Abstract

Three Normal and three Reversed palaeomagnetic polarity zones were identified in the exposed 67 m section of Mercia Mudstone at St Audrie’s Bay, Somerset, which has been regarded as being of Norian age on limited biostratigraphic evidence. The polarity sequence is correlated with magnetozones E15 to E17 in the Newark Basin, New Jersey, further supporting the inferred Norian age and tentatively placing it in the mid-Norian. Correlations with the northern North Sea and the Alps are also suggested. Results from Doniford Bay, where tectonic dips are steeper but which cannot be correlated precisely with the St Audrie’s section, are incorporated for the calculation of the mean direction of Characteristic Remanent Magnetization which has declination 30.8° and inclination +34.3° (N=27 horizons, α₉₅ = 5.1°). The corresponding palaeomagnetic pole is 49.6°N, 128.4°E (dp = 3.3°, dm = 5.8°), which also correlates with the Norian of the Newark Basin, while possibly indicating that small adjustments should be made to the orientation of all or part of Britain within the 1965 Bullard et al. configuration as a representation of Late Triassic geography.