The total mass of the isotope is indicated by the numerical superscript.
While the lighter isotopes C has decayed that what remains can no longer be measured. In 5,730 years half of the C in the atmosphere, and therefore in plants and animals, has not always been constant.
These rocks normally form relatively horizontal, parallel layers, with younger layers forming on top.
Professor Willard Libby produced the first radiocarbon dates in 1949 and was later awarded the Nobel Prize for his efforts.
Radiocarbon dating works by comparing the three different isotopes of carbon.
Each unique archival collection has a finding aid that provides the user with varying levels of descriptive detail about the collection, such as creator, biographical or historical note, content, subjects, names, forms of materials, how the collection is arranged, the context in which the collection was created, related collections in individual repositories and across the Smithsonian, provenance, where the collection is housed, and how to access the collection.
Digitized content from each collection is also accessed via links provided in the collection's finding aid.
The layers of sedimentary rock, or strata, can be seen as horizontal bands of differently colored or differently structured materials exposed in this cliff.