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Warm Up, October 2 nd , 2013. 1) C-14 has gone through how many half-lives if it’s about 23,000 years old? What % is left if it starts at 80%? What has NOT happened to over 99% of life on Earth ? What 3 criteria make up a good Index Fossil?
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Warm Up, October 2nd, 2013 1) C-14 has gone through how many half-lives if it’s about 23,000 years old? What % is left if it starts at 80%? What has NOT happened to over 99% of life on Earth? What 3 criteria make up a good Index Fossil? What can ice cores tell us about Earth of the past? (2 examples)
Looking at a clock? Absolute Looking at sedimentary layers? Relative Looking at an index fossil? Relative Measuring C-14? Absolute Absolute 5 + 5
Geologic Time • The scale scientists use to determine the order of events and when they took place on Earth.
How do we measure Geologic Time? • In several sections: • Eons (biggest) • Eras • Periods • Epochs (smallest)
* • * Precambrian Eon Phanerozoic Eon • Most of Earth’s history • 4 Billion Years • No large life • (microscopic) • Very little of Earth’s history • 500 million years • Larger life begins • (non-microscopic) • * • *
Speaking of microscopic life… Is it possible to have fossils of single celled life? Why or why not?
Radioactive Decay • What do you associate these words with?
Half Life Worksheet - Partners • Complete Worksheet, show work • Will review in 15 minutes
Study Guide • Begin now, due Thursday • (Yeah, that’s tomorrow)