RECENT studies by J. Hospers1 have revealed that Icelandic basalts fall into two groups with respect to their remanent magnetization. In one group the direction of magnetization is close to the present direction of the geomagnetic field. In the other group the magnetization has the opposite direction. Intermediate directions are rarely found. Studies made by A. Roche2 have revealed the same fact for French basalts of Quaternary and Tertiary age. These findings have been interpreted in terms of repeated reversals of the geomagnetic field.