1.1 OutlineEarth has several layers

I. Earth is made up of materials with different densities

1) Four main layers: inner core, outer core, mantle, crust

II. Earth’s layers have different properties

1) Scientists study how the energy from earthquakes and underground explosions travels

A. Core, Mantle, Crust1)1) Inner core:Inner core: a ball of hot, solid a ball of hot, solid

materials, enormous pressure; materials, enormous pressure; remains a solidremains a solid

2)2) Outer core:Outer core: layer of liquid metals that layer of liquid metals that surrounds inner core; remains a liquid surrounds inner core; remains a liquid due to lower pressuredue to lower pressure

3)3) Mantle:Mantle: thickest layer (2900 km or thickest layer (2900 km or 1700 mi); hot rock that is less dense 1700 mi); hot rock that is less dense than core; top part is cool & rigid; than core; top part is cool & rigid; below that is hot, thick pastebelow that is hot, thick paste

A. Core, Mantle, Crust4) Crust: thin layer of cool rock; 2 types:

continental (thickest), & oceanic (thinnest)

5) Lithosphere: made up of Earth’s crust & very top of mantle; most rigid of all layers

6) Asthenosphere: layer of hotter, softer rock in upper mantle; flows slowly like hot tar

III. Lithosphere is made up of many plates

1) Tectonic plates: large and small slabs of rock created from the lithosphere

2) Lithosphere can be compared to the cracked shell of a hard boiled egg

3) Most tectonic plates are made up of BOTH continental and oceanic crust

4) Two of the most important discoveries in geology are Earth’s layers and tectonic plates