Comparison of Directional Secular Variation of the Geomagnetic Field between Britain and S. E. Europe.

Abstract

Archaeomagnetic data from “Britain” (46°N-58°N, 12°W-8°E) and S. E. Europe (37°N-49°N, 15°1-25°E) for the last 2, 300 years are selected on the basis of the reported reliability of their archaeological age as well as the precision in the determination of their mean site values. When grouped into mean values for each decade, clear trends are visible for both areas, although individual sites show somewhat anomalous values that are largely attributed to in situ site disturbances. The trend lines, when smoothed by a two-point running mean, appear to give a good representation of the geomagnetic secular variation in these two areas. Comparison between the areas, that are 9° in latitude and 26° longitude apart, suggests that an axial geocentric dipole could largely account for the average difference in inclination. The quasi-sinusoidal patterns are more complex in declination than inclination, as previously proposed on less reliable data. There are visual indications of periodicities of some 300 years in inclination and some 400 years in declination but periodicities longer than the time range represented by the data are present. The time of occurrence of maxima and minima for both declination and inclinations suggests that both westward and eastward drift of the geomagnetic field patterns have occurred.