Layers of the Earth Quick Facts • The earth is mostly made up of rock • 75% of the earth’s surface is covered by a thin layer of water. • Some of this water is frozen in the form of glaciers, ice, or snow • The entire planet is surrounded by a thin layer of gas called the atmosphere Crust • Thinnest of all the layers • Land: continental crust, 8-70km thick, granite • Ocean: oceanic crust, 8km thick, basalt • Solid • 22℃ Upper Mantle • 670 km below the Earth’s surface • 1,400-3,000 ℃ • The lower part of the upper mantle is both solid and liquid (melted) rock. • Iron, oxygen, silicon, magnesium, aluminum • The rock in the upper region is stiffer due to colder temperatures • Two distinct regions: Lithosphere and Asthenosphere Lithosphere • Includes the crust and the upper portion of the mantle • Coolest and most rigid • All tectonic activity occurs here • Tectonic plates • The movement of tectonic plates causes volcanoes, earthquakes, mountain formation • Mountains form from continental crust hitting continental crust or oceanic crust Asthenosphere • A denser, weaker layer beneath the lithosphere • 110-410km below earth’s surface • 300-500 ℃ • Rock is partially melted: semimolten • The lava that erupts in volcanoes comes from here Lower Mantle • 3,000 ℃ • 670-2,890 km below the surface • Solid rock: iron, oxygen, silicon, magnesium, and aluminum • Hot enough to melt, but is solid due to the pressure pushing down on it Outer core • Liquid layer of the core that is composed of iron, nickel, sulphur, and oxygen • 5,150km deep • Flows around the center of the earth • The movement of the metals creates our’ planets magnetic field • 4,000-6,000℃ Inner core • A huge metal ball • 2,500 km wide • Made mainly of iron with traces of nickel • 5,000-6,000 ℃ • Up to 6,000 times hotter than our atmosphere and hot enough to melt metal! • The metal stays solid due to the pressure surrounding it Resources • https://www.natgeokids.com/uk/discover/geography/physicalgeography/structure-of-the-earth/ • https://www.nationalgeographic.org/encyclopedia/mantle/
