Fig. 1

Geomagnetic directional variations in Western Europe (all data reduced to Paris) over the past 1000 years as constrained from archeomagnetic results, direct historical magnetic measurements and field modeling. Individual archeomagnetic data from AD 1500 to 1700 are shown in gray, whereas the orange curve displays the average French archeomagnetic variation curve according to Bucur (1994). The dark-blue curve exhibits the historical geomagnetic variations spanning the past four centuries estimated at Paris by Thellier (1981) from a selection of D, I measurements from Paris, London and Rome. The black curve from Malin and Bullard (1981) expresses the directional variations at Paris when considering only the D, I measurements made in London. The brown and white curves show the evolution in magnetic direction expected in Paris from two global field models constructed by Thomson and Barraclough (1982) and Jackson et al. (2000), respectively