An Experimental Study of Palaeosecular Variation

Abstract

A total of 83 selected palaeomagnetic results are used in a latitude analysis of palaeosecular variation to show that Cox's 1970 model for secular variation fits the data, provided the dipole wobble is between 1½° and 2°. The major contribution to secular variation then arises from the joint effect of dipole oscillations with the non‐dipole terms. The parameters required to produce this effect are in accord with those used in Cox's 1968 model for reversal frequency. In time, secular variation for the pre‐Tertiary is about 15 per cent smaller than during the Tertiary. An alternative approach using large equatorial collections confirms that palaeosecular variation must be due to a combination of dipole wobble, dipole oscillations, and non‐dipole effects, with dipole wobble again making only a small contribution. Copyright © 1971, Wiley Blackwell. All rights reserved