The Evolution of the Atmosphere: 4.6 billion years ago - present NOTES The Evolution of the Atmosphere: 4.6 billion years ago - present Mr. Chary

collision of smaller planets. NOTES 4.6 billion years ago Earth is formed by the collision of smaller planets.

NOTES 4.5 billion years ago Formation of the Moon

NOTES 4.2 billion years ago Early Atmosphere No Life! Volcanoes add carbon dioxide, ammonia, water vapor and methane to the atmosphere.

NOTES It was very HOT!

Earth Cools to Below 100 deg. C NOTES 3.8 billion years ago Earth Cools to Below 100 deg. C Liquid Water Present Early Oceans Form

NOTES First Bacteria (Prokaryotic)

Photosynthesis Produces Oxygen! NOTES 3.5 billion years ago Photosynthesis Produces Oxygen!

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!

Stromatolites, colonies of cyanobacteria, are alive in Australia today. Interesting fact to tie the past to the present Shark Bay, Australia

Photosynthesis Produces Oxygen! NOTES 2.1 billion years ago Photosynthesis Produces Oxygen! Oxygen + Ammonia = Nitrogen was also produced by decaying organisms NITROGEN!

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

Beginning of Oxygenated Atmosphere NOTES 2 billion years ago Beginning of Oxygenated Atmosphere

Evidence of significant free oxygen Red beds Occur earlier than 2 billion years ago. Form when iron is weathered out of rock in the presence of oxygen. Evidence of significant free oxygen

Single-celled Eukaryotes Appear NOTES 1.7 billion years ago Single-celled Eukaryotes Appear Cells get a nucleus!

Multi-celled Plants Appear NOTES 1.2 billion years ago Multi-celled Plants Appear Photosynthesis adds more ___???___.

Multi-celled Plants Appear NOTES 1.2 billion years ago Multi-celled Plants Appear Photosynthesis adds more OXYGEN.

Oxygen is at current levels. NOTES 600 million years ago - NOW Oxygen is at current levels. Still Present:

Compare the original composition of the atmosphere to the present day one. It is very different!

NOTES Summary Volcanoes add carbon dioxide, ammonia, methane, and water vapour to the atmosphere. 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. Multi-celled plants evolved which adds even more oxygen to the atmosphere.

Review Questions Millions of years ago, the atmosphere contained the following gases: Ammonia, carbon dioxide, methane, nitrogen, oxygen and water vapor. 1. Which of these gases has increased? 2. Which of these gases has decreased?

Review Questions 3. Does photosynthesis increase or decrease the amount of oxygen in the atmosphere? WHY? 4. Does photosynthesis increase or decrease the amount of carbon dioxide in the atmosphere?

Review Questions 5. How did volcanoes change the atmosphere? 6. How did single-celled plants change the atmosphere? 7. How do multi-celled plants change the atmosphere?

To think about… How is the composition of the atmosphere changing today?

Picture Sources http://rainbow.ldeo.columbia.edu/courses/v1001/7.html http://www.geol.umd.edu/~kaufman/ppt/chapter3/sld019.htm http://www.uta.edu/geology/geol1425earth_system/images/gaia_chapter_11/ArcheanLandscape.jpg http://www.uta.edu/geology/geol1425earth_system/1425chap11.html http://www.exhibits.lsa.umich.edu/Exhibits/Anthropology/Diaramas/Nat.Am./Copper/Copper.html http://www.novaspace.com/LTD/TUCC/PIX/Atmo.jpeg http://www2.jpl.nasa.gov/files/images/browse/p46022bc.gif http://www.gsfc.nasa.gov/gsfc/earth/pictures/pinatubo/atmosphere%20after.jpg http://commons.wikimedia.org/wiki/Image:Air_composition_pie_chart.JPG http://www.photolib.noaa.gov/sanctuary/images/big/sanc0001.jpg

Information Sources http://www.udayton.edu/~INSS/ThemeEvol/EvolTimeline.HSM.ppt http://www.lpl.arizona.edu/undergrad/classes/spring2006/Griffith_102-13/LectureNotes/L36-Evolution-Life.ppt http://thurmanscience.tripod.com http://www.olduniverse.com/1,2.htm