Difference between revisions of "Jersey: description of 1:25 000 Channel Islands Sheet 2"
|[checked revision]||[checked revision]|
|Line 682:||Line 682:|
| | An exceptionally coarse-grained igneous rock. Most pegmatites are granitic and form irregular dykes, lenses or veins, especially near margins of intrusions.
| | An exceptionally coarse-grained igneous rock. Most pegmatites are granitic and form irregular dykes, lenses or veins, especially near margins of intrusions.
| | Pericline (doubly plunging fold)
| | Pericline (doubly plunging fold)
Revision as of 19:46, 13 November 2019
|From: Bishop. A. C. and Bisson. G.1989. Jersey: description of 1:25 000 Channel Islands Sheet 2. Classical areas of British geology, London: HMSO for British Geological Survey. © Crown copyright 1989.|
Jersey - description of 1:25 000 Channel Islands Sheet 2
Authors and contributors
- A. C. Bishop. BSc. PHD Department of Mineralogy, British Museum (Natural History), Cromwell Road, London SW7.
- G. Bisson, BSc, ARSM Little Newcombes, Newton St Cyres, Exeter, Devon EX5 5AW
- J. C. Brides, MA, PhD Natural Environment Research Council Polaris House, North Star Avenue, Swindon, Wilts SN2 1 ET
- R. A. Clark, BSc, PhD Department of Earth Sciences, University of Leeds, Leeds LS2 417
- D. G. Helm, BSc, PhD Department of Earth Sciences, Goldsmiths' College, University of London, Rachel McMillan Building, Creek Road, London SE8 .3BU
- = D. H. Keen, BSc, PhD Department of Geography, Coventry (Lanchester) Polytechnic, Priory Street, Coventry CV1 5FB =
- G. J. Lees, BSc Department of Geology, University of Keele, Keele, Staffordshire ST5 5BG
- A. E. Mourant, MA, DPhil, DM, FRCP, FRS The Dower House, Maison de Haut, Longueville, St Saviour, Jersey, Channel Islands
- J. T. Renouf, Bsc., PhD Maison Petit Port, St Brelade, ,Jersey, Channel Islands
- C. M. Thomas, BSc, PhD Esso Norge, PO Box 60, N4033 Forus, Norway
ADAMS, C. J. D. 1967. A geochronological and related isotopic study of rocks from north-western France and the Channel Islands (United Kingdom). Unpublished D.Phil. thesis, University of Oxford.
ADAMS, C. J. D. 1976. Geochronology of the Channel Islands and adjacent French mainland. J. Geol. Soc. London, Vol. 132, 233–250.
ALLEN, P. 1972. Wealden detrital tourmaline: implications for northwestern Europe. Q. J. Geol. Soc. London, Vol. 128, 273–294.
ANGUS, N. S. 1962. Ocellar hybrids from the Tyrone Igneous Series, Ireland. Geol. Mag., Vol. 99, 9–26.
ANSTED, D. T. and LATHAM, R. H. 1862. Geology of the Channel Islands. 247–297 in The Channel Islands. (London: W. H. Allen & Co.)
BACON, M. 1975. A gravity survey of the English Channel between Lyme Regis and St Brieuc Bay. Philos. Trans. R. Soc. London, A279, 69–78.
BARROIS, C. 1895. Le calcaire de Saint-Thurial (Ille-et-Vilaine). An. Soc. Geol. N., Vol. 23, 38–46.
BIRNIE, J. F., JONES, R. L., KEEN, D. H., and WATON, P. V. In preparation. Flandrian vegetational history and sea level change in Jersey, Channel Islands.
BISHOP, A. C. 1964a. The petrogenesis of hornblende-micalamprophyre dykes at South Hill, Jersey, C.I. Geol. Mag., Vol. 101, 302–313.
BISHOP, A. C. 1964b. The La Collette sill, St Helier, Jersey, C.I. Annu. Bull. Soc. Jersiaise, Vol. 18, 418–428.
BISHOP, A. C. and KEY, C. H. 1983. Nature and origin of layering in the diorites of SE Jersey, Channel Islands. J. Geol. Soc. London, Vol. 140, 921–937.
BISHOP, A. C. and MOURANT, A. E. 1979. Discussion on the Rb-Sr whole rock age determination of the Jersey Andesite Formation, Jersey, C.I. J. Geol. Soc. London, Vol. 136, 121–122.
BISHOP, A. C. ROACH, R. A. and ADAMS, C. J. D. 1975. Precambrian rocks within the Hercynides. In A correlation of the Precambrian rocks of the British Isles. HARRIS, A. L. and others. Spec. Rep. Geol. Soc. London, No. 6, 102–107.
