Geography Earth Forces Take a new page in your jotter and design a title page called “Earth Forces” 1

Structure of the Earth [Date] Today I will: Geography Earth Forces Structure of the Earth [Date] Today I will: Know that the Earth is made up of four parts and be able to describe each area. 2

Geography Earth Forces 3

Geography Earth Forces The Earth is almost a sphere, but more like a tangerine! It is squashed at the top and the bottom. 4

Geography Earth Forces 5

Geography Earth Forces The Earth is composed of four different layers. Many geologists believe that as the Earth cooled the heavier, denser materials sank to the centre and the lighter materials rose to the top. The crust is made of the lightest materials (rock- basalts and granites) and the core consists of heavy metals (nickel and iron). 6

Geography Earth Forces The Earth's Crust is like the skin of an apple. It is very thin in comparison to the other three layers. The crust is only about 3-5 miles (8 kilometres) thick under the oceans (oceanic crust) and about 25 miles (32 kilometres) thick under the continents (continental crust). 7

Geography Earth Forces The crust is broken into huge pieces called tectonic plates. These are moving constantly at a few centimetres per year. 8

Geography Earth Forces The mantle is composed of very hot, dense rock. This layer of rock flows slowly due to great temperature differences from the bottom to the top of the mantle. 9

Geography Earth Forces At the centre of the Earth lies the core, which is nearly twice as dense as the mantle because its composition is metallic (iron-nickel) rather than stony. The Earth's core is actually made up of two distinct parts: a 2,200 km-thick liquid outer core and a 1,250 km-thick solid inner core. 10