Què opinen els usuaris - Escriviu una ressenya
No hem trobat cap ressenya als llocs habituals.
Altres edicions - Mostra-ho tot
abundant alluded Ammonites ancient argillaceous basalt beds belong bones brachiopoda calcareous called Cambrian carbonate Carboniferous clay coal coal-measures common conglomerate consist containing corals Crag Cretaceous crystalline denudation deposits Devonian dikes England Eocene eruptions Europe extinct fauna feet thick feldspar fish fissures formations fossil fossiliferous fragments fresh-water genera genus Geol geological geologists gneiss granite horizontal hornblende lakes land lava layers Lias lime limestone Llandeilo Lower Miocene mammalia marine shells marl mass metamorphic mica miles Miocene mollusca mountain Neocomian newer North observed occur Old Red Sandstone older Oolite organic remains origin pebbles period Permian plants Pliocene portion Post-pliocene Professor Purbeck quadrupeds quartz region reptiles rivers sand schists sediment sedimentary seen shale siliceous Silurian slate sometimes species stone strata stratified supposed surface tertiary tion trachyte trees Trias tuffs Upper Miocene valley veins vertical volcanic rocks white chalk
Pàgina 48 - The upper valve is almost invariably wanting, though occasionally found in a perfect state of preservation in the white chalk at some distance. In this case, we see clearly that the sea-urchin first lived from youth to age, then died and lost its spines, which were carried away. Then the young Crania adhered to the bared shell, grew and perished in its turn ; after which, the upper valve was separated from the lower, before the Echinus became enveloped in chalky mud.