Book 12, Question 73
Why Does the Seafloor Get Recycled But the Continents Don’t?
The seafloor gets recycled, but the continents mostly stay! Heavy seafloor sinks back into the mantle. Lighter continents float too high to sink, like a cork in a bowl of water.
More fun facts
- Ocean plates are heavy, so they can sink into the mantle.
- Continental plates are made of lighter minerals.
- Continental crust floats like a cork on denser rock beneath it.
- Because it is thicker and lighter, most continental crust does not sink deep enough to be recycled.
- Today's continents are much older than today's seafloor.
Sources: U.S. Geological Survey, U.S. Geological Survey
Questions kids ask
Why is the seafloor young?
Old seafloor keeps sinking back into Earth, while continents stay on top.