1. Snowball Earth Roopa Kamesh Matt Beversdorf Kathy Groome

2. Theory of Snowball Earth
Continents and oceans were covered in ice approximately 600 million years ago.
Earth was in a deep freeze, chemical cycles were halted; carbon dioxide accumulated in the atmosphere causing an extreme greenhouse effect.
Believed to have caused the explosion of life forms seen in Cambrian fossils

3. Snowball Earth occurred during the Neoproterozoic

4. Existing Evidence Paleomagnetic Studies Banded Iron Formations
Glacial Deposits and Carbonate Caps
Paleomagnetic Studies
Banded Iron Formations
Manganese Deposits
Isotope Analysis
Plate Tectonics, Carbon Dioxide Emissions
Ice Albedo Feedback
Proterozoic Biostratigraphy: Persistence and
the Explosion of Life
Extremophiles

5. Glacial Deposits and Carbonate Caps

6. Paleomagnetic Studies
From Understanding Earth, Press and Seiver, W.H. Freeman and Co.

7. Banded Iron Formations

8. Carbon isotopes (Stanley, Steven, M., 1999)
Isotope Analysis
Carbon isotopes (Stanley, Steven, M., 1999)

9. Isotope Examples
Source: A.H. Knoll Learning to tell Neoproterozoic Time

10. Albedo Effect
Once the continents were glaciated to 30 degrees latitude, there was a runaway albedo effect.
Albedo refers to the reflective ability of a material. You can see the difference in how each material reflects sunlight in the table above.

11. Extremophiles
Extremophiles provide evidence that life could have persisted under snowball Earth conditions.

12. Problems with the Snowball Earth Theory

13. The Explosion of Life: Just a Coincidence?

14. Arguments Against
Organisms need sunlight and/or oxygen to survive (e.g. algae)
Freeze thaw structures – no glacial deposits on a completely frozen planet
Sea-level change – evidence for lowering of sea level
Inconsistency of isotope results: Kennedy
Carbon dioxide emissions - what about methane?

15. Alternative Theories Earth’s Obliquity: Increased Axial Tilt
Slushball Earth: A variation of snowball earth where the planet did not entirely freeze. This theory is based more on climate models for the Neoproterozoic.

16. What do you think???