Arkley, S. L. B., Browne, M. A. E., Albornoz-Parra, L. J. and Barron, H. F. 2011. East Dumbartonshire Geodiversity Audit. British Geological Survey Open Report, OR/09/19. 265pp.
Glossary
| Glossary | |
| Agglomerate | A coarse-grained rock made up of material ejected during a volcanic eruption. |
| Allochthonous | Pertaining to materials, particularly rock masses, that formed somewhere other than their present location, and were transported by fault movements, large-scale gravity sliding, or similar processes. Autochthonous material, in contrast, formed in its present location. Landslides can result in large masses of allochthonous rock, which typically can be distinguished from autochthonous rocks on the basis of their difference in composition. Faults and folds can also separate allochthons from autochthons. |
| Alluvial | Environments, actions and products of rivers or streams. |
| Amygdale | Vesicles and cavities in lavas which are infilled with minerals. |
| Anticline | A structural term describing an arch-shaped fold in rock in which the rock layers are upwardly convex. The oldest rock layers form the core of the fold, and outward from the core progressively younger rocks occur. |
| Basalt | A fine-grained, dark-coloured igneous rock composed of iron and magnesium rich minerals. |
| Bedding | A feature of sedimentary rocks, in which planar or near-planar surfaces known as bedding planes indicate successive depositional surfaces formed as the sediments were laid down. |
| Bedrock | A term used to describe unweathered rock below soil or superficial deposits. Can also be exposed at the surface. |
| Biological weathering | Biological processes and changes that contribute to the breakdown of rocks, for example tree roots or animal burrows. |
| Bioturbation | The disruption of depositional sedimentary structures by organisms e.g. activities such as burrowing. |
| Bivalve | Class of molluscs with paired oval or elongated shell valves joined by a hinge (e.g. mussels). |
| Brachiopods | A phylum of solitary marine shelled invertebrates, the shell is made up of two unequal valves. |
| Braided river | A river consisting of a number of small channels separated by bars |
| Bryozoa | Tiny colonial animals superficially similar to coral. They date back to the |
| Ordovician, 480 million years ago, to present day. Mainly living in a marine environment, they cover rocky surfaces like moss. | |
| Calcite | Calcium Carbonate [CaCO3 a widely distributed mineral and a common constituent of sedimentary rocks, limestone in particular. Also occurs as stalactites and stalagmites and is often the primary constituent of marine shells. |
| Calcareous | Containing calcium carbonate. |
| Calcrete | Conglomerate consisting of surficial sand and gravel cemented into a hard mass by calcium carbonate precipitated from solution and redeposited through the agency of infiltrating waters, or deposited by the escape of carbon dioxide from vadose water. |
| Caledonides | The mountain belt formed during the Caledonian Orogeny |
| Caledonian | Refers to a major mountain-building (orogeny) event related to the closure of the Iapetus Ocean and the convergence of the Laurentia, Baltica and Avalonia crustal blocks during the Ordovician, Silurian and early Devonian. It affected eastern North America, Scotland, Ireland, Scotland, Scandinavia and Greenland. |
| Carboniferous | A geological period [359-299 Ma] of the Palaeozoic Era preceded by the Devonian and followed by the Permian. |
| Cementstone | A name used to describe a limestone, usually containing clays, that is, or was, used to make cement. |
| Chronostratigraphy | The branch of stratigraphy linked to the concept of time. Chronostratigraphical units are defined as bodies of rock that formed during a specific interval of geologic time. Chronostratigraphical units are thus special rock bodies that are conceptual, as well as being material. |
| Clast | Particle of broken down rock, eroded and deposited in a new setting. |
| Columnar jointing | A type of jointing which looks like columns. Found in igneous rocks and results from the internal contraction during cooling of lava, as seen in the vertical columns of the Giant's Causeway, N. Ireland. |
| Conglomerate | A coarse-grained elastic sedimentary rock, a significant proportion of which is composed of rounded or subrounded pebbles and boulders. |
| Coprolite | Fossilised excreta |
| Country rock | A general term used to describe any rock which has been penetrated by an igneous intrusion. |
| Crinoid | A sea dwelling creature (class Crinodea) which has survived since Ordovician times. They are known as sea-lilies and have three sections, the stem, the calyx and feather-like arms by which they collect food. There abundance in the Palaeozoic era has meant that their remains have formed large thicknesses of limestone due to their calcareous skeletons. |
| Cross-bedding | Sets of strata which are inclined to the general stratification of the beds. They dip in the direction of fluid flow at the time when the beds were laid down. |
| Desiccation cracks | Polygonal cracks formed in a sediment as it dries out in a terrestrial environment, also known as shrinkage cracks |
| Devensian | The last glacial stage in Britain, lasting from around 70 000 BP (Before Present) to about 10,000 BP. |
