early earth
DESCRIPTION
Early Earth. …early bombardment…. …earliest phase of Earth heating…. …thin atmosphere of H, CO 2 , H 2 O, N 2 , CO, NH 3 , CH 4. …first seas…. Early Bombardment 2 phases?. Relative dating. Earth Developed a Magma Sea 4.5-4.0 billion years ago. - PowerPoint PPT PresentationTRANSCRIPT
Early Earth…earliest phase of Earth heating…
…first seas…
…thin atmosphere of H, CO2, H2O, N2, CO, NH3, CH4
…early bombardment…
Early Bombardment
2 phases?
Relative dating
Early Earth began to heat as the last extraterrestrial collisions subsided1. Rock is a good insulator – stores heat2. Collisions produced heat that was stored3. Radioactivity4. Gravitational contraction
Earth Developed a Magma Sea4.5-4.0 billion years ago
What is the physical consequence of melting a ball of rock with many different types of elements and compounds?
Temperature reached melting point of iron:
• Liquid iron flowed inward• Friction raised temperature
• Less dense compounds flowedoutward (SiO2 and others)
“Iron Catastrophe”
Planet became chemicallydifferentiated
Fe/Ni
Fe/Mg
IncreasingFe toward
core
IncreasingSi towardsurface
There are certain trends in Earths chemistry.The crust is relatively depleted in Fe, Mg and enriched in Si, O
Effect ofchemical differentiation
There are certain trends in Earths chemistry.The crust is relatively depleted in Fe, Mg and enriched in Si, O
Earth’s magnetic fieldemanates from the core complex and surrounds the planet.
Magnetism gained from early nebula ismagnified by turbulentiron, nickel fluid of outer core.
Magnetic field envelops entire planet
Polarity + - tends to reverse
and fluctuate with time
Earth is probably not built ofuniform layers, it is likely mixed
somewhat by convection
MANTLE PLUMES warm rock rises,
cool rock descends
How will the lithosphere
respond to a plume?
The continental
rifting process
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