Abstract

Dr M. G. Audley-Charles in a written contribution referred to Mr Warrington's interpretation of the palaeocurrent directions in the Keuper Sandstone. Mr Warrington had suggested the presence of westward-flowing rivers near the western margin of the Pennine uplands in Staffordshire, and had gone on to argue that this indicated that a barrier existed during Keuper Sandstone deposition between the Pennine uplands and the London–Brabant massif uplands, so that the Yorkshire–North Sea basin was isolated from the Worcester graben during this time. Dr Audley-Charles did not wish to dispute the importance of westward-flowing streams in this region, but suggested that palaeocurrent directions were insufficient evidence for erecting a barrier to isolate these two adjacent regions of accumulating sediments. He also reminded Mr Warrington that Swinnerton (1918) had found palaeocurrent directions indicating a river flowing from west to east near Nottingham during the deposition of the Keuper basement beds.

Dr J. D. Hudson asked if Mr Warrington could say a little more about the criteria he used to distinguish between marine and non-marine faunas and floras in the Keuper deposits he had described, and in particular enquired about the significance of Euestheria as an environmental indicator. If, as some speakers had suggested, formational boundaries in the centres of the Triassic basins were commonly concordant with palaeontological zones (not diachronous), it was conceivable that the faunas and floras, as well as the lithologies, were controlled by environmental changes and were not strictly related to time. He asked for Mr Warrington's views