Abstract

A computer listing of paleomagnetic polarities available up to the end of 1973 has been used to generate a reversal time-scale for the Mesozoic and late Paleozoic. The main source of error is in the ages of beds, and age ranges, rather than single ages, are assigned and the results within that range distributed uniformly. Of great importance are the polarity superintervals of essentially uniform polarity in the late Palaeozoic, Late Triassic to Early Jurassic, Mid-Jurassic, and Mid-Cretaceous (superintervals LP, TJ, J and K respectively). Superinterval J is of special interest because of the need to determine the age and origin of the marginal quiet zones. The best estimate of its age is —164 to —150 m.y. The boundaries of superintervals provide world-wide synchronous levels for stratigraphic purposes, both on land and at sea.