Encyclopedia of scientific dating methods
My work focuses on the interface between chemistry and two other disciplines, geology and archaeology or paleoanthropology.
A relatively new way of determining the age of materials is to look at radiation damage caused by radioisotopes in the material itself and in its surroundings.
Techniques include tree rings in timbers, radiocarbon dating of wood or bones, and trapped charge dating methods such as thermoluminescence dating of glazed ceramics.
Coins found in excavations may have their production date written on them, or there may be written records describing the coin and when it was used, allowing the site to be associated with a particular calendar year.
Geological applications have included following the rise and fall of sea levels due to ice ages by dating shells of species known to live in shallow water, or looking at sediments buried by glaciers during ice ages.
Applications to archaeology and paleoanthropology cover the time range from New World flint artifacts to teeth and bones from million-year old sites associated with human evolution.
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.
Absolute dating provides a numerical age or range in contrast with relative dating which places events in order without any measure of the age between events.
In archaeology, absolute dating is usually based on the physical, chemical, and life properties of the materials of artifacts, buildings, or other items that have been modified by humans and by historical associations with materials with known dates (coins and written history).
Sites I have studied include Olduvai Gorge in Tanzania to look at early human evolution, Iringa in Tanzania to estimate the evolutionary history of our own speices, Mesmaiskaya Cave in Russia where there may have been overlap of modern humans and Neanderthals, and Moendas Cave in Brazil, location of the oldest human skeletal remains in the Western Hemisphere. An exciting application here has been the study of burnt bones from South Africa.
Evidence shows that they had to be heated in a campfire.