Geologists do not use carbon-based radiometric dating to determine the age of rocks. Carbon dating only works for objects that are younger than about 50,000 years, and most rocks of interest are older than that. Over time, carbon-14 decays radioactively and turns into nitrogen.

What materials are best dated with carbon-14?

Radiocarbon dating is best used for biological artifacts that originally got their carbon from atmospheric carbon dioxide and are less than 50 000 years old.

How is C-14 created?

Carbon-14 is continually formed in nature by the interaction of neutrons with nitrogen-14 in the Earths atmosphere; the neutrons required for this reaction are produced by cosmic rays interacting with the atmosphere.

What are the negative effects of using carbon-14?

The major concern for individuals working with this isotope is the possibility of an internal exposure. Such an exposure may occur if an individual contaminates bare skin, accidentally ingests the material, or breathes it in the form of a gas or vapor (usually radioactive CO2).