- The earth has an iron core surrounded by a mantle with a thin rocky crust on the outside
- The crust and the upper mantle are called the lithospheres, this is divided into tectonic plates
- These rigid plates move on the mantle because of convection currents
- Continental and oceanic plates
- Oceanic plates are denser than continental
- Silica rich magma is viscous and associated with explosive volcanoes.
- Iron magma is less dangerous
- Plate tectonics accepted because of evidence from shape; geology and fossils.