Remanent, induced, and total-magnetic properties are measured for a suite of specimens from a north-trending ring dike, Buell Park, Arizona. The direction of remanent magnetism is essentially across the dike in an easterly or westerly direction and has low-angle positive or negative inclinations. The remanent magnetism has an average value of 3.10 (super -3) emu/cm 3 . The total magnetism is controlled in part by the remanent magnetism. A ground-magnetometer survey, with anomalies exceeding 10,000 gammas, was made for the area and profiles are presented. The results of these measurements, which suggest a shallow magnetization, are correlated with rock-magnetic measurements with good agreement. . . . Variability of the remanent magnetism is related to a magnetism acquired after the thermal-remanent magnetism of the rocks and most likely is related to a secondary magnetization caused by lightning.