dating: Absolute Dating. The varved-clay technique is used with reasonable precision on deposits as much as 12,000 yrs . old.
Absolute dating can be performed with the use of historical documents and through the analysis of biological and geological habits ensuing from yearly climatic variants, such as for instance tree bands (dendrochronology) and varve analysis. Since 1950 the real sciences contributed lots of absolute dating techniques that experienced an effect that is revolutionary archaeology and geology. These methods are based on the dimension of radioactive procedures (radiocarbon; potassium-argon, uranium-lead, uranium-thorium, thorium-lead, etc.; fission track; thermoluminescence; optically stimulated luminescence; and electron-spin resonance), chemical procedures (amino-acid racemization and obsidian moisture), therefore the magnetic properties of igneous product, cooked clay, and sedimentary build up (paleomagnetism). Other methods are now and again helpful, as an example, historic or iconographic sources to datable astronomical occasions such as for instance solar eclipses (archaeoastronomy).