Continental drift theory
Step-by-step explanation:
Movement of plates in the lithosphere (plate tectonics) caused the hypothesis of continental drift to become a theory
- Alfred Wegener first presented the hypothesis that the continents had once formed a single landmass, called Pangaea, before breaking apart and drifting to their present locations
- Wegener thought all the continents were once joined together before breaking up and drifting to their current positions
- Most of Wegener's observations about fossils and rocks were correct but he was wrong on a couple of key points
- Plate tectonics is now the widely accepted theory that Earth's crust is fractured into rigid, moving plates
- In the 1960's, scientists discovered the plate edges through magnetic surveys of the ocean floor and through the seismic listening networks built to monitor nuclear testing
- Plate tectonics is the theory that Earth's outer shell is divided into several plates that glide over the mantle, the rocky inner layer above the core
- The plates act like a hard and rigid shell compared to Earth's mantle and this strong outer layer is called the lithosphere
- The lithosphere includes the crust and outer part of the mantle