Ancient history dating methods
Astronomical data have been applied in the study of geological ice ages by calculating the curves for major fluctuation of solar radiation.Consequently, the chronology worked out for the geological deposits helped in dating the prehistoric tools found in these deposits. There are certain antiquities and potteries which by themselves have acquired a dating value.
But, even when the scientific methods of absolute dating are available, this method of dating has not lost its importance, as many a time we have to depend solely on relative dating.Once a type has been classified by the aid of its context further specimen of the same type, even when found in isolation, can be assigned their place in terms of dates.Association in simplicity can be illustrated by an example, at the port of Arikamedu near Pondicherry.Carbon-14, or radiocarbon, is a naturally occurring radioactive isotope that forms when cosmic rays in the upper atmosphere strike nitrogen molecules, which then oxidize to become carbon dioxide.Green plants absorb the carbon dioxide, so the population of carbon-14 molecules is continually replenished until the plant dies.Carbon-14 is also passed onto the animals that eat those plants.
After death the amount of carbon-14 in the organic specimen decreases very regularly as the molecules decay.
Until this century, relative dating was the only technique for identifying the age of a truly ancient object.
By examining the object's relation to layers of deposits in the area, and by comparing the object to others found at the site, archaeologists can estimate when the object arrived at the site.
Carbon-14 has a half-life of 5,730 ± 40 years, meaning that every 5,700 years or so the object loses half its carbon-14.
Samples from the past 70,000 years made of wood, charcoal, peat, bone, antler or one of many other carbonates may be dated using this technique.
For example, beads closely resembling those from the temple repositories at Cnoss and dating from C.1600 B.