A new scalar magnetic anomaly map derived from Magsat data at high northern latitudes shows important correlations with major geologic and tectonic features. Positive magnetic anomalies over some high-grade metamorphic Precambrian terranes contrast with negative anomalies over lower-grade Precambrian terranes. A positive anomaly is associated with the Aleutian arc-trench system, a region of active plate convergence. Negative anomaly fields are associated with the Nansen-Gakkel Ridge, a region of plate accretion in the Arctic Basin, with its extension into the seismically active Cherskly Mountains in eastern Siberia, and with the Labrador Sea, an extinct spreading center. However, a positive anomaly occurs over Iceland, on the mid-Atlantic spreading ridge system, and an intense positive anomaly occurs over the Alpha Ridge in the Arctic Basin. The relations among the Magsat orbit, the rotation of the earth, and the movements of the auroral oval have major effects on th spatial distribution of acceptable data and, therefore, on map resolution.