How do scientists figure out how old an archeological find is?
   Elena, Age 11, Kentucky

Dr. dig responds:
To figure out the age of an archaeological find, scientists look at both the place where it was found (its context and stratigraphy [the level at which it was found]) and at the find itself. If the find has come from a well-excavated site, it may be possible to date it by its association with other objects, some of which may actually have dates written on them, or by reference to the surrounding sand or soil. If that's not possible, it's time to call in the experts. All types of finds have their own specialist: There are stone experts, bone experts, pottery experts and so on. They will use a variety of techniques to get a date. A pottery expert, for example, will study the shape, clay, and contents of a pot, and may well use thermoluminescence dating (an analysis of the radioactive particles contained within the fired clay) to get a firm date.