3 Written questions
3 Multiple choice questions
- the process by which the ocean floor sinks beneath a deep-ocean trench and back into the mantle
- a device that bounces sound waves off underwater objects and then records the echoes of these sound waves.
- In a process taking tens of millions of years, part of the ocean floor sinks back into the mantle at deep-ocean trenches.
2 True/False questions
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.
deep-ocean trenches → deep underwater canyons