1. The Age of Things: Sticks, Stones and the Universe Correcting and Using Carbon 14 http://cfcp.uchicago.edu/~mmhedman/compton1.html

2. Last Time: Current Carbon-14 Fraction Original Carbon-14 Fraction R = Carbon-14 Fraction = Carbon 14 All Carbon R

3. A personal aside: R

4. This says the tree from which this sample was taken was fallen ~14000 yrs ago. However, (we) cannot judge this date as valid w/o adequate context: Does this date make sense in terms of other dates at the site? For a single date is not very reliable in these situations. Furthermore, is the sample contaminated? Could there be factors that would cause the date to be erroneous? Also the date has not been properly altered to take into account fluctuations in radiocarbon levels from year to year. Finally, even if the above factors were taken into account, we only know when the tree was cut down (when it stopped taking up CO 2 ) we have no idea how long it might have sat around before being used in a fire. Therefore, unfortunately, we cannot tell when the fire occurred with the limited data given. My Answer:

5. Current Carbon-14 Fraction Original Carbon-14 Fraction R = Measured with radioactivity or AMS methods Measured using a contemporary reference sample R

6. Warning! Astrophysicist Talking about Tree-Rings!

7. Correcting Carbon-14 With Tree Rings

8. Dendrochronology

9. Calibrating Carbon-14 Dates with Tree Rings

11. Estimated Age Estimated Ratio Current Carbon-14 Fraction Original Carbon-14 Fraction R = R

12. Estimated Age Actual Age Actual Ratio Estimated Ratio Current Carbon-14 Fraction Original Carbon-14 Fraction R = R

13. Atmospheric Carbon-14 fraction changes with time

14. The Changing Magnetic field

17. Calibrating Carbon-14 Dates with Tree Rings

20. Calibrated Carbon-14 Dates

23. Complications

25. The Early Americans

26. Warning! Astrophysicist Talking About Archaeology

27. Clovis Points

28. The Land Bridge

29. Clovis Mammoth kills Glaciers around 12,000 BP Clovis and the Ice-Free Corridor

30. The “Clovis-First” Model

31. Are there Sites earlier than Clovis?

32. Meadowcroft

33. The MeadowCroft Rockshelter

34. Dates at Meadowcroft

35. 1265 AD 980 BC -1305 BC 1260 BC - 6060 BC 1025 AD - 660 AD 1775 AD 340 BC - 870 BC 285 AD - 125 BC 10,850 BC - 14,255 BC +

36. Monte Verde

37. A Coastal Route?

38. What is really Important about Monte Verde

39. Monte Alegre

40. Temporal Relationships within a site

41. Temporal relationships between sites

42. Painted Caves from the Ice Age

43. Mammoth Hunters Forest Foragers How did people live in the New World? Rather than: How did people get into the New World?

44. Next Time Potassium, Argon, Genes and Walking Upright