EPS 201L - SNOWBALL EARTH

EPS 201L - SNOWBALL EARTH - EPS 201L Snowball Earth...

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EPS 201L Snowball Earth Questions 1. According to the authors, when and how many times did “snowball” conditions affect the Earth? 2. What was the first line of evidence (determined in the 1960s) that suggested Neoproterozoic global glacial conditions? 3. What unusual rock types are mixed in with some of the Neoproterozoic glacial deposits? 4. How did Joe Kirschvink explain the occurrence of iron-rich rocks mixed in the Neoproterozoic glacial deposits? 5. What rock type immediately overlies the Neoproterozoic glacial deposits? 6. What geologic tool did W. B. Harland use to determine the approximate position of Neoproterozoic continents? paleomagnetism 7. What did Harland conclude about the positions of the continents using this method? 8. What did Harland point in the early 1960s about the distribution of Neoproterozoic glacial deposits? According to the authors “snowball” conditions affected the earth four times between 750-580 millions of years ago. The first line of evidence to suggest Neoproterozoic global glacial conditions are glacial deposits near the equator between the tropics. Iron-rich rock is mixed in with some of the Neoproterozoic glacial deposits. This is unusual because we are accustomed to oxygen having an almost universal effect on the presence iron. Joe Kirschvink explains that millions of years of thick ice cover over the oceans would eventually lead to an elimination of oceanic oxygen. The lack of oxygen in the ocean to oxidize iron would have permitted the formations of such rocks as they appeared out of volcanic protuberances. Carbonate deposits rich in calcium and magnesium immediately overlies the
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EPS 201L - SNOWBALL EARTH - EPS 201L Snowball Earth...

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