When the carbon-12 to carbon-14 ratio has not been constant in the atmosphere over time?
http://adsabs.harvard.edu/abs/1971RSPSA.321..105B
“Variations in atmospheric carbon-14 concentrations during the past century have been studied through the analyses of wines, spirits and plant seeds. The results reveal that short-term fluctuations of carbon-14 concentrations have occurred which are negatively correlated with solar activity.”
http://www.time.com/time/magazine/ar...7461-1,00.html
“But as the number of puzzling carbon 14 dates increased, scientists at the universities of Arizona, Pennsylvania and California began testing Libby's assumption by turning to some of the oldest living things on earth—California's bristlecone pine and sequoia trees, which have been growing for as long as 4,000 years. By carefully analyzing the carbon 14 content in the annual growth rings of the trees, they found that there have, in fact, been small but significant changes in the isotope's production over the centuries, apparently as a result of variations in the cosmic-ray bombardment.”
When the carbon-14 that is created is not evenly distributed among living things?
http://geography.otago.ac.nz/Courses...bonDating.html
“Organic specimens drawing carbon from reservoirs other than the atmosphere may yield incorrect ages. In the case of marine shells deriving their carbon from seawater, a system not in equilibrium with the atmosphere, the reservoir effect can lead to age differences of up to 1000 years. This difference can be reflected in bones of animals or humans consuming fish. High apparent ages can be found in plants near volcanoes erupting 14C-depleted CO2. Other small age shifts arise from differences in atmospheric mixing between northern and southern hemispheres, and regional air-sea exchange of CO2.”
When radiocarbon dates and tree ring dates are not in agreement?
Egypt’s 18th Dynasty is dated to around 1500-1400 BC according to what is generally believed about written records and artifacts. But http://www.atlantisrising.com/issue11/ar11carbon.html wood taken from the tomb of Tutankamun, one of the last 18th Dynasty pharaohs was found to have a carbon date of around 1050 BC. (I seen some claims that materials from Tut’s tomb have carbon dates as recent as the 8th century BC.)
http://www.diveturkey.com/inaturkey/uluburun/dendrochron.htm
Back in the 1990s a shipwreck was found off the coast of Turkey. A piece of wood that is thought to be part of the ship’s hull has a tree-ring date of 1441 BC give or take 37 years.
But a piece of firewood from the wreck has a tree-ring date of only 1356 BC give or take 37 years.
The wreck also yielded a gold scarab from Egypt that had the name Nefertiti, the wife of Pharaoh Aknaton. The scarab is worn, suggesting that it may been a keepsake and thus dates the shipwreck to sometime after Aknaton’s time (roughly 1350-1330 BC if you accept the conventional chronology).
But even if the shipwreck happened even a generation after Aknaton, the tree ring dates don’t support a 1050 BC (let along an 8th century BC) carbon date for Tut.
When the decay rate is not constant?
Things like temperature and barometric pressure can alter the results of a radiocarbon dating test: http://www.aip.org/history/climate/Radioc.htm. Now, if radiocarbon isn’t a reliable dating method under laboratory conditions, how can we expect radiocarbon to behave in a constant way in the real world and thus give accurate dates?
http://adsabs.harvard.edu/abs/1971RSPSA.321..105B
“Variations in atmospheric carbon-14 concentrations during the past century have been studied through the analyses of wines, spirits and plant seeds. The results reveal that short-term fluctuations of carbon-14 concentrations have occurred which are negatively correlated with solar activity.”
http://www.time.com/time/magazine/ar...7461-1,00.html
“But as the number of puzzling carbon 14 dates increased, scientists at the universities of Arizona, Pennsylvania and California began testing Libby's assumption by turning to some of the oldest living things on earth—California's bristlecone pine and sequoia trees, which have been growing for as long as 4,000 years. By carefully analyzing the carbon 14 content in the annual growth rings of the trees, they found that there have, in fact, been small but significant changes in the isotope's production over the centuries, apparently as a result of variations in the cosmic-ray bombardment.”
When the carbon-14 that is created is not evenly distributed among living things?
http://geography.otago.ac.nz/Courses...bonDating.html
“Organic specimens drawing carbon from reservoirs other than the atmosphere may yield incorrect ages. In the case of marine shells deriving their carbon from seawater, a system not in equilibrium with the atmosphere, the reservoir effect can lead to age differences of up to 1000 years. This difference can be reflected in bones of animals or humans consuming fish. High apparent ages can be found in plants near volcanoes erupting 14C-depleted CO2. Other small age shifts arise from differences in atmospheric mixing between northern and southern hemispheres, and regional air-sea exchange of CO2.”
When radiocarbon dates and tree ring dates are not in agreement?
Egypt’s 18th Dynasty is dated to around 1500-1400 BC according to what is generally believed about written records and artifacts. But http://www.atlantisrising.com/issue11/ar11carbon.html wood taken from the tomb of Tutankamun, one of the last 18th Dynasty pharaohs was found to have a carbon date of around 1050 BC. (I seen some claims that materials from Tut’s tomb have carbon dates as recent as the 8th century BC.)
http://www.diveturkey.com/inaturkey/uluburun/dendrochron.htm
Back in the 1990s a shipwreck was found off the coast of Turkey. A piece of wood that is thought to be part of the ship’s hull has a tree-ring date of 1441 BC give or take 37 years.
But a piece of firewood from the wreck has a tree-ring date of only 1356 BC give or take 37 years.
The wreck also yielded a gold scarab from Egypt that had the name Nefertiti, the wife of Pharaoh Aknaton. The scarab is worn, suggesting that it may been a keepsake and thus dates the shipwreck to sometime after Aknaton’s time (roughly 1350-1330 BC if you accept the conventional chronology).
But even if the shipwreck happened even a generation after Aknaton, the tree ring dates don’t support a 1050 BC (let along an 8th century BC) carbon date for Tut.
When the decay rate is not constant?
Things like temperature and barometric pressure can alter the results of a radiocarbon dating test: http://www.aip.org/history/climate/Radioc.htm. Now, if radiocarbon isn’t a reliable dating method under laboratory conditions, how can we expect radiocarbon to behave in a constant way in the real world and thus give accurate dates?
