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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? - PowerPoint PPT Presentation
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Warm Up, October 2nd, 20131) 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%?
2) What has NOT happened to over 99% of life on Earth?
3) What 3 criteria make up a good Index Fossil?
4) 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
5 + 5 Absolute
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 singlecelled 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)
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