Geological Magazine, Volume 6; Volume 56

abundant Adorals Ammonites Ammonoids anhydrite appear bands beds Brachiopods breccias British calcareous calcite Cambrian Carboniferous cent Chalk character clay coal Coal-measures connexion contain Conulus Corwen Cretaceous crystals deposits described Devonian diabase district dolomitic dorsal Durham earthquake epidiorite evidence fault fauna feet felspar flint formation fossils fragments gabbro genera genus Geol GEOLOGICAL MAGAZINE Geological Survey geologists glacial gneiss grains granite gravels hornblende hornfels igneous rocks intrusion ironstone Journ later Lower magma Magnesian Limestone material Megacystis miles mineral Museum North occur oolitic origin outcrop paper periproct peristome Permian plates posterior potash present probably Pyrina pyroxene quarry quartz reef regarded sand Sandstone schists septa septum shales shell side silica similar siphuncle species specimens strata structure suggested surface Surv suture suture-line thickness tourmaline Trechmann Trilobites tuff Upper valley ventral volcanic Walcott zone