Fill in the Blanks Activity about the layers of EarthOnline version Complete the sentences by Teresa Rey Granados 1 Four layers The is the top layer of the geosphere . It is thinner than the others layers . The is solid and forms the continents and ocean floor . The is the thickest layer of the geosphere . It is made up of magma , which is semi - liquid rock . The is the layer around the . The is liquid . The is the centre of the Earth . It is also the hottest part .