A dip-needle survey of a heavily drift-covered part of the Keweenawan copper district of northern Michigan, in which there are few outcrops, was undertaken in an effort to trace the major Keweenawan units beneath the drift. Small but persistent variations in dip-needle readings made it possible to locate several belts of basic flows, and to trace a number of faults and shattered zones. From the dip-needle readings, a geologic map was prepared. Interpretation of this map indicates that a large part of the Keweenawan series is present in the area, including horizons from the Baltic, or lower, to the Great conglomerate, and that the Keweenaw fault is cutting higher into the series to the southwestward, eliminating some of the lower horizons.

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