1 / 30

Topic 4

Topic 4. The Evolution of the Atmosphere. Lesson 1. The Atmosphere. The Atmosphere. Most of life on Earth today has evolved to survive in an oxygen rich environment. If these organisms of today were exposed to the Earth’s original atmosphere they would die very quickly. .

sofia
Download Presentation

Topic 4

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Topic 4 The Evolution of the Atmosphere

  2. Lesson 1 The Atmosphere

  3. The Atmosphere Most of life on Earth today has evolved to survive in an oxygen rich environment. If these organisms of today were exposed to the Earth’s original atmosphere they would die very quickly.

  4. Earth’s Original Atmosphere The source of gases that formed Earth’s original atmosphere came from within the Earth. Molten rocks and material released gases trapped within the Earth. Volcanoes still do this today.

  5. Earth’s Early Atmosphere The relative proportion of gases are uncertain but scientists have determined the following gases to have made up the Earth’s early atmosphere: • Nitrogen N2 • Carbon Monoxide CO • Carbon Dioxide CO2 • Methane CH4 • Water vapour H2O

  6. Earth’s Current Atmosphere Scientists are able to perform first hand investigations to measure the gases of the atmosphere today.

  7. Where did the original atmosphere go? Nitrogen: Most of this gas remains in the atmosphere because it is un-reactive.

  8. Where did the original atmosphere go? Carbon Monoxide and Carbon Dioxide: The early atmosphere contained 100 to 1000 times as much carbon dioxide as it does today. These gases combined with calcium and magnesium dissolved in the oceans and formed carbonate sediments. This process is called precipitation. (Limewater Lab)

  9. Where did the original atmosphere go? Hydrogen: Because hydrogen is so light, Earth’s gravitational field was not enough to hold this gas in the atmosphere. Most was lost into space.

  10. Where did the original atmosphere go? Water Vapour: As the Earth cooled, water vapour in the atmosphere condensed and fell as rain.

  11. Where did the original atmosphere go? Methane: Methane would have reacted with Oxygen which produces Carbon Dioxide and Water.

  12. Where did the current atmosphere come from? Nitrogen: This gas remains from the original atmosphere. Oxygen: Produced as ‘waste’ during photosynthesis.

  13. Where did the current atmosphere come from? Argon: Formed by the radioactive decay of elements within the mantle and is released as volcanic gas.

  14. Where did the current atmosphere come from? Carbon Dioxide: CO2 is added to the atmosphere by volcanic eruptions, weathering of carbonate rocks, respiration of living things and in recent times by burning fossil fuels.

  15. Where did the current atmosphere come from? Water Vapour: The water cycle continually recycles water vapour in the atmosphere.

  16. Homework • Write up Precipitation of Carbonate Minerals Activity 1.17 (pg 28) Prelim Spotlight Text in your lab books.

  17. Lesson 2 Precipitation of Carbonate Minerals Prac

  18. Homework Complete DOT Point 4.3 pg 22

  19. Lesson 3 Early Life Forms-Photosynthesis

  20. Stromatolites These are layered structures, believed to have been created from ancient bacteria.

  21. Stromatolites These ancient structures provide evidence for early life and have been found in Western Australia. They have been dated at 3.45 billion years old!!!

  22. Stromatolites • These ancient organisms dominated the fossil record between 1 and 2 BYA. They are found in many different shapes and sizes but all have an alternating layers of lime and silt.

  23. Stromatolites Today stromatolites are still forming and can be found at Shark Bay, Western Australia.

  24. Formation of Present Day Stromatolites Scientists have studies these present day stromatolites to learn what they may have been like 1-2 BYA. Scientists have discovered that they are formed by the actions of cyanobacteria.

  25. Formation of Present Day Stromatolites Cyanobacteria are prokaryotic (no nucleus) and are photosynthetic (use sunlight to make food and produce oxygen as a by-product). Why does this matter? BECAUSE THESE ORGANISMS PRODUCE OXYGEN!!! Something our early atmosphere did not have!!

  26. Formation of Present Day Stromatolites These simple bacteria photosynthesise and produce oxygen. See the equation for Photosynthesis below: Is this process different from respiration?

  27. Formation of Present Day Stromatolites • Yes it is, but how? Photosynthesis: Respiration:

  28. Formation of Present Day Stromatolites If ancient stromatolites were formed in the same way present day stromatolites are formed, what would be the implications regarding the free oxygen in the atmosphere?

  29. Formation of Present Day Stromatolites This has caused great debate….. And because there is no direct evidence about the ancient bacteria (they are not fossilised in the rocks) scientists are unable to conclude the exact processes they underwent.

  30. Homework • Read pages 30-31 Prelim Spotlight Text • Update vocab list • Complete DOT Point 4.1-4.2 pg 21

More Related