Relative dating methods in archaeology
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.The deposit thus occurring forms layers depending on the nature of the material brought in by the people inhabiting the area.According to this method, the upper deposits are younger and the lower deposits are older.For example, beads closely resembling those from the temple repositories at Cnoss and dating from C.1600 B.C were found in a late context (Period V) at Harappa. By noting the association of these beads it has been possible to trace a archaeological datum line across Indian sub-continent and Mesopotamia.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.
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.However this formula has not been accepted by many archaeologists.Further this formula has been disproved on many occasions. Pottery is probably the most abundantly available antique material in any archaeological site.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.