A glossary of geological terms used on this site
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Geologists are (in)famous for their long words and sometimes impenetrable terminology! This page may help you understand the site better. Where definitions refer you to the Geology Chart, please click HERE. The main Building Stone page will then open in a new window.
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Ashlar: Building stone, rectangular, finely dressed (cut or sawn) with smooth external face and sides for close fitting
Bath Stone: Middle Jurassic limestone widely used in church windows and quoins Bridport and Yeovil Sands: Geological formation extending from Dorset coast to Yeovil. See Geology chart Bartonian: Geological time period. See Geology chart Beer Stone: Local limestone once quarried in SE Devon. See Geology chart Bembridge Limestone: Local limestone once quarried on Isle of Wight. See Geology chart Bembridge Stone: Local limestone once quarried on Isle of Wight. See Geology chart Binstead Stone: Local limestone once quarried on Isle of Wight. See Geology chart Bioclast: Broken fossil shells, components of many limestones Bivalve: Mollusc with two halves to its shell: clams, scallops, oysters, etc . Blue Lias: Basal Jurassic Limestone, thin beds. Quarried in SW Dorset & Somerset. See Geology chart Burr: Local limestone quarried on Isle of Purbeck. See Geology chart Calcarenite: A limestone composed of sand-sized grains of calcium carbonate, usually shell debris. Calcite: Calcium carbonate, defining component of all limestones. Carboniferous: Geological time period. Rocks of this age not exposed in Dorset. Imported limestones used. Chalk: Soft very fine-grained limestone. Geological formation widespread in S & SE England Chert: Very hard rock composed of silica replacing sandstone or limestone in patches. Cenomanian: Geological time period. See Geology chart Chilmark: Area west of Salisbury where Portland Limestones quarried. Clavellata: Species name of fossil bivalve. Geological formation name - See Geology chart Concretions: Hard, dense, ovoid or spherical rock within a softer sedimentary rock layer. Cornbrash: Middle Jurassic shelly oolitic limestone used as building stone. See Geology chart Corallian: Upper Jurassic shelly limestone used as building stone. Geological Group - See Geology chart Cretaceous: Geological time period. See Geology chart Crinoid: Fossil marine animal related to starfish, also known as "Sea Lilies" Current bedded: Sedimentary layers which were deposited inclined rather than horizontal; cross-bedding. Cypris: A genus of ostracod (qv) Dolomite: A mineral or rock largely composed of Calcium Magnesium Carbonate Dressings: Building stones cut to a smooth face for windows, quoins, string courses Echinoid: A Sea Urchin - a type of marine animal living on or within the sea bed Eocene: Geological time period. See Geology chart Featherbed: Very shelly local limestone once quarried on Isle of Wight. See Geology chart Featherstone: Very shelly local limestone once quarried on Isle of Wight. See Geology chart Ferroan: Containing iron minerals usually oxidised to an orange-brown colour; ferruginous Ferruginous: Containing iron minerals usually oxidised to an orange-brown colour; ferroan Flint: Very hard rock composed of silica replacing chalk in patches Forest Marble: Middle Jurassic shelly limestones & sandstones used as building stone. See Geology chart Freestone: Any rock which can be cut in any direction for building use Fuller's Earth: Middle Jurassic clay with some limestones used as building stone. See Geology chart Gastropod: A type of Mollusc, e.g.. Snail, which can live on land, in freshwater or in the sea Glauconite: A green mineral formed from volcanic ash deposited in marine conditions |
Ham Hill Stone: Lower Jurassic coarse-grained bioclastic limestone, orange-brown. See Geology chart
