INTERTIDAL SEDIMENTS AND TRACE FOSSILS FROM THE WATERSTONES (SCYTHIAN–ANISIAN?) AT DARESBURY, CHESHIRE

SUMMARY In a facies and trace fossil analysis of the Waterstones in North Cheshire, five gradational lithofacies are recognised: A—discontinuous bodies composed of lenticular units of cross-bedded, medium to fine sandstone: B—thin-bedded, muddy, fine sandstone with interbedded shale: C—thinner sandstones interlaminated with flaser-bedded siltstone or mudstone: D—shale: E—silty mudstone (‘marl’). Trace fossils described are: Thalassinoides cf. suevicus, Diplocraterion luniforme, Arenicolites sp., cf. ‘ Scoyenia?’ triadica, Planolites, Isopodichnus, looped trails and vertebrate footprints. This ichnocoenosis can be assigned primarily to the Skolithos — Glossifungites ichnofacies, which represents the earliest stratigraphical evidence of marine conditions so far described from the English Trias. The Scoyenia ichnofacies is represented also. The depositional environment was intertidal. Various sub-environments are recognised: lower and middle intertidal sandflat (lithofacies B and C), high intertidal mudflat to possibly impersistent sabkha (lithofacies E) and sand bars in tidal flat channels (lithofacies A). This interpretation supports the importance of the Röt marine transgression in the Waterstones and suggests general regression into the overlying Keuper Marls.