The Quarterly Journal of the Geological Society of London, Volumen 104

albite anticline apatite appear Ashdown Pebble Bed Atrypa Ayrshire basal Brady calcite Carboniferous Cefn Coed cent chlorite clay coal Coalfield Cretaceous crystals d'Orbigny depth detrital direction dolerite dolerite masses domes dykes Earland east elongated evidence facies feet folding Foraminifera garnet Geol geological girdle gneiss grains granite gravity Green Beds horizon Hyphoplites igneous indicated inlier intrusions Jurassic kilometres kyanite laccolith lava layers Lias limestone lineation Llandrindod Llanfawr lower magma margin metamorphic rocks migmatites minerals monchiquite movement north-east occur Ordovician original outcrop parallel Permian plane plutonic porcellaneous probably Pulur quarry quartz quartz-dolerite regional reticularis Rivière samples schists seams sedimentary sediments shales shear sillimanite sills slump southern species specimens staurolite strata stratigraphical structure surface syncline tectonic temperature Tertiary teschenite thickness thixotropic thrust Top Ashdown Pebble upper valve variation vertical volatile content volcanic Wadhurst yards zircon zone