BLAND, A. M. 1984. Field relationships within, the South-west Jersey Granite Complex. Proc., Ussher Soc., Vol. 6, 54–59.
BLAND, B. H. 1984. Arumberia Glaessner & Walter, a review of its potential for correlation in the region of the Precambrian-Cambrian boundary. Geol. Mag., Vol. 121, Part 6, 625–633.
BLAND, B. H., EVANS, G., GOLDRING, R., MOURANT, A. E., RENOUF, J. T. and SQUIRE, A. D. 1987. Supposed Precambrian trace fossils from Jersey, Channel Islands. Geol. Mag., Vol. 124, 173.
BOUMA, A. H. 1962. Sedimentology of some flysch deposits; a graphic approach to facies interpretation. (Amsterdam: Elsevier.)
BRIDEN, J. C., CLARK, R. A. and FAIRHEAD, J. D. 1982. Gravity and magnetic studies in the Channel Islands. J. Geol. Soc. London, Vol. 139, 35–48.
CALVEZ, J.-Y. 1976. Comportement des systèmes uranium-plomb et rubidium-strontium dans les orthogneiss d'Icart et de Moelan (Massif Armoricain). These Docteur en Troisieme cycle, Universite de Rennes.
CASIMIR, M. 1934. Studies in folding of the Jersey Shales. Proc. Geol. Assoc., Vol. 45, 162–166.
CASIMIR, M. and HENSON, F. A. 1955. The volcanic and associated rocks of Giffard Bay, Jersey, Channel Islands. Proc. Geol. Assoc., Vol. 60, 30–50.
CHAPPELL, B. W. and WHITE, A. J. R. 1974. Two contrasting granite types. Par. Geol., Vol. 8, 173–174.
COBBING, B. W. and PITCHER, W. S. 1972. The coastal batholith of central Peru. J. Geol. Soc. London, Vol. 128, 421–460.
COGNÉ, J. 1959. Donnees nouvelles sur l'Antécambrien dans l'Ouest de la France. Pentévrien et Briovérien en baie de SaintBrieuc (Cotes-du-Nord). Bull. Soc. Geol. Fr., Vol. 7, part 1: 112–118.
COOPE, G. R., JONES, R. L. and KEEN, D. H. 1980. The palaeoecology and age of peat at Fliquet Bay, Jersey, Channel Islands. J. Biogeogr., Vol. 7, 187–195.
COOPE, G. R., JONES, R. L., KEEN, D. H. and WATON, P. V. 1985. The flora and fauna of late Pleistocene deposits in St Aubin's Bay, Jersey, Channel Islands. Proc. Geol. Assoc., Vol. 96, 315–321.
CORDELL, L. 1970. Iterative three-dimensional solution of gravity anomaly data. USGS computer contribution program number W9303. Washington.
CORNES, H. W. 1933. The age and origin of the Jersey conglomerate. Bull. A nnu. Soc. Jersiaise, Vol. 12, 118–151.
DAVIES, K. H. 1983. Amino acid analysis of Pleistocene marine Mollusca from the Gower Peninsula. Nature, London, Vol. 302, 137–139.
DAVIES, K. H. and KEEN, D. H. 1985. The age of Pleistocene marine deposits at Portland, Dorset. Proc. Geol. Assoc., Vol. 96, 217 –225.
DAY, A. A. 1955. On the values of gravity at St Anne (Alderney), St Peter Port (Guernsey), and St Helier (Jersey). Mon. Not. R. Astron. Soc. Geophys. Suppl., Vol. 7, 76–79.
DAY, A. A. 1959. Gravity anomalies in the Channel Islands. Geol. Mag., Vo1,96, 89–98.
DEWEY, J. F. 1969. Evolution of the Appalachian/Caledonian orogen. Nature, London, Phys. Sci., Vol. 22, 124–129.
DUFF, B. A. 1978. Rb-Sr whole-rock age determination of the Jersey Andesite Formation, Jersey, C.I. J. Geol. Soc. London, Vol. 135, 153–156.
DUFF, B. A. 1979. The palaeomagnetism of Cambro-Ordovician red beds, the Erquy Spilite Series and the Trégastel-Ploumanac'h granite complex, Armorican Massif (France and the Channel Islands). Geophys. J. R. Astron. Soc., Vol. 59, 345–365.
DUFF, B. A. 1980. The palaeomagnetism of Jersey volcanics and dykes, and the Lower Palaeozoic apparent polar wander path for Europe. Geophys. J. R. Astron. Soc., Vol. 60, 355–375.