| Devonian | A geological period [416-359 Ma] of the Palaeozoic Era preceded by the Silurian and followed by the Carboniferous. |
| Dolomitic limestone | A limestone containing a high concentration of the mineral dolomite |
| Drumlin | A low, rounded hill of glacial till, which was moulded by glaciers passing over it. Drumlins are elongate in the direction of ice flow. |
| Dyke | A sheet-like body of intrusive igneous rock emplaced along a vertical or near vertical fracture, normally discordant to the structure in the country rocks.. |
| Earth heritage | The geological and landscape heritage of an area. Used mostly in the context of geoconservation. |
| Earth science | Science related to planet Earth. Also known as geoscience. Includes disciplines such as economic geology, geochemistry, geomagnetism, geomorphology, geophysics, glaciology, hydrogeology, mineralogy, palaeontology, petroleum geology, petrology, stratigraphy, structural geology, engineering geology, sedimentology, seismology. |
| Echinoid | Sea urchins (class Echinoidea) are found in oceans all over the world. Their shell or "test", is globular in shape and covered with spines. The size of an adult test is typically from 3 to 10 cm. The earliest known echinoids are found in the rock of the late part of the Ordovician period, and they have survived to the present day. |
| Essexite | A variety of gabbro, an igneous rock, notable for its prominent augite phenocrysts. |
| Eustatic | World-wide changes in sea-level caused either by tectonic movement or growth or melting of glacial ice-sheets (glacioeustatic). |
| Extrusive | Describes igneous rocks that have been extruded onto the Earth's surface, rather than being intruded beneath the surface (intrusive). |
| Fault | A fracture in the Earth's crust across which the rocks have been displaced relative to each other. |
| Fault plane | A vertical or dipping surface of a fault. |
| Felsite | A general term used to denote pale-coloured, fine-grained igneous rocks. |
| Fireclay | A fine-grained sedimentary rock. It often contains fossil plant roots, commonly occurring beneath a coal seam. A fossil soil. |
| Fluvial | Referring to a river environment. |
| Fold | A bend in planar structures such as rock strata or bedding planes. |
| Fold axis | A line which lies parallel to the hinge line and marks the intersection of the axial plane with the hinge zone |
| Formation | The fundamental unit used in lithostratigraphy. Specific features distinguish one formation from another. Formations may be subdivided into members and several formations may constitute a group. |
| Freestone | Any fine-grained sandstone or limestone that can be sawn easily. |
| Gastropod | Molluscs belonging to the class Gastropoda, usually with coiled shells. |
| Geomorphology | The study of landforms and the processes that forms them |
| Glaciofluvial | Refers to sediments deposited by flowing glacial meltwater. |
| Glaciolacustrine | Refers to deposits and landforms derived from materials brought by glacial meltwaters into lake environments. |
| Glaciotectonic | Refers to structures (normally folds and faults) in subglacial and proglacial sediment and bedrock disrupted by ice flow. |
| Hercynian | A period of mountain building (orogeny) in Europe throughout the late Palaeozoic, synonymous with the Variscan Orogeny. |
| Holocene | The youngest epoch of the Quaternary Sub-Era. Covers the last 11 800 years. The concept of the Holocene ending at the end of the 18th Century is gaining ground, with the following Epoch termed the Anthropocene. |
| Igneous rocks | A rock that has formed from the cooling of magma (molten rock). |
| Intrusion | A body of igneous rock which has been injected as magma into existing hard rocks (country-rock). On cooling the magma is called an igneous intrustion. |
| Joints | A fracture, or potential fracture, in a rock adjacent to which there has been no displacement. |
| Lacustrine | Refers to a lake environment. |
| Limestone | Sedimentary rock composed mainly of calcium carbonate. |
| Lithology | The character of a rock expressed in terms of its mineral composition, structure, grain size and arrangement of its constituents. |
| Lithostratigraphy | The branch of stratigraphy concerned with the description of rock units in terms of their lithological features and spatial relationships |
| Ma | Abbreviation for megannum (or more correctly, megannus) meaning million years |
| Magma | Molten rock. |
| Marl | A sedimentary rock, a calcareous (lime-rich) mudstone, or clay-rich chalk. |
| Massive | A term used to describe a thick rock unit without any stratification, jointing or fracturing. |
| Mass-movement | The down slope movement of earth material due to the force of gravity. |
| Meltwater | Water produced by melting of snow or ice. |
| Mountain building | The complex series of geological processes which create mountains. |
| Moraine | Accumulations of material which have been transported and deposited by ice. |
| Orogeny | A period of mountain building by tectonic activity. |
| Ostracod | Small aquatic crustacean dating back to Cambrian times, [class : Ostracoda]. Ostracods vary in size from 0.2mm to 30mm and have a bivalve-like protective shell. They are very important in correlating palaeoenvironments due to their worldwide occurrence. |
