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The Age of Things: Sticks, Stones and the Universe Correcting and Using Carbon 14 http://cfcp.uchicago.edu/~mmhedman/compton1.html
The Age of Things:Sticks, Stones and the Universe
Correcting and Using Carbon 14http://cfcp.uchicago.edu/~mmhedman/compton1.html
Last Time:
Current Carbon-14 FractionOriginal Carbon-14 FractionR =
Carbon-14 Fraction = Carbon 14All Carbon
R
A personal aside:
R
This says the tree from which thissample was taken was fallen ~14000 yrsago. However, (we) cannot judge this date asvalid w/o adequate context: Does this datemake 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 CO2) 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:
Current Carbon-14 FractionOriginal Carbon-14 FractionR =
Measured with radioactivity or AMS methods
Measured using a contemporary reference sample
R
Warning!AstrophysicistTalking aboutTree-Rings!
Correcting Carbon-14With Tree Rings
Dendrochronology
Calibrating Carbon-14 Dates with Tree Rings
Calibrating Carbon-14 Dates with Tree Rings
Estimated Age
Estimated Ratio
Current Carbon-14 FractionOriginal Carbon-14 FractionR =
R
Estimated Age
Actual Age
Actual Ratio
Estimated Ratio
Current Carbon-14 FractionOriginal Carbon-14 FractionR =
R
Atmospheric Carbon-14 fraction changes with time
The Changing Magnetic field
Calibrating Carbon-14 Dates with Tree Rings
Calibrating Carbon-14 Dates with Tree Rings
Calibrating Carbon-14 Dates with Tree Rings
Calibrated Carbon-14 Dates
Complications
Complications
The Early Americans
Warning!
Astrophysicist Talking About Archaeology
Clovis Points
The Land Bridge
Clovis Mammoth kills
Glaciers around 12,000 BP
Clovis and the Ice-Free Corridor
The “Clovis-First” Model
Are thereSites earlier thanClovis?
Meadowcroft
The MeadowCroft Rockshelter
Dates at Meadowcroft
Dates at Meadowcroft
1265 AD
980 BC -1305 BC
1260 BC - 6060 BC
1025 AD - 660 AD
1775 AD
340 BC - 870 BC285 AD - 125 BC
10,850 BC - 14,255 BC +
Monte Verde
A Coastal Route?
What is really Important about Monte Verde
Monte Alegre
Temporal Relationships within a site
Temporal relationships between sites
Mammoth Hunters
Forest Foragers
How did people live in the New World?
Rather than:How did people get into the New World?
Next Time
Potassium, Argon, Genes and
Walking Upright