DUFF, B. A. 1981. Scattered palaeomagnetic directions acquired during dioritization and stoping of the diorite-metagabbro complex, Jersey, C.I. J. Geol. Soc. London, Vol. 138, 485–492.
DUMARESQ, P. 1935 (1685). A survey of ye Island of Jersey. Bull. Annu. Soc. Jersiaise, Vol. 12, 415–416.
DUNLOP, A. 1911. On the Pleistocene beds of Jersey. Bull. Annu. Soc. Jersiaise, Vol. 7, 112–120.
FURNIVAL, W. J. 1904. Jersey chinastone. 320–323 in Leadless decorative tiles, faience and mosaic. (Stone, Staffordshire.)
GINNS, M. 1973. Grouville Common during the German occupation. Bull. Annu. Soc. Jersiaise, Vol. 21, 195–199.
GRAINDOR, M. J. 1957. Le Brioverien dans le nord-est du massif armoricain. Mem. Expl. Carte Geol. Fr. 211pp.
GROVES, A. W. 1927. The heavy minerals of the plutonic rocks of the Channel Islands. I (Jersey). Geol. Mag., Vol. 64, 241–251.
GROVES, A. W. 1930. The heavy mineral suites and correlation of the granites of northern Brittany, the Channel Islands and the Cotentin. Geol. Mag., Vol. 67, 218–240.
HAWKES, J. 1938. The archaeology of the Channel Islands, Vol.II, Jersey. (Jersey: Societe Jersiaise.)
HELM, D. G. 1983. The structure and tectonic evolution of the Jersey Shale Formation, St Ouen's Bay, Jersey, Channel Islands. Proc. Geol. Assoc., Vol. 94, 201–216.
HELM, D. G. 1984. The tectonic evolution of Jersey, Channel Islands. Proc. Geol. Assoc., Vol. 95, 1–15.
HELM, D. G. and PICKERING, K. T. 1985. The Jersey Shale Formation-a late Precambrian deep-water siliciclastic system, Jersey, Channel Islands. Sediment. Geol., Vol. 43, 43–66.
HENSON, F. A. 1956. The geology of south-west Jersey, Channel Islands. Proc. Geol. Assoc., Vol. 67, 266–295.
INSTITUTE OF GEOLOGICAL SCIENCES. 1979. Bouguer gravity anomaly map, 1:250 000 Series (Revised edition), Guernsey Sheet 49N 04W.
IXER, R. A. 1980. The ore minerals of Jersey. Annu. Bull. Soc. Jersiaise, Vol. 22, 443–451.
IXER, R. A. and STANLEY, C. J. 1980. Mineralization at Le Pulec, Jersey, Channel Islands. Mineral. Mag., Vol. 43, 1025–1029.
KEEN, D. H. 1975. Two aspects of the last interglacial in Jersey. Annu. Bull. Soc. Jersiaise, Vol. 21, 392–396.
KEEN, D. H. 1978a. A Palaeolithic flint flake from Noirmont Point. Annu. Ball. Soc. Jersiaise, Vol. 22, 205–208.
KEEN, D. H. 1978b. The Pleistocene deposits of the Channel Islands. Rep. Inst. Geol. Sci., No. 78/26.
KEEN, D. H. 1981. The Holocene deposits of the Channel Islands. Rep. Inst. Geol. Sci., No. 81/10.
KEEN, D. H. 1982. Late Pleistocene land Mollusca in the Channel Islands. J. Conchol., Vol. 31, 57–61.
KEEN, D. H., HARMON, R. S. and ANDREWS, J. T. 1981. U-series and amino-acid dates from Jersey. Nature, London, Vol. 289, 162 -164.
KEY, C. H. 1974. The layered diorites of Jersey, Channel Islands. Unpublished PhD thesis, University of London.
KEY, C. H. 1977. Origin of appinitic pockets in the diorites of Jersey, Channel Islands. Mineral. Mag., Vol. 41, 183–192.
LAUTRIDOU, J.-P. 1973. Les loess du Riss dans le bassin de Ia Seine. Proceedings of the IXth INQUA Congress, Christchurch, NZ, 54–55.
LAUTRIDOU, J. -P. (editor). 1982. The Quaternary of Normandy. Field handbook of the QRA meeting in Normandy, May 1982. (Cambridge: Quaternary Research Association.)
LEES, G. J. 1982. Mica-lamprophyres of south-western England. 301–302 in Igneous rocks of the British Isles SUTHERLAND, D. S. (editor). (Chichester: Wiley.)
