The Structure of the Earth
The Earth's Crust is broken into hugs slabs of rock called tectonic plates. There are seven major plates and several smaller ones. Tectonic plates 'float' on the denser mantle rock beneath. There are two types of tectonic plate. Oceanic plates are 5km to 10km thick, continental plates are 25km to 90km thick. Oceanic plates are made from denser rock than continental plates.
The map above shows the global distribution of the main tectonic plates. Notice how the world's major earthquake zones and volcanoes are found at the boundaries between different plates.
Pangaea - 200 million years ago, all the continents were joined together, forming a mega-island called Pangea.
The diagram above shows the red convection currents of the mantle which move the crust above it. The tectonic plates move about 5cm a year as the currents from the mantle below drag the tectonic plates along with them. The heat from the core causes very slow movements in…