Earth has several layers 1.1 Outline Earth has several layers

I. Earth is made up of materials with different densities Four main layers: inner core, outer core, mantle, crust

II. Earth’s layers have different properties Scientists study how the energy from earthquakes and underground explosions travels

A. Core, Mantle, Crust Inner core: a ball of hot, solid materials, enormous pressure; remains a solid Outer core: layer of liquid metals that surrounds inner core; remains a liquid due to lower pressure Mantle: thickest layer (2900 km or 1700 mi); hot rock that is less dense than core; top part is cool & rigid; below that is hot, thick paste

A. Core, Mantle, Crust Crust: thin layer of cool rock; 2 types: continental (thickest), & oceanic (thinnest) Lithosphere: made up of Earth’s crust & very top of mantle; most rigid of all layers Asthenosphere: layer of hotter, softer rock in upper mantle; flows slowly like hot tar

III. Lithosphere is made up of many plates Tectonic plates: large and small slabs of rock created from the lithosphere Lithosphere can be compared to the cracked shell of a hard boiled egg Most tectonic plates are made up of BOTH continental and oceanic crust Two of the most important discoveries in geology are Earth’s layers and tectonic plates