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Early Evolution
Geologic Time Part 3
| Term | Definition |
|---|---|
| 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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