WHAT HAPPENS TO EARTH'S DISAPPEARING CRUST?

Scientists may have finally figured out the mystery of subduction zones

- Yasemin Saplakoglu

Like a giant broken-up cookie whose pieces float atop a sea of scalding milk, Earth’s outer shell is made of rocky rafts that constantly bump into and dive beneath each other in a process called plate tectonics. So what happens to those hunks of disappearing crust as they dive into Earth’s interior? It turns out that they get weak and bendy, like a slinky toy, but new modelling shows that they don’t disintegrate completely. The models also suggest that plate tectonics, at least in their modern form, likely only got going in the past billion years.