Heathstone: A ferruginous sandstone used as a building stone. See Geology chart Inferior Oolite: Middle Jurassic shelly limestone used as a building stone. See Geology chart Ironstone: A sedimentary rock with a high iron mineral content; ferruginous. See Geology chart Junction Bed: Lower Jurassic dense limestone, cream coloured. See Geology chart Jurassic: Geological time period. See Geology chart Kellaways: Middle Jurassic rock formation. See Geology chart Knapped: Flint or chert which have been split and trimmed for use in building. Laminations: Very thin layers within a sedimentary rock Ledger slabs: Engraved slabs of rock used as gravestones, vertically or horizontally, inside a church Limestone: A sedimentary rock containing more than 50% calcium carbonate Lower Lias: A former division of the Jurassic. See Geology chart Marble: In building use, any rock which can be polished for ornamental use. Not the geological meaning. Marnhull Stone: Upper Jurassic oolitic limestone used as building stone. - See Geology chart Micrite: Microcrystalline calcite (qv) Middle Lias : A former division of the Jurassic. See Geology chart Myophorella: Genus name of fossil bivalve Myophorella clavellata. Clavellata Formation - See Geology chart Napped: Flint or chert which have been split and trimmed for use in building New Vein: Local limestone quarried on Isle of Purbeck. See Geology chart Non-Dorset: Here, sources of building stone imported for use in Dorset Buildings Oolitic/Ooidal: Limestones (oolites) rich in spherical grains of calcium carbonate (ooids) formed in warm shallow seas Osmington Oolite: Upper Jurassic oolitic limestone used as building stone. - See Geology chart Ostracods: Small crustaceans with shell-like bodies (1-5mm) preserved in some building stones Oxford Clay: Upper Jurassic rock Formation. See Geology chart Paleocene: Geological time period. See Geology chart Photomic.: Photomicrograph - photograph of a thin slice of rock viewed in a microscope Plagioclase feldspar: Type of mineral common in sedimentary rocks derived by erosion of granites Poikilitic: A rock texture in which small, randomly orientated, crystals are enclosed within larger crystals Portland Stone: Upper Jurassic limestone. See Geology chart Porosity: The percentage of space between the grains of a sedimentary rock PPL: Plane Polarised Light - Microscopy term Purbeck: Lower Cretaceous "rock Group". Geographical area in East Dorset. See Geology chart Purbeck Marble: Lower Cretaceous gastropodal limestone, polished for decorative purposes. See Geology chart Quarr: Very shelly local limestone once quarried on Isle of Wight. See Geology chart Quartz: Silica mineral common in sedimentary rocks Quoin: Architectural term: Corner stones of buildings Render: Artificial coating applied to buildings Ripple Marks: Minor undulations seen in sedimentary rocks deposited in shallow seas Rubble: Dressed building stone (e.g. by hammer, guillotine) generally used between quoins, windows and ashlar courses Sandstone: Sedimentary rock composed of mineral grains 0.062 to 2mm diameter, often quartz Sarsen Stone: Hard quartzose non-marine sandstone. See Geology chart Sedimentary: Rocks formed by the erosion of other rocks; by accumulation of organic matter; by evaporation of seawater Shale: Sedimentary rock comprising clay which has been compressed by burial such that it splits horizontally Slate: Metamorphic rock: originally clay, altered by pressure & heat such that it splits at an angle to the original Sparite: Sparry calcite - calcium carbonate crystals large enough to be visible by the naked eye Tertiary: Geological time period. See Geology chart Todber Freestone: Upper Jurassic oolitic limestone used as building stone. See Geology chart Trigonia: Genus name of a fossil bivalve Unconformity: The contact where sedimentary rocks overlie older rocks with a time gap and often a different structure Upper Greensand: Mid-Cretaceous glauconitic marine sandstone widely used for building. See Geology chart Upper Lias: A former division of the Jurassic. See Geology chart Veins: Thin mineral sheets, usually calcite, cross-cutting sedimentary rocks. Purbeck rock units - See Geology chart Weald Clay: Lower Cretaceous rock Formation. See Geology chart White Lias: Youngest Triassic limestone, pale, dense. See Geology chart Wight Stone: Very shelly local limestone once quarried on Isle of Wight. See Geology chart XPL: Cross Polarised Light - Microscopy term Yellow Ledge Stone Band: Local stone in Kimmeridge Group. See Geology chart |
