Carbon dating article
This family of dating methods, some more than a century old, takes advantage of the environment’s natural radioactivity.
Certain unstable isotopes of trace radioactive elements in both organic and inorganic materials decay into stable isotopes. By measuring the proportion of different isotopes present, researchers can figure out how old the material is.
A submethod within biostratigraphy is faunal association: Sometimes researchers can determine a rough age for a fossil based on established ages of other fauna from the same layer — especially microfauna, which evolve faster, creating shorter spans in the fossil record for each species.
Paleomagnetism: Earth’s magnetic polarity flip-flops about every 100,000 to 600,000 years.
These methods — some of which are still used today — provide only an approximate spot within a previously established sequence: Think of it as ordering rather than dating.
Biostratigraphy: One of the first and most basic scientific dating methods is also one of the easiest to understand.
Carbon 14 is another, an isotope of carbon that is produced when Nitrogen (N-14) is bombarded by cosmic radiation.Methods fall into one of two categories: relative or absolute.Before more precise absolute dating tools were possible, researchers used a variety of comparative approaches called relative dating.The polarity is recorded by the orientation of magnetic crystals in specific kinds of rock, and researchers have established a timeline of normal and reversed periods of polarity.Paleomagnetism is often used as a rough check of results from another dating method.
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On the other hand, atmospheric testing of nuclear weapons during the 1950s and 1960s is likely to have increased the Carbon 14 content of the atmosphere.