There can be problems encountered when dating cores (organic sediment fraction) that have been stored for long periods of time depending on the storage conditions. When cores are stored damp, contaminants like mold, mildew and other fungus can thrive and grow in the cores thereby introducing new carbon. Sometimes these mold, mildew and fungus get [...]
Eggshell can be dated – some had very reasonable dates, others not. The key factor is that the carbon present in the shell truly represented the time of life/death of the individual [or research subject] and is not of secondary origin.