Goals To understand: (1) solar nebula theory for formation of Earth, (2) how this led to Earth’s stratification, and (3) methods used to understand Earth’s layering.
Early Earth Hadean Eon and stratification
Early Earth About 4,000-million years ago semi-permanent crust formed
Earth’s layers • Core • Solid inner core • Liquid outer core • Mantle • The upper and lower mantle • The asthenosphere Relative thickness of layers
Earth’s layers The lithosphere • Rigid upper-most mantle • The crust: thin rind of light elements floating on top of Earth.
1. Composition of meteorites Iron-nickel alloy Magnesium-silicate rocks
2. Inclusions of mantle in volcanic rocks The mantle
3. Fragments of uppermost mantle trapped in mountain belts The mantle in Oman
4. Behavior of sound waves from earthquakes & large explosions Structure of fetus modeled from sound velocities Structure of mantle modeled from sound velocities