3 Written questions
3 Multiple choice questions
- a device that bounces sound waves off underwater objects and then records the echoes of these sound waves.
- deep underwater canyons
- an undersea mountain chain that is part of a long system of mountains that winds beneath Earth's oceans.
2 True/False questions
What happens at deep-ocean trenches? → In a process taking tens of millions of years, part of the ocean floor sinks back into the mantle at deep-ocean trenches.
What is the evidence for sea-floor spreading? → In sea-floor spreading, the sea floor spreads apart along both sides of a mid-ocean ridge as new crust is added. As a result, the ocean floors move like conveyor belts, carrying the continents along with them.