Overheard a guy at a dig site say carbon dating is just 'educated guessing'

I was volunteering at a small site in Vermont last weekend and this older volunteer said carbon dating is basically a glorified guess because contamination ruins everything. He said he once got a date off a piece of charcoal that was 2000 years off just because of root intrusion. Has anyone else run into data that was way off from carbon dating issues?

2 comments

2 Comments

leelewis6d ago

Dealt with this exact problem back when I was helping out on a dig in Pennsylvania. We had a fire pit area that tested at 4000 years old from one sample and then 1500 years from another piece from the same layer. Turned out a tree root had grown right through the older ash and pushed in some younger carbon. So yes, contamination is a real issue but good labs know to look for root fibers and other junk. They'll screen the sample first and can often tell when something is off. The trick is to always take multiple samples from different spots and never trust a single date.

caseywest5d ago

Multiple samples can lead to multiple wrong answers. Sometimes the contamination is uniform across the whole layer and every sample reads the same wrong date. Seen it happen. Three samples all said 3000 BC and it turned out to be a coal seam leaching old carbon into the whole area.