LEFORT, J. P. 1975. Etude géologique du socle antémésozoIque au nord du massif Armoricain; limites et structures de la Domnonee. Philos. Trans. R. Soc. Lond., A279, 123–135.
LEUTWEIN, F. 1968. Contribution a Ia connaissance du Précambrien récent en Europe Occidentale et développement geochronologique du Briovérien en Bretagne (France). Can. J. Earth Sci., Vol. 5, 673–682.
LEUTWEIN, F. and SONET, J. 1965. Contribution à la connaissance de l'évolution géochronologique de la partie nord-est du massif Armoricain francais. Sci. Terre, Nancy, Vol. 10, 345–367.
MASSON SMITH, D., HOWELL, P. M. and ABERNETHY-CLARK, A. B. D. E. 1974. The National Gravity Reference Network 1973. (Southampton: Ordnance Survey.)
MITCHELL, A. H. and READING, H. G. 1971. Evolution of island arcs. j Geol., Vol. 79, 283–284.
MOURANT, A. E. 1932. The spherulitic rhyolites of Jersey. Mineral. Mag., Vol. 23, 227-'238.
MOURANT, A. E. 1933. The geology of eastern Jersey. Q. J. Geol. Soc. London, Vol. 89, 273–307.
MOURANT, A. E. 1935. The Pleistocene deposits of Jersey. Annu. Bull. Soc. Jersiaise, Vol. 12, 489–496.
MOURANT, A. E. 1940. In ROBINSON, A. J. Report of the Geological Section, 1939. Bull. Annu. Soc. Jersiaise, Vol. 14, 13–15.
MOURANT, A. E. 1956. The use of Ecréhous stone in Jersey. Bull. Annu. Soc. Jersiaise, Vol. 16, 373–376.
MOURANT, A. E. 1961. The minerals of Jersey. Annu. Bull. Soc. Jersiaise, Vol. 18, 69–90.
MOURANT, A. E. 1977. The use of Fort Regent granite in megalithic monuments in Jersey. Annu. Bull. Soc. Jersiaise, Vol. 22, 41- 49.
MOURANT, A. E. 1978. The minerals of Jersey. (St Helier, Jersey: Société Jersiaise.)
MOURANT, A. E. and WARREN, J. P. 1934. Minerals and mining in the Channel Islands. Rep. Trans. Soc. Guernesiaise, Vol. 12 (for 1933), 73–88.
MUTTI, E. and RICCI LUCCHI, F. 1972. Le Torbitit dell'Apennino settenrionale; introduzione all'analisi di facies. Mem. Soc. Geol. Ital., Vol. 11, 161–199.
NORMARK, W. R. 1978. Fan valleys, channels and depositional lobes on modern submarine fans: characters for recognition of sandy turbidite environments. Bull. Am. Assoc. Pet. Geol., Vol. 62, 912–931.
NOURY, CH. 1886. Geologie de ferny. (Paris: F. Savy; Jersey: Le Feuvre.)
OGLER, E. F. 1871. Rapport sur les mines de plomb du Pulec. (Jersey.) 1–8.
OLIVER, R. L. 1958. Andradite from the island of Jersey. Annu. Bull. Soc. Jersiaise, Vol. 17, 181–184.
PICKERING, K. T. 1981. Two types of outer fan lobe sequence, from the late Precambrian Kongsfjord Formation submarine fan, Finnmark, North Norway. J. Sediment. Petrol., Vol. 51, 1277 -1286.
PICKERING, K. T. 1983. Transitional submarine fan deposits from the late Precambrian Kongsfjord Formation submarine fan, NE Finnmark. N Norway. Sedimentology, Vol. 30, 181–199.
PLEES, W. 1817. An account of the island ofJersey. (Southampton.)
PLYMEN, G. H. 1921. The geology of Jersey. Proc. Geol. Assoc., Vol. 32, 151–172.
RANWELI., D. S. 1975. The dunes of St Ouen's Bay, Jersey: an ecological survey, part I. History and plant communities least modified by human influence. Annu. Bull. Soc. Jersiaise, Vol. 21, 381–391.
RANWELI., D. S. 1976. The dunes of St Ouen's Bay, Jersey: an ecological survey, part H. Plant communities strongly modified by man, the whole flora and management implications. Annu. Bull. Soc. Jersiaise, Vol. 21, 505–516.
RENOUF, J. T. 1969. Geological report for 1968. Annu. Bull. Soc. Jersiaise, Vol. 20, 15–16.
