Earth Structure Notes Composition What it is made

Earth Structure Notes

Composition (What it is made of) • Crust • Mantle • Core

The Crust • Outer layer • 5 - 100 km thick (3 – 60 miles thick) • Made of oxygen & silicon • 2 types of crust – Oceanic (very dense, made of basalt) – Continental (less dense, made of granite)

Oceanic and Continental Crust § Oceanic crust 3 – 5 miles thick § Continental crust on average 18 miles thick

The Mantle • Middle layer • Very thick layer • Made of iron & magnesium • 2, 900 km thick • Solid near core • Upper part is semi-solid

The Core • • Made mostly of iron & some nickel 1/3 of the earth’s mass Very hot 3, 428 km thick

Earth’s Layers • How are the earth’s layers similar to an egg? • Shell=crust • Egg white=mantle • Yolk=core

Physical Structure of the Earth (5 Layers) • • • Lithosphere Asthenosphere Mesosphere Outer Core Inner Core (LAMOI)

The Lithosphere • Rigid outer layer (crust + top part of mantle) • Made of oxygen & silicon • Made of moving tectonic plates • 60 – 300 km thick

Tectonic Plates • Earth’s lithosphere is broken into about 19 pieces • These plates move on top of the asthenosphere

The Asthenosphere • Semi-solid; solid but flows like liquid, called PLASTICITY • Part of Mantle • Plates float on this layer; moved by convection currents • 250 km thick

The Mesosphere • • Middle layer of Earth Very strong solid layer Lower part of mantle 2, 550 km thick

The Outer Core • • Liquid layer 4, 000 – 5, 000 Celsius Made up of nickel & iron 2, 200 km thick

The Inner Core • • • Solid, very dense 6, 000 Celsius Made up of iron 1, 228 km thick Extreme pressure makes it solid even though it is still very hot