Problems with carbon dating accuracy
(Since humans have only existed in the Americas for approximately 12,000 years, this is not a serious limitation to southwest archaeology.) Radiocarbon dating is also susceptible to contamination.
If the ground in which an object is buried contains particles of coal or other ancient sources of carbon, radiocarbon testing may indicate that the object is far older than it really is.
Carbon-14 dating does not produce ages in the millions of years, as do some other types of radioisotope dating.
C dating consists of measuring the amounts of carbon-14 and carbon-12, and sometimes C-13, in a sample.
Carbon has an atomic number of 6, an atomic weight of 12.011, and has three isotopes: carbon-12, carbon-13, and carbon-14.
(The numbers 12, 13 and 14 refer to the total number of protons plus neutrons in the atom's nucleus.
This turns out not to be exactly true, and so there is an inherent error between a raw "radiocarbon date" and the true calendar date.
To correct for this, scientists have compared radiocarbon dates from objects who's age is known by other means, such as artifacts from Egyptian tombs, and growth rings from ancient trees.
It can theoretically be used to date anything that was alive any time during the last 60,000 years or so, including charcoal from ancient fires, wood used in construction or tools, cloth, bones, seeds, and leather.
This can be done very accurately, although some samples may be difficult to work with.