Facies, origin, and palaeontological inventory of an Early Carboniferous neptunian dyke in the Devonian reef limestone near Rösenbeck (Brilon Anticline, Rhenish Mountains)

The Devonian reef limestone complex of Rösenbeck near Brilon (Rhenish Mountains) shows numerous neptunian dykes and other hollows which have been filled with Carboniferous siliciclastic as well as fossil-rich carbonate sediments with ammonoids, conodonts, and chondrichthyan fish. While the shales of the infill can be interpreted as autochthonous sediments, the carbonates represent erratic blocks of sediments which were deposited in elevated areas but subsequently eroded and transported as erratic blocks into the karstic cavities. The biota of the carbonates demonstrates that two stratigraphic intervals are represented: (1) the Tournaisian–Viséan boundary interval, which can be identified by the presence of trilobites, and (2) the late Viséan (Asbian–Brigantian), proven by the presence of ammonoids and conodonts embedded in shales that probably have an early Serpukhovian age. Two carbonate facies can be distinguished in the Late Viséan blocks: (1) low-energy micritic sediments with Goniatites crenistria, which are probably equivalent to the crenistria Limestone and (2) high-energy (tempestite) sediments with numerous ammonoid specimens and in a more subordinate role other to fossil groups.

The Age of the Neptunian Dyke at Hazler Hill

During the Easter Field Meeting of the Sedgwick Club, portions of the Neptunian dyke at Hazier Hill, near Church Stretton, were collected and brought back to Cambridge for further examination. The material consisted of a buff-coloured, sandy mudstone with scatters of facetted pebbles of quartzite and igneous material, including weathered rhyolite, up to a centimetre in diameter. The material proved to be richly fossiliferous and the following fauna was obtained which, we believe, throws some light on the age of these sand-filled fissures :—

An Excavation revealing the junction between Ingletonian and Coniston Limestone at Ingleton

While conducting elementary field-classes in the Ingleton area it is not possible to show students any convincing grounds for separating the Ingletonian Series from the Coniston Limestone above. The field-evidence which so strongly impressed Hughes, Goodchild, Gunn, and Green, and which apparently convinced Aveline against his will, still exists. In all three streams the highest beds of the Ingletonian are slates, which might be thought to show a gradation into the Coniston Limestone above, and the dip and strike of the Coniston Limestone appear closely similar to that of the near-by Ingletonian. Against these tangible facts arguments based on petrological similarities, even the evidence of the Neptunian dyke, are apt to seem slightly strained. Accordingly, during a field-excursion I suggested that an attempt be made to excavate the actual junction, and during the summer three students of Imperial College, Messrs. R. W. D. Elwell, G. J. H. McCall, and A. F. Trendall, have succeeded in laying it bare. To their enthusiasm and hard work the success of the attempt is wholly due. Owing to the kindness of Mr. W. S. Worthington, of Ingleton, the new exposure will be left open indefinitely.