RENOUF, J. T. 1974. The Proterozoic and Palaeozoic development of the Armorican and Cornubian provinces. Proc. Ussher Soc., Vol. 3, Part 1, 6–43.
RENOUF, J. T. and BISHOP, A. C. 1971. The geology of the Fort Regent road tunnel. Annu. Bull. Soc. Jersiaise, Vol. 20, 275–283.
RICHARDSON, K. 1984. The sedimentology and structure of the Rozel Conglomerate. Unpublished report, Goldsmiths' College, London.
ROACH, R. A., ADAMS, C. J. D., BROWN, M., POWER, G. and RYAN, P. 1972. The Precambrian stratigraphy of the Armorican massif, northwest France. Proc. Mt. Geol. Congr., Sess. 24, Montreal 1972, 246–252.
ROBINSON, A. J. 1960. Geological report for 1959. Annu. Bull. Soc. Jersiaise, Vol. 17, 290–292.
ROSS, C. S. and SMITH, R. L. 1961. Ash flow tuffs-their origin, geologic relations and identification. U.S. Geol. Suro. Paper 366. 81 pp.
RYBOT, N. V. L. 1926. The corbels [of Grosnez Castle, Jersey]. Bull. Annu. Soc. Jersiaise, Vol. 10, 293–296.
RYBOT, N. V. L. 1947. The quarrying and splitting of rocks in Jersey. Bull. Annu. Soc. Jersiaise, Vol. 14, 283–292.
SHACKLETON, N. J. and OPDYKE, N. D. 1973. Oxygen isotope and palaeomagnetic stratigraphy of equatorial Pacific Core V28–238: Oxygen isotope temperatures and ice volumes on a 105 and 106 year scale. Qual. Res., Vol. 3, 39–55.
SHOTTON, F. W. and WILLIAMS, R. E. G. 1971. Birmingham University radiocarbon dates V. Radiocarbon, Vol. 13, Part 2, 141–156.
SMITH, H. G. 1933. Some lamprophyres of the Channel Islands. Proc. Geol. Assoc., Vol. 44, 121–130.
SMITH, H. G. 1936a. The South Hill lamprophyre, Jersey. Geol. Mag., Vol. 73, 87–91.
SMITH, H. G. 1936b. New lamprophyres and monchiquites from Jersey. Q. J. Geol. Soc. London, Vol. 92, 365–383.
SPEIGHT, J. M., SKELHORN, R. R., SLOAN, T. and KNAPP, R. J. 1982. The dyke swarms of Scotland. 449–459 in Igneous rocks of the British Isles. SUTHERLAND, D. S. (editor). (Chichester: Wiley).
SQUIRE, A. D. 1970. The sedimentology, provenance and age of the Rozel Conglomerate, Jersey, Channel Islands. Unpublished report, Chelsea College, London.
SQUIRE, A. D. 1973. Discovery of late Precambrian trace fossils in Jersey, Channel Islands. Geol. Mag., Vol. 110, 223–226.
SQUIRE, A. D. 1974. Brioverian sedimentology and structure of Jersey and adjacent areas. Unpublished PhD thesis, University of London.
STANLEY, C. J. and IxER, R. A. 1982. Mineralization at Le Pulec, Jersey, Channel Islands; No. 1 Lode. Mineral. Mag., Vol. 46, 134–136.
STEVENS, J. 1965. Old Jersey Houses. V ol.I. (Chichester: Phillimore.)
STEVENS, J. 1977. Old Jersey Houses. V ol.II. (Chichester: Phillimore.)
TEILHARD DE CHARDIN, P. 1920. Sur la structure de l'Ile de Jersey. Bull. Soc. Géol. Fr., 4e Série, Vol. 19 (for 1919), 273–278.
THOMAS, G. M. 1977. Volcanic rocks and their minor intrusives, eastern Jersey, Channel Islands. Unpublished PhD thesis, University of London.
THURRELL, R. G. 1972. The sand resources of St Ouen's Bay, Jersey. Unpublished report, Institute of Geological Sciences, London.
WALKER, R. G. 1978. Deep-water sandstone facies and ancient submarine fans: models for exploration for stratigraphic traps. Bull. Am. Assoc. Pet. Geol., Vol. 62, 932–966.
WALKER, R. G. 1984. In Facies models, Second Edition, Geosci. Can. Reprint Ser., Geol. Assoc. Can., No. 1, 317pp. WALKER, R. G. (editor).
WELLS, A. K. and BISHOP, A. C. 1955. An appinitic facies associated with certain granites in Jersey, Channel Islands. Q. J. Geol. Soc. London, Vol. 111, 143–166.
