Recent radiocarbon dating
paleobotanist for plants, forensic archaeologist for bones, or paleontologists for shells.Generally, it is better to date the macrofossils present than the sediment due to the possible contaminants in the latter.In general the plant dates are usually more reliable as they typically represent a more unique event in time.The plants were relatively short-lived as compared to the time it may have taken for the sediment to form.Most macrofossils can be treated with (1) acid to remove carbonates, and (2) alkali to remove humic acids that might be in the sediment. Sediment and rain water or ground water can move these humic acids up or down through the sedimentary profile bringing carbon that is either younger or older into a sediment layer.
The source of this carbon can be from more recent humic and fulvic acids or ancient labile carbon that is alkali-soluble.
– Sediments are complex systems containing carbon of multiple forms, sizes ranges and sources.