bounces sound waves off under water objects and records the echos
 * Seafloor Spreading**: the process that continually adds new material to the ocean floor.
 * Deep-Ocean Trench**: forms where the oceanic crust bends downward
 * Subduction**: the process by which the ocean floor sinks beneath a deep ocean trench and back into the mantle.

Outline:

 * ===Sea-Floor Spreading===
 * East Pacific Rise
 * region of the Pacific Ocean
 * coasts of Mexico and South America
 * water heated by mantle material
 * ===Mapping the Mid-Ocean Ridge===
 * mid-ocean ridge
 * sonar
 * ===Evidence for Sea-Floor Spreading===
 * molten material rises from mantle
 * sea-floor spreading
 * Evidence from Molten Material
 * Alvin's submarine
 * found strange rocks
 * Evidence from Magnetic Stripes
 * direction of Earth's magnetic field
 * Evidence from Drilling Samples
 * the Glomar Challenger, drilling ship
 * ===Subduction at Deep-Ocean Trenches===
 * deep-ocean trenches
 * subduction
 * ===Subduction and Earth's Oceans===
 * subduction in the Pacific Ocean
 * pacific ocean covers more than 1/3 of the planet
 * subduction in the Atlantic Ocean
 * expanding ocean