Assessing the fidelity of palaeomagnetic records of geomagnetic reversal

A major difficulty facing the study of geomagnetic polarity reversals lies in interpreting palaeomagnetic records of polarity transitions. These recor ds are the sole source of information about what happens to the field as it reverses. In addition to comparison of records of the same reversal from d ifferent types of recorders to check for accuracy, we need some internal me asure that can be used as a gauge of the temporal resolution provided by th e data. This paper explores methods using the extent to which secular varia tion is recorded in the full polarity intervals bounding polarity transitio ns to estimate the temporal extent to which the transitional record should be interpreted. Cumulative dispersion and two autocorrelation methods are e valuated using datasets representative of different end-member palaeomagnet ic records of secular variation and polarity transitions.