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Early Evolution

Geologic Time Part 3

TermDefinition
4.6 Billion Years Ago Radioactive decay shows that Earth formed
4.5 Billion Years Ago During the formation Earth heated up due to radioactive decay of isotopes within the Earth's interior
4.4 Billion Years Ago During early Earth's melting, material separated into zones according to their densities, Fe and Ni settled into the core, silicates formed the earliest crust, gaseous compounds made up the atmosphere
4.2 Billion Years Ago Solid crust formed and plate tectonics started, gases trapped inside the Earth seeped out in a process called outgassing and created a completely different second atmosphere
3.9 Billion Years Ago After the crust had cooled enough, water vapor in the atmosphere began to precipitate and form water on Earth
3.8 Billion Years Ago Weathering, erosion, and deposition began and the first sedimentary rock was formed
3.5 Billion Years Ago Life forms that used CO2 and released free oxygen began to evolve, this allowed for oxygen to start collecting in our atmosphere
3.5-2.8 Billion Years Ago Oxygen in the atmosphere reacted with iron in the soil t o produce rust, resembled the surface color of current day Mars
2.8 Billion Years Ago Most of the iron compounds that could have reacted with the oxygen had done so, thus oxygen in the atmosphere increased
2.8 - Present Billion Years Ago Life slowly evolved from single-celled bacteria to multicellular to hard parts on life forms
Created by: cmbinder197
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