12: Scratching the Surface

How is new crust made, and why isn't the Earth constantly expanding like a party balloon? To answer these questions, we'll track the life, death, and rebirth of Earth's surface. Stops along the way include the Mid-Atlantic Ridge, a fight to the death beneath New Zealand, and a stop for some Italian dessert.

Extra credit: Experiment with your carpets at home, pushing them together and testing which one sinks beneath the other.