| Palaeogene | The lowest period belonging to the Cenozoic Era [65.5-23 Ma]. |
| Paleocene | The lowest epoch of the Palaeogene period, [65.5-55.8 Ma] |
| Palaeozoic | The lowest era of the Phanerozoic Eon. It is preceded by the Proterozoic and is followed by the Mesozoic, [542-251Ma]. |
| Periglacial | Conditions, processes and landforms associated with cold, nonglacial environments. |
| Permian | A geological period [299-251 Ma] of the Palaeozoic Era preceded by the Carboniferous and followed by the Triassic. |
| Phenocryst | Large crystals, usually of near perfect shape, which occur in a finer-grained groundmass in igneous rocks. |
| Pleistocene | A geological epoch [1.8Ma-11.5 ka] preceded by the Pliocene and followed by the Holocene. Part of the Cenozoic Era and Quaternary Sub-Era. |
| Pliocene | A geological epoch [5.3 ? 1.8 Ma] preceded by the Miocene and followed by the |
| Pleistocene. Part of the Cenozoic Era. | |
| Point bar | An accumulation of material (usually sand and/or gravel formed on the inside of a river meander. |
| Porphyritic | The term applied to igneous rocks which contain isolated crystals, or phenocrysts, larger than those forming the main body of the rock. |
| Proterozoic | The Late eon [2500-542 Ma] of the Precambrian followed by the Achaean. |
| Pyroclastic | Describes rocks that form directly by explosive ejection from a volcano. |
| Quartz | The mineral form of silicon dioxide (Si02). The most abundant and widespread of all minerals, it generally appears transparent or white and is hard enough to scratch glass. |
| Quartz- microgabbro | Medium grained basic igneous rock containing minor quartz. |
| Quaternary | A geological sub-era [1.8 Ma to present day] of the Cenozoic Era, following the Neogene |
| River-cliff | A steep face in rock or unconsolidated deposits, located on the outside bend of a meander. Formed by continual undercutting of the face. |
| Ripple marks | Small scale ridges and troughs formed by the flow of water or wind over unconsolidated sandy or silty sediment. The fossilised equivalent of ripples found today on beaches and river sands. |
| Seat earth | A sedimentary rock underlying a coal seam representing an old soil that supported the vegetation from which the coal has formed. |
| Sedimentary rock | A rock formed in one of three main ways: by the deposition of the weathered remains of other rocks (clastic sedimentary rock); by the deposition of the results of biogenic activity; and by precipitation from solution. Four basic processes are involved in the formation of a clastic sedimentary rock: weathering (erosion), transportation, deposition and compaction. |
| Silcrete | A conglomerate consisting of surficial sand and gravel which has been cemented into a hard mass by silica. |
| Sill | A tabular igneous intrusion with concordant contacts with the surrounding country rocks |
| Slickenslides | A polished rock surface, usually displaying linear grooves and ridges. Found on fault planes and caused by the movement of adjacent blocks of rock. |
| Solifluction | Solifluction is a slow downslope flow of water-saturated fragmental material or soil. It is promoted by the existence of permafrost which traps snow and ice melt within the surface layer making it more fluid. |
| Spheroidal weathering | A type of chemical weathering where jointed blocks of rock are slowly rounded by the removal of their outer shells. Often known as onion-skin weathering and typically seen in igneous rocks. |
| Strata | Rocks that form layers or beds. |
| Stratigraphy | The definition and description of the stratified rocks of the Earth's crust. |
| Syncline | A structural term describing a basin- or trough-shaped fold in rock in which rock layers are downwardly concave. The youngest rock layers form the core of the fold and outward from the core progressively older rocks occur. |
| Terrane | A fault-bounded body of rock of regional extent, characterized by a geological history different from that of contiguous terranes. A terrane is generally considered to be a discrete allochthonous fragment of oceanic or continental material added to a craton at an active margin by accretion. |
| Terrigenous | Derived from the erosion of rocks on land. |
| Throw | The amount of displacement on a fault. |
| Thrust | The movement of one crustal surface over another. |
| Tufa | A porous or cellular deposit of calcium carbonate deposited from lime-rich water. |
| Tuff | A rock formed of consolidated volcanic ash and fine-grained material ejected during a volcanic eruption. Finer grained than agglomerate. |
| Unconformable | A term generally applied to younger strata that do not conform in position or that do not have the same dip and strike as those of the immediately underlying rocks. Also applies to the contact between unconformable rocks. |
| Unconformity | A surface of contact between two groups of unconformable strata. Represents a break in the geological record where a combination of erosion and lack of deposition was taking place. |
| Vein | A fracture in the rock infilled with secondary minerals, often quartz or calcite. |
| Vesicles | Small spherical or elliptical cavities in an igneous rock which represent bubbles of gas which existed in the hot magma. Before the gas could escape, the magma cooled and hardened, 'trapping' the gas bubbles in the rock. |