My big mistake with radiocarbon dating in Colorado

I was working on a dig site near Durango a few months ago and kept getting weird dates on some bone fragments. They were way older than they should have been based on the layers around them. After pulling my hair out for a week, a buddy told me to check if the bones were boiled by ancient people. Sure enough, a quick microscopic look showed collagen damage from boiling, which can mess up the carbon dates. Has anyone else run into cooking contamination throwing off their results?

3 comments

3 Comments

the_claire2d ago

Makes you wonder what other everyday activities leave hidden traces we never notice, right @milarodriguez?

evan_green521d ago

Man I feel your pain, I once spent three weeks chasing a ghost date on what I thought was a pristine elk bone only to find out later it had been in a stew pot the night before I found it! That collagen damage is sneaky stuff, boiling literally rearranges the carbon structure like some kind of mad scientist experiment. My trick now is to just assume everything's been cooked unless proven otherwise, call it the "burnt dinner rule" from my own kitchen disasters. Sediment samples are a great call too, I started doing those after a layer of volcanic ash made my dates look like they came from the dinosaur era. At least now we know to check for cooking before we embarrass ourselves in front of the whole department! Makes me wonder what other dumb mistakes I've made that I just haven't caught yet.

milarodriguez2d ago

Id start by checking the collagen condition before dating if there is any chance the bones were cooked. Boiling is a common contamination source, but even heat from campfires can mess with the carbon ratio. You might also want to run a sample of the sediment from the same layer just to rule out other factors.