Lower Purbeck Beds of Swindon Facies in Dorset

Abstract

IN the course of a yet unpublished study of the pseudomorphs after gypsum prevalent in the ‘Purbeck Caps’ and ‘Broken Beds’ of Lower Purbeckian age in Dorset, a marl has been discovered with a fauna resembling that of the freshwater facies of the ‘Swindon Series’. In the well-known Portisham quarry with the ‘fossil elephant’ (a silicified tree trunk1), the three-foot “impure marls with seams of chert” listed by Woodward1 as occurring 9 ft. 6 in. above the Portland Stone have been found to contain the Swindon ostracod Ulwellia papulata Anderson, and well-preserved charophytes in abundance. Gastropods are also abundant and perhaps have Swindon affinities. None of these has been recorded before in British strata of indisputably Lower Purbeck age, and a full palseontological investigation of the fauna is at present proceeding.