SNN107489 - A Re-Investigation of the Scientific Dating Evidence From the Hillfort at Rainsborough

A chronological framework is an integral part of any archaeological interpretation but it is often restricted by the lack of precision in the dates available to the archaeologist. This is a particular problem in the Iron Age, due to the limitations of radiocarbon dating in this period; specifically the period between 700-400BC where the radiocarbon calibration curve provides large errors. Archaeomagnetic dating is predominately a method of dating materials that have been heated in antiquity. Therefore archaeomagnetic studies offer an underexploited opportunity to provide dates for the Iron Age through the study of past geomagnetic field, as recorded by archaeological materials. As with radiocarbon, archaeomagnetic dating requires a calibration curve to provide calendar dates. However, in order to produce a calibration curve it is necessary to assign a calendar date to every magnetic direction used to construct it. One of the main problems with the current method of calibrating magnetic directions is the imprecision of the calendar dates attributed to the magnetic direction determinations used in it. This ongoing research is attempting to improve on the independent dating associated with each data point in the current calibration curve. Unlike radiocarbon dating, there is evidence that the direction of the geomagnetic field was undergoing rapid changes between 700-100BC, so archaeomagnetism should be capable of high resolution dating during this period. This paper describes how evidence from the Iron Age hillfort at Rainsborough is being used to improve the current archaeomagnetic calibration curve for the UK.