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Wednesday November 9, 2011

Wednesday November 9, 2011. (Origin of the Atmosphere and Oceans ). The Launch Pad Wednesday, 11/9/11. Briefly describe the following components of Earth’s structure:. crust upper mantle lower mantle outer core inner core. Brittle, oceanic & continental, thin.

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Wednesday November 9, 2011

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  1. WednesdayNovember 9, 2011 (Origin of the Atmosphere and Oceans )

  2. The Launch Pad Wednesday, 11/9/11 Briefly describe the following components of Earth’s structure: crust upper mantle lower mantle outer core inner core Brittle, oceanic & continental, thin Solid but mobile, asthenosphere Solid, hot, dense rocky material Liquid, metallic, iron & nickel, creates magnetic field Solid metallic, iron & nickel, extremely high pressure

  3. Announcements I will be available today after school until 4:45 PM. We may have a Quiz tomorrow.

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  5. Over 4 billions years ago volcanic activity was producing Earth’s primitive atmosphere and oceans. Figure 12.6 Stromatolite bacteria mounds

  6. Earth’s primitive atmosphere, which consisted mainly of H2O vapor and CO2, was formed by a process called “outgassing”, in which gases trapped in the planet’s interior are released by volcanic eruptions. Figure 12.7 This process continues today.

  7. Origin of the Atmosphere and Oceans Water vapor condensed to form clouds and rainwater that formed the oceans.

  8. Origin of the Atmosphere and Oceans About 3.5 billion years ago, photosynthesizing bacteria began to release oxygen.

  9. Origin of the Atmosphere and Oceans Oxygen levels steadily increased

  10. Origin of the Atmosphere and Oceans Eventually oxygen levels were sufficient for ozone to develop in the atmosphere.

  11. These layered, iron-rich rocks, called banded iron formations, were deposited during the Precambrian. Much of the oxygen generated as a by-product of photosynthesis was readily consumed by chemical reaction with iron to produce these rocks.

  12. Origin of the Atmosphere and Oceans Outgassing produced acidic conditions that caused an accelerated rate of weathering of Earth’s rocky surface.

  13. Origin of the Atmosphere and Oceans Products of this weathering were carried to the oceans, thus increasing the salinity of the oceans..

  14. Origin of the Atmosphere and Oceans The oceans also served as a depository for carbon dioxide, which is readily soluble in water.

  15. CO2 reacts with other substances in seawater to form calcium carbonate (limestone.) Eventually, marine organisms would removed calcium carbonate from the seawater to make their shells. When these organisms died, their remains were deposited on the seabed in the form of chalk. These chalk beds later became exposed, as in this picture of the White Cliffs of Dover, in southern England.

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