Can radiocarbon dating be used on rocks
Through photosynthesis carbon dioxide enters plants and algae, bringing radiocarbon into the food chain.Radiocarbon then enters animals as they consume the plants (figure 2).After plants and animals perish, however, they no longer replace molecules damaged by radioactive decay.Instead, the radiocarbon atoms in their bodies slowly decay away, so the ratio of carbon-14 atoms to regular carbon atoms will steadily decrease over time (figure 3).Radiocarbon (carbon-14 or C) forms continually today in the earth’s upper atmosphere.And as far as we know, it has been forming in the earth’s upper atmosphere at least since the Fall, after the atmosphere was made back on Day Two of creation week (part of the expanse, or firmament, described in Genesis 1:6–8). Cosmic rays from outer space are continually bombarding the upper atmosphere of the earth, producing fast-moving neutrons (sub-atomic particles carrying no electric charge) (figure 1).1 These fast-moving neutrons collide with nitrogen-14 atoms, the most abundant element in the upper atmosphere, converting them into radiocarbon (carbon-14) atoms.Let’s suppose we find a mammoth’s skull, and we want to date it to determine how long ago it lived.
The radiocarbon half-life or decay rate has been determined at 5,730 years.
A child mummy is found high in the Andes and the archaeologist says the child lived more than 2,000 years ago.
How do scientists know how old an object or human remains are?
If we assume that the mammoth originally had the same number of carbon-14 atoms in its bones as living animals do today (estimated at one carbon-14 atom for every trillion carbon-12 atoms), then, because we also know the radiocarbon decay rate, we can calculate how long ago the mammoth died. This dating method is also similar to the principle behind an hourglass (figure 4).
The sand grains that originally filled the top bowl represent the carbon-14 atoms in the living mammoth just before it died.
It’s assumed to be the same number of carbon-14 atoms as in elephants living today.