The Quarterly Journal of the Geological Society of London, Volumen 115

algae anticline appears Arklow axial plane bands black shales breccia Calcareous Group Cambrian Carboniferous Cavetown Chert clay pebble conglomerate crinoidal Culm Measures deposits developed dolerite dykes east Elliott evidence exposures fauna feet thick feldspar folds formation fossils Fremington Geol Geological glacial Goniatites granite granophyre horizon igneous Interglacial intrusion Isingiro joints lavas limestones Lower Boulder-clay Lower Culm Measures Meldon Quarry metasomatism Middle Sand miles movement mudstone Mynydd Moel Nar Valley normal faults normal limb north-east north-west northern occur Ordovician outcrop plunge porphyritic quartz Quartzite Group quartzites reverse fault rhyolitic River sandstone sedimentary sediments Shale and Quartzite shales sill similar slates slaty cleavage south-east south-west steep bedding stratigraphical structures succession suggested surface sutures syncline tectonic terraces thrust trend trilobites tuffs Upper Acid Group Upper Basic Group Upper Boulder-clay Upper Culm Measures Volcanic Group volcanic rocks weathering zone