WILLIAMS, B. 1871. Report on the Jersey silver-lead mine. (Jersey)
WILLIAMS, T. D. 1934. Trade relations between Jersey, Guernsey and Welsh ports in Elizabethan times. Bull. Annu. Soc. Jersiaise, Vol. 12, 261–270.
ZEUNER, F. E. 1940. The age of Neanderthal Man, with notes on the Cotte de St Brelade, Jersey, C.I. Occas. Pap. Inst. Archaeol., No. 3.
|Adamellite||Granite in which alkali feldspar and plagioclase occur in about equal amounts.|
|Agglomerate||A volcanic rock formed of pyroclastic blocks or fragments generally more than 64 mm in diameter.|
|Air-fall tuff||A tuff formed by consolidation of fine-grained pyroclastic debris (ash) which was laid down on land from the air.|
|Amphibolite||A metamorphic rock consisting mainly of amphibole and plagioclase.|
|Amygdale||A gas bubble or cavity in an igneous rock which has been filled with secondary minerals.|
|Andesite||A lava of intermediate composition consisting of plagioclase feldspar (usually andesine) and one or more ferromagnesian minerals.|
|Andinotype||An orogeny characterised by sedimentation in fault-margined furrows, andesites, I-type tonalites, burial metamorphism, cauldron batholiths that feed volcanoes, and vertical movement with minimal shortening.|
|Anticline||A fold, generally convex upward (an arch), the core of which contains the older rocks.|
|Aphyric||Adjective applied usually to a fine-grained igneous rock which lacks phenocrysts.|
|Aplite||A light-coloured, fine- to medium-grained acid igneous rock with an equigranular texture and consisting mainly of quartz and feldspar.|
|Aplogranite||A light-coloured, even-grained plutonic acid igneous rock consisting mainly of quartz and alkali feldspar.|
|Apophysis||An offshoot from an igneous intrusion.|
|Appinite||A dark-coloured plutonic igneous rock rich in hornblende which commonly occurs as elongate prismatic crystals.|
|Ash||Unconsolidated fine-grained pyroclastic debris.|
|Assimilation||Incorporation of foreign material into a magma.|
|Aureole||The rocks adjoining an igneous intrusion that have suffered contact metamorphism.|
|Authigenesis||The process whereby minerals are formed in place within a sedimentary rock during or after deposition.|
|Autobreccia||A rock composed of angular fragments, formed by a process that is penecontemporaneous with the deposition or consolidation of the rock.|
|Axial plane||The surface that passes through successive hinge lines within a fold.|
|Axial trace||The line of intersection of the axial plane or axial surface of a fold with the Earth's surface.|
|Axiolite||A spherulitic aggregate elongated along a central axis.|
|Basalt||A fine-grained lava or minor intrusion composed mainly of calcic plagioclase and pyroxene with or without olivine.|
|Base-surge||A cloud of gas and solid debris that moves rapidly outward from the base of a volcanic explosion column.|
|Bouguer anomaly||A gravity anomaly left after corrections have been made for the attraction effect of topography.|
|Braid||To branch and rejoin repeatedly, forming a network.|
|Breccio-conglomerate||A sedimentary rock consisting of angular and rounded sedimentary clasts.|
|Camptonite||A lamprophyre consisting mainly of plagioclase (usually labradorite) and brown hornblende, the hornblende forming elongated prismatic crystals.|
|Cataclasite||A rock formed by shattering less severe than would produce a mylonite.|
|China-stone||Any form of granitic rock used in the manufacture of china and usually, but not necessarily, kaolinised.|
|Clast||A grain or fragment in a sedimentary rock.|
|Cleavage||Aligned and closely spaced tectonic surfaces along which a rock tends to split.|
|Columnar jointing||Prismatic fractures in lavas, sills or dykes that have resulted from cooling.|
|= Concretion =
||= A nodular or irregular mass formed by the secondary precipitation of minerals about a nucleus or centre in a sedimentary rock. =
|Conglomerate||A sedimentary rock consisting of cemented rounded pebbles or clasts.|
|Contact metamorphism||Metamorphism resulting from the emplacement of a body of magma.|
|Cross-cut||A mine tunnel driven through barren rock, commonly to intersect a mineral deposit.|
|Crystal fractionation||The separation of a cooling magma into parts of differing composition by the successive crystallisation and settling of different minerals at progressively lower temperatures.|
|Devitrification||The replacement of glassy texture by crystalline texture in a volcanic rock during or after cooling.|
|Dextral fault||A fault in which the rock on the far side appears to have been moved horizontally to the right.|
|Diagenesis||The sum of the processes involved in changing a sediment into a sedimentary rock.|
