The Jotunheim Massif of Precambrian granu-lite-facies rocks lies on the southeastern side of the Norwegian Caledonides. Although the geological evidence suggests that it is a far-travelled nappe derived from an internal zone to the northwest, a gravity anomaly of +58 mgals indicates that it is underlain by dense rocks to a depth of 10–15 km, which might form a local root-zone (Smithson et al. 1974). The structural evidence described from the thrust-zone forming the northwestern margin of the massif indicates that the early movements on this boundary were directed towards the southeast. Since southeasterly movements also occurred on the low-angle overthrusts which form its southeastern margin, the Jotunheim Massif is clearly allochthonous, derived by overthrusting from the northwest.