To an archaeologist examples of relative dating methods include
Sir Flinders Petrie had worked out a formula for dating the finds on the basis of the thickness of the deposit.
According to him a period of hundred years may be granted for the accumulation of a deposit of one and a half feet.
Specimens of organic material which can yield good amount of carbon can be collected for C-14 dating.
For example charcoal, wood, shell, paper, leaves, cloth, animal hair, bone, pollen, tooth, iron, prehistoric soot from the ceiling of the caves practically any material containing some carbon can be subjected Bones are generally affected by ground water carbonates and are therefore least reliable for dating.
This closely agrees with the fact that the seals from Indus Valley style from Ur, Kish and Tell Asmar and other sites fall within the range of 2500-1500 B. When a group or type of objects are found together under circumstances suggesting contemporanity they are said to be associated.
It is nearly always association with other phenomena that gives a first clue as to the use, the age and chronological attribution of a potential datum, but age at least may sometimes be inferred from position in a geological deposit or a layer of peat.
With the aid of these dated imports it was possible to date the associated Indian objects to the first two centuries A. Similarly NBP and PGW has helped in fixing the chronology of numerous sites. Sometimes dates are also obtained with the assistance of astronomy.
The quantity of the C-14 remaining is measured by counting the beta radiation emitted per minute per gram of material.
Modern C-14 emits about 15 counts per minute per gram, whereas Carbon-14 which is 5700 years old, emits about 7.5 counts per minute per gram.
Quite convincing dates are sometimes arrived at by importing parallels from other contemporaneous cultures.
This parallelism is formed due to trade relations, particularly wehen trade followed in both directions.