2.  Look in your notes for the definition of half-life. Write it down.  You have 12g of radioactive material. How much material will be radioactive after 2 half-lives?  How much time has gone by if each half life is 2 hours?

3.  The amount of time it takes for ½ of a radioactive sample to decay.  12g after 1 half-life = 6g  After 2 half lives = 3g  After 2 half-lives, 4 hours would have gone by.

4. WHOT 3/22  Dewium has a half-life of 5000 years.  When the sample was created it had 40g of radioactive material in it.  It now has 5g of radioactive material in it.  How long ago was this sample formed? Show all Work.

5.  The sample took 3 Half-lives to get from 40g to 5g.  Sample is 15,000 years old.

6. WHOT 3/23.  Mooglium has a half-life of 100 years.  When the sample was created it had 80g of radioactive material in it.  It now has 5g of radioactive material in it.  How long ago was this sample formed? Show all Work.

7.  Sample took 4 half-lives to get from 80g to 5g.  Sample is 400 years old.

8. 3/24 WHOT Put these events in order from oldest to youngest. Now suppose Layer D has been dated at 400,000 years old. A large earthquake caused the fault (F) Make a statement about when the earthquake happened? F D E C B A

10. EventYears ago(Yards)EraPeriod Last Mt. Rainier Eruption 192 First Known Fish 510,000,000 Less than 1 10Paleozoic Cenozoic Cambrian Quaternary

13. Geologic EventApproximate number of years ago Distance (yards) Geologic era Geologic period Most recent eruption of Mt. Rainier 192 yearsLess than 1 Cenozoicquaternary First known fish 510,000,000 years ago 10 ydPaleozoiccambrian Evidence of first life on Earth 3,800,000,000 years ago 76Archean Modern humans 200,000 years ago Less than 1 yd Cenozoicquaternary Formation of the Earth 4,600,000,000 years ago 92hadean

14. First known mammal 200,000,000 years ago 4Mesozoictriassic First single-celled organism 2,700,000,000 to 3,500,000,000 54-70 Galileo states the Earth revolves around the sun 397 years agoLess than 1 Cenozoicquaternary Oldest rock 4,400,000,000 years ago 88hadean Rise of the dinosaurs 230,000,000 years ago 5Mesozoictriassic

15. Extinction of the dinosaurs 65,000,000 years ago1Meso/cenoK/Tertiary First known plant 498,000,000 years ago10Paleozoicorcovician First known reptile 325,000,000 years ago7Paleozoicmissippian First multi-celled organism 700,000,000 years ago14proterozoic First known amphibian 375,000,000 years ago8MesozoicDevonian

16. First known bird 150,000,000 years ago3Mesozoic jurassic Renton is covered with glaciers a mile thick 10,000 years agoLess than 1Cenozoicquaternary Snowball Earth - entire planet covered with ice 650,000,000 years ago13proterozoic First flowers 130,000,000 years ago3Mesozoiccretaceous American Revolution ends 229 years agoLess than 1Cenozoicquaternary

18. Formation of continents

21. PresentEarths HistoryBeginning