|Diorite||A plutonic igneous rock of intermediate composition consisting essentially of plagioclase and hornblende, with or without biotite and pyroxene.|
|Disconformity||A break in the stratigraphic sequence without major structural discordance.|
|Dolerite||A medium-grained igneous rock consisting mainly of calcic plagioclase and pyroxene, commonly with an ophitic texture, with or without olivine.|
|Dolmen||A prehistoric burial chamber.|
|Drag fold||A fold produced by differential movement between beds on the limb of a large fold or by shearing in a fault zone.|
|Dune||A ripple-like bedform greater than 10cm in height and 1 m in wavelength.|
|Enclave||An inclusion or fragment enclosed in an igneous rock.|
|Epiclastic||An adjective applied to sedimentary rock formed of fragments derived by weathering and erosion of older rocks.|
|Epidiorite||A metamorphosed basic igneous rock, consisting principally of amphibole and plagioclase.|
|Eugeosynclinal||A major elongate structural and sedimentological unit of the Earth's crust, with a thick sequence of deep-water sediments and characteristic igneous rocks.|
|Euhedral||An adjective applied to mineral grains in igneous rocks that are bounded by their natural crystal faces.|
|Eutaxitic texture||The texture in tuffs where shards and pumice are flattened to give a banded or streaky appearance.|
|Facies||The lithology, structure, fauna, etc., of a rock unit.|
|Felsite||A fine-grained igneous rock composed mainly of quartz and feldspar. Fiamme Collapsed pumice fragments in ignimbrite, commonly with ragged terminations.|
|Flow banding||A structure characterised by alternating layers of slightly .different composition and texture owing to the movement of magma, most common in silicic lava flows.|
|Fluxion banding||Flow banding.|
|Flysch||A marine sedimentary facies comprising a thick sequence of sandstones, shales and mudstones, typically found on the borders of the Alps.|
|Fold axis or hinge-line||The line at which the two sides or limbs of a fold meet.|
|Gabbro||A coarse-grained intrusive igneous rock composed essentially of basic plagioclase and pyroxene with or without olivine.|
|Gneiss||A foliated metamorphic rock in which layers of coarsely granular minerals alternate with layers or lenticles of platy minerals.|
|Graded bed||A sedimentary unit in which the grains normally show a progression from coarse below to fine above. Some beds display inverse grading.|
|Granite||In common usage, a coarse-grained acid igneous rock consisting essentially of quartz, feldspar and mica. More precisely, the feldspar is predominantly (greater than 2/3) alkali feldspar.|
|Granoblastic||A textural term used of regionally metamorphosed rocks having mineral grains of the same general size.|
|Granophyre||A granitic rock in which the bulk consists of micrographic intergrowths of quartz and potassic feldspar, giving a texture called granophyric.|
|Gravity gradient||A measure of the change in the value of gravity relative to horizontal distance.|
|Greenschist facies||Regionally metamorphosed rocks produced under conditions of low temperature and low to medium pressure.|
|Greywacke||A poorly sorted sandstone with more than 15 per cent interstitial matrix and angular to subangular grains of quartz, feldspar and lithic fragments.|
|Heavy mineral||A mineral with specific gravity greater than 2.9; a mineral that will sink in bromoform.|
|Hornfels||A rock consisting of fine equidimensional grains without preferred orientation, produced by contact metamorphism.|
|Humic||Derived from plants.|
|Hydrothermal||Relating to hot solutions emanating from a magma.|
|Ignimbrite||A subaerial pyroclastic rock formed by the deposition and consolidation of ash flows and glowing avalanches (nuees ardentes).|
|Imbrication||A sloping and overlapping arrangement.|
|Intraclast||A sedimentary rock fragment derived penecontemporaneously from within the sedimentary basin, e.g. pebbles in an intraformational conglomerate.|
|Isochron||A straight line constructed most commonly by plotting the ratio 87Rb/86Sr against the ratio 87Sr/86Sr, or 207Pb/204Pb or 208Pb/204Pb against 206Pb/204Pb, for different rocks or minerals from the same geological body. The slope of the isochron is a function of the age of the body.|
|Isocline||A fold with parallel limbs. Isotopic dating The determination of the age of a rock by methods based on the nuclear decay of certain natural chemical elements contained within it.|
|Kaersutite||A titanium-bearing amphibole.|
|Keratophyre||A soda-rich acid to intermediate lava or minor intrusion.|
|Kersantite||A lamprophyre consisting mainly of biotite and plagioclase, usually accompanied by augite and/or hornblende.|
|Lacustrine||Relating to a lake.|
|Lahar||A mudflow composed of volcaniclastic material.|
|Lamprophyre||A general term for dark, porphyritic intrusive igneous rocks composed of phenocrysts of one or more of dark mica, pyroxene, amphibole or olivine in a groundmass of alkali feldspar or plagioclase. Some lamprophyres are feldspar-free.|
|Lapilli||Fragments in the range of 5 to 50 mm ejected by volcanic eruption.|
|Liquefaction||Quicksand effect in soft sediments owing to sudden increase in pore fluid pressure and loss of cohesion.|
|Lithic||Made of rock.|
|Machair||Low-lying sandy environment.|
|Mafic.||Rich in ferromagnesian minerals|
|Magnetic anomaly||A departure from the normal magnetic field of the Earth.|
|Megacryst||A crystal significantly larger than the grains in the surrounding groundmass of an igneous rock. Metasediment Metamorphosed sedimentary rock.|
|Metasomatism||Metamorphism involving a change in the bulk composition of the affected rock.|
|Microlites, microliths||Microscopic needle-like crystals generally found in volcanic rocks and having some determinable optical properties.|
|Minette||A lamprophyre in which biotite forms phenocrysts and orthoclase is the main feldspar.|
|Molasse||A sequence of sedimentary rocks laid down in intermontane basins.|
|Monchiquite||A lamprophyre composed essentially of phenocrysts of pyroxene, olivine and titanium-bearing amphibole in an isotropic groundmass consisting largely of analcime, commonly highly altered.|
|Monzonite||A coarse-grained igneous rock intermediate in composition between syenite and diorite, containing approximately equal amounts of potassic feldspar and plagioclase.|
|Mortar structure||A structure produced by the mechanical fracture of rocks, especially granites and gneisses, such that the comminuted grains of quartz and feldspar surround larger grains of the same minerals.|
|Mylonite||A compact fine-grained streaked and flinty rock formed by severe granulation and shearing of rocks during dynamic metamorphism.|
|Neomagmatic||An adjective referring to magma formed by partial or complete refusion of pre-existing rocks.|
|Orthogneiss||A coarse-grained rock produced by the regional metamorphism of igneous rocks.|
|Palaeocurrent||A current that flowed in the geological past.|
|Palaeomagnetism||The study of natural remanent magnetisation in order to determine the intensity and direction of the Earth's magnetic field in the geological past.|
|Palaeoslope||A slope that existed in the geological past.|
|Parasitic fold||A relatively small fold on the limb or in the hinge of a larger congruous fold of the same generation.|
|Parataxitic texture||An extreme variation of eutaxitic texture in tuffs, in which the shards and pumice lumps are flattened and appear to have been drawn out.|
|Pegmatite||An exceptionally coarse-grained igneous rock. Most pegmatites are granitic and form irregular dykes, lenses or veins, especially near margins of intrusions.|
|Pericline (doubly plunging fold)||A fold in which the beds dip outwards from the centre (dome) or towards the centre (basin).|
|Perlitic texture||Small-scale arcuate cracks caused by cooling in volcanic glass.|
|Petrographical||Pertaining to the descriptive aspects of the study of rocks (petrology).|
|Phenocryst||A crystal in an igneous rock that is conspicuously larger than those of the matrix in which it is set.|
|Plunge||The inclination of a fold axis. Plutonic Relating to igneous rocks formed at great depth in the Earth. P|
|neumatolysis||Alteration of a rock, or crystallisation of minerals, by gases emanating from a magma.|
|Poikilitic||A texture in which smaller crystals of one mineral are enclosed within a larger crystal of another.|
|Poikiloblastic||A texture in a metamorphic rock formed where a recrystallised mineral surrounds relicts of earlier minerals.|
|Polygenetic||Originating in more than one way.|
|Porphyritic||A texture in which larger crystals in an igneous rock are set in a finer-grained groundmass, as in a porphyry.|
|Porphyroblast||A large, usually well shaped crystal, that has grown in a finer-grained matrix during metamorphism.|
|Pressure solution||The mass transfer of material by fluid diffusion from one part of a rock to another as a result of grainto-grain contact during tectonic deformation.|
|Propylite||A hydrothermally altered andesite or related rock containing secondary minerals such as chlorite, zoisite and calcite.|
|Provenance||Source areas from which fragments in sedimentary rocks have been derived.|
|Proximal||Close to the source of supply of