Correlatives of the Greta Coal Measures in the Hunter Valley and Gunnedah Basin, New South Wales

Abstract

Exposures of Early Permian strata in the Gunnedah Basin are described and it is shown that the Willow Tree, Werris Creek, Condadilly, and Wean Formations comprise similar successions consisting of prominent horizons of kaolinite clayrocks or flint clays at the base overlain by quartz‐lithic sandstone, siltstone, and conglomerate. It is concluded therefore that these formations pertain to the same stratigraphic unit and, since the flint clays do not differ appreciably from those characterizing the Greta Coal Measures at Wingen, that this stratigraphic unit represents extension of the measures in the Gunnedah Basin. The Willow Tree and Wean Formations are underlain by considerable thicknesses of kaolinitic soil that undoubtedly furnished the detritus for the alluvial and colluvial flint clay deposits. The presence of the soil indicates that during part of the Early Permian in northeastern New South Wales the climate was humid and at least subtropical.