The Evolution of the Atmosphere: 4.6 to 1 billion years ago

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The Evolution of the Atmosphere4.6 to 1 billion
years ago

• By
• Ms. Holl

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Introduction

• THREE PARTS
• PART I Volcanoes
• PART II Single-Celled Plants
• Part III Multi-Celled Plants

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4.6 billion years ago
Formation of Earth
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4.5 billion years ago
Accretion of Earth
Formation of the Moon
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Part I

• Volcanoes

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4.2 billion years ago
Early Atmosphere
No Life! Volcanoes add carbon dioxide, ammonia,
water vapor and methane to the atmosphere.
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It was very HOT!
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3.8 billion years ago
Earth Cools to Below 100 deg. C
Liquid Water Present Early Oceans Form
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Part II

• Multi-Celled Plants

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3.8 billion years ago
Earth Cools to Below 100 deg. C
First Bacteria (Prokaryotic)
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3.5 billion years ago
Photosynthesis Produces Oxygen!
Stromatolites
Carbon is locked up in sedimentary rocks.
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Stromatolites
Formed by colonies cyanobacteria. At least 3.5
billion years old. Carbon is stored in
stromatolites. Fact Chloroplasts are actually
cyanobacteria living in plant cells!
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0.5 to 3.5 billion years ago
Stromatolites, colonies of cyanobacteria, are
alive in Australia today.
Shark Bay, Australia
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2.1 billion years ago
Photosynthesis Produces Oxygen!
Oxygen Ammonia
NITROGEN!
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2-3 billion years ago Little free oxygen
Commonly occur in sedimentary rocks 2-3 billion
years old. Alternating dark bands (containing
FeO) and light bands of chert (silica and Fe2O3).
Occur from the deposition of alternately
dissolved FeO chert. Bands occur from
fluctuating densities of bacteria in an ocean.
When bacteria blossoms, it creates oxygen and
thus chert, which falls to the ocean floor. An
oxygen depletion allows for FeO.
Banded iron formation
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2 billion years ago
Beginning of Oxygenated Atmosphere
First Pollution Crisis!
Redbeds
Evidence of significant free oxygen
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History of Atmospheric Oxygen
The presence of FeS2 and UO2 set upper limits
because oxygen would have produced other oxides
from U and Fe
From Lunine 1999 based on Kastings (1991)
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Red beds
Occur earlier than 2 billion years ago. Form
when iron is weathered out of rock in the
presence of oxygen.
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1.7 billion years ago
Single-celled Eukaryotes Appear
Cells get a nucleus!
Still Present
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Part III

• Multi-Celled Plants

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1.2 billion years ago
Multi-celled Plants Appear
Photosynthesis adds more ___???___. Decaying
plants add more NITROGEN.
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1.2 billion years ago
Multi-celled Plants Appear
Photosynthesis adds more OXYGEN. Decaying plants
add more NITROGEN.
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0.65 billion years ago to NOW
Humans did not appear until 5 million years ago!
Still Present
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Summary

• PART I Volcanoes add carbon dioxide, ammonia,
  methane, and water vapour to the atmosphere.
• PART II Single-celled plants begin to
  photosynthesize which decreases the amount of
  carbon dioxide and increases the amount of oxygen
  in the atmosphere. The oxygen reacts with ammonia
  from volcanoes to add nitrogen to the atmosphere.
  
• PART III Multi-celled plants evolved which adds
  even more oxygen to the atmosphere. More nitrogen
  is added as plants decay and are consumed by
  denitrifying bacteria.

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Review Questions

• Millions of years ago, the atmosphere contained
  the following gases
• Ammonia, carbon dioxide, methane, nitrogen,
  oxygen and water vapor.
• Which of these gases has increased?
• Which of these gases has decreased?

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Review Questions

• Does photosynthesis increase or decrease the
  amount of oxygen in the atmosphere?
• WHY?
• Does photosynthesis increase or decrease the
  amount of carbon dioxide in the atmosphere?
• WHY?

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Review Questions

• How did volcanoes change the atmosphere?
• How did single-celled plants change the
  atmosphere?
• How do multi-celled plants change the atmosphere?

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To think about

• How is the composition of the atmosphere changing
  today?

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Picture Sources
http//rainbow.ldeo.columbia.edu/courses/v1001/7.h
tml http//www.geol.umd.edu/kaufman/ppt/chapter3/
sld019.htm http//www.uta.edu/geology/geol1425eart
h_system/images/gaia_chapter_11/ArcheanLandscape.j
pg http//www.uta.edu/geology/geol1425earth_system
/1425chap11.html http//www.geol.umd.edu/kaufman/
ppt/chapter3/sld019.htm http//www.exhibits.lsa.um
ich.edu/Exhibits/Anthropology/Diaramas/Nat.Am./Cop
per/Copper.html http//www.novaspace.com/LTD/TUCC/
PIX/Atmo.jpeg http//www2.jpl.nasa.gov/files/image
s/browse/p46022bc.gif http//www.gsfc.nasa.gov/gsf
c/earth/pictures/pinatubo/atmosphere20after.jpg h
ttp//commons.wikimedia.org/wiki/ImageAir_composi
tion_pie_chart.JPG http//www.photolib.noaa.gov/sa
nctuary/images/big/sanc0001.jpg
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Information Sources

• http//www.udayton.edu/INSS/ThemeEvol/EvolTimelin
  e.HSM.ppt
• http//www.lpl.arizona.edu/undergrad/classes/sprin
  g2006/Griffith_102-13/LectureNotes/L36-Evolution-L
  ife.ppt
• http//thurmanscience.tripod.com
• http//www.olduniverse.com/1,2.htm