"They call me anytime things are large and we need to lead an excavation."Since work on the extension began in 2014, fossilized remains have routinely turned up from creatures that roamed the grasslands and forests that covered the region during the last Ice Age, about 10,000 years ago.

age dating of fossils-45

When her phone buzzes, she quickly dons a neon vest, hard hat and goggles before climbing deep down into a massive construction site beneath a boulevard east of downtown.

Earth-movers are diverted, and Leger gets on her hands and knees and gently brushes the dirt from a spot pointed out by a member of her team.

Where t is the age of the fossil (or the date of death) and ln() is the natural logarithm function.

If the fossil has 35% of its carbon 14 still, then we can substitute values into our equation.

Her heart beats faster because there's a chance she'll uncover what she calls "the big find."Leger is a paleontologist who digs for fossils in the middle of a city rather than an open plain or desert.

She works for a company contracted by Los Angeles transportation officials to keep paleontologists on hand as workers extend a subway line to the city's west side."They're making sure that they're recovering every single fossil that could possibly show up," Leger says of her team of monitors.

Carbon is naturally in all living organisms and is replenished in the tissues by eating other organisms or by breathing air that contains carbon.

At any particular time all living organisms have approximately the same ratio of carbon 12 to carbon 14 in their tissues.

In the case of radiocarbon dating, the half-life of carbon 14 is 5,730 years.