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Geologic History of the Earth

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Evolution of large plants, trees, flowers, grasses (600 MYA) Creation of Ozone (O3) ... Does the geologic history of the Earth lead to the formation of life? ... – PowerPoint PPT presentation

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Title: Geologic History of the Earth


1
Geologic History of the Earth
2
Star Formation begins with a nudge
3
Formation of the Solar System
4
(No Transcript)
5
Planetary accretion
6
Why terrestrials and Jovians?
7
(No Transcript)
8
Terrestrial Composition
9
Jovian Composition
10
Leftover Debris
11
Kuiper Belt
12
Oort Cometary Cloud
13
Formation of the Moon (4.5 BYA)
14
Structure of the Earths Interior
15
(No Transcript)
16
Early Bombardments
  • Heaviest impacts lasted 100 million years
  • Tapered off 3.5 billion years ago
  • Evidence?
  • Impacts still occur today

17
Cratered Worlds
18
(No Transcript)
19
Formation of the Oceans and Atmosphere
  • Earth was not formed with atmosphere
  • Gasses brought by planetesimals
  • Outgassing and impacts released gasses
  • H20 CO2 N2 H2S SO2
  • Water vapor condensed to form oceans
  • Oceans were in place 4.3 4.4 BYA

20
Earths Primitive Atmosphere
  • Produced by outgassing
  • Formed 4.3 4.4 billion years ago?
  • Rich in hydrogen, carbon, nitrogen, oxygen
  • CO CO2 N2 H2O some H H2
  • Contained complex molecules from ISM
  • Hydrogen lingered for a few million years

21
Atmospheric Retention
photodissociation
  • Molecular velocity

Planetary Escape Velocity
22
Evolution of the Earths Atmosphere
  • Oxygen Levels Currently 21
  • 2-2.3 billion years ago
  • Photosynthesis
  • Originally oxidation kept pace with oxygen
    production (CO ? CO2, rust)
  • Evolution of large plants, trees, flowers,
    grasses (600 MYA)

23
Creation of Ozone (O3)
  • O2 UV ? O O
  • O O2 ? O3
  • Requires the absence of hydrogen
  • Significantly increased 600 MYA
  • Ozone allowed life to venture onto land

24
Evolution of the Earths Atmosphere
  • Nitrogen Levels Currently 78
  • Liberated by outgassing
  • Significance of denitrifying bacteria
  • Atmospheric nitric oxide (NO) ? rain ?
    soil/oceans ? bacteria ? atmosphere

25
Evolution of the Earths Atmosphere
  • Argon Currently 1
  • Inert formed by radioactive decay of potassium
  • Liberated by outgassing

26
Evolution of the Earths Atmosphere
  • Carbon dioxide Currently 0.01
  • Dominated early atmosphere
  • locked up in calcium carbonates (limestone,
    chalks)

27
  • Carbon cycle
  • Accelerated by living sea creatures

28
  • Does the geologic history of the Earth lead to
    the formation of life?
  • Does this make life unique to the Earth?
  • Atmosphere has been altered by life
  • Existence of extrasolar planets has been
    confirmed

29
  • Chapter 11 260 278 (Q 1, 2, 3)
  • Chapter 8 189 196 (Q 2, 3, 4)
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