Paleomagnetic directions have been determined from well-dated Precambrian rocks, in large part mafic dikes, in Wyoming, Montana, and Arizona. Ages, determined radiometrically, range from 700 to 2,550 m.y. When these data, together with the compilation of acceptable well-dated paleomagnetic poles from North America, are treated by a running-mean method, a generalized belt of apparent polar wandering is suggested. This belt is simple in form, and the rate of polar wandering is nearly uniform. The existence of large-scale loops of relatively rapid wander velocity is largely unsupported.

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