Earth Science 7 The Layers of the Earth
Layers of the Earth The Earth is composed of four different layers The crust The mantle The outer core The inner core
The Crust The crust is the solid surface on the outside of the planet It ranges from 5 to 50 km thick The crust has temperature ranging from 5°C Near the surface to 1000°C at its base
The Crust The crust is less dense than the deeper layers of the Earth. This allows the crust to float on top of the Mantle The boundary between the crust and mantle is the Moho (Mohorivicic Discontinuity)
The Mantle The Mantle is partly melted layer the layer below the crust The mantle is ~2900 km thick and ranges from 1000ºC to 2500 ºC
The Mantle The upper mantle flows like chewy caramel The deeper you go the denser the mantle gets because of the pressure of the layers above The lower mantle doesn’t flow
The Core The core is divided into two layer: The outer core The inner core
The Outer Core The outer core is ~2200 km thick The temperature increases from 4000°C to 5500°C It is an extremely dense liquid layer composed mostly of iron and nickel The outer core’s outer layer flows
The Inner Core The inner core is the middle of the Earth It is almost as hot as the surface of the sun, but kept solid by the pressure It is 1250 km thick It has a temperature of 6000ºC
Earthquake Evidence for Earth’s Structure One piece of evidence for the structure of the Earth is the movement of P waves. The time that seismic waves arrive at distant points doesn’t work for a uniform Earth
Review of the Earth’s Layers The Earth has four layers: The crust The mantle The outer core The inner core Each layer has a different temperature, thickness, and composition