Layers of Earth Crust • Description: Outer Most Layer. All life on Earth exists within few hundred meters • Thickness: 5- 60 km Crust • Composition: All 92 natural elements • Temperature: 20600 Celsius • Density: 2.7 g/cm3 Mantle • Description: 80% Earth volume 68% mass. High temperature and pressure makes mantle a thick flowing liquid • Thickness: 2800 km Mantle • Composition: Silicon, Oxygen, Iron, magnesium • Temperature: 1003000 Celsius • Density: 3.0 g/cm3 Outer Core • Description: Surrounds inner core. Tremendous heat makes the outer core molten or a hot liquid • Thickness ~2150 Km Outer Core • Composition: Liquid Iron and Nickel • Temperature ~ 3000-6500 OC • Density ~ 12 g/cm3 Inner Core • Description: Solid innermost layer of Earth. Very dense, enormous pressure keeps it solid. • Thickness ~ 1230 Km (radius) Inner Core • Composition: Solid Iron and Nickel • Temperature ~7000 OC • Density ~ 12 g/cm3 Birth of a Theory Video • What led Wegener to his idea of continental drift and what was the driving force behind the movement of continents? • What is, and where does sea floor spreading occur? • How did paleomagnetism help support the notion of sea floor spreading? • How do transform faults help support the theory of sea floor spreading? • Plate tectonics is characterized as a model that describes everything, Explain.