Start C dating

C dating

One of the nice things about this method is that we don't have to worry about carbon being lost from the sample.

Another source of old carbon is the outgassing from volcanoes: in locations where this is a significant source of CO, plants growing in the area will appear older than they actually are.

Even participation in the terrestrial carbon cycle does not quite guarantee the date: we could, for example, imagine termites eating their way through the wood of a 200 year old house; these termites would date to 200 years old or more (depending on the age of the tree).

Two effects also interfere with the dating of very recent samples.

The testing of thermonuclear weapons produced an increase in atmospheric C they contain is infinitesimal.

After the death of the organism, processes of decay will return its carbon to the atmosphere, unless it is sequestered — for example in the form of coal.

This means that when an organism is alive, its ratio of C dating, or C-C dating.

Also it is obviously possible to carbon-date one of the growth rings of a tree, and to compare the date produced by radiocarbon dating with the date produced by dendrochronology.

Such dates typically agree to within 1 or 2 per cent.

Fortunately it is rarely necessary to use radiocarbon methods to date very recent samples.

Thirdly, it is in the nature of the method that it can only be applied to organic remains: it makes no sense to apply it to rocks or to mineralized fossils.

Fourthly, the carbon in the organic remains does have to originate with the terrestrial carbon cycle and with plants performing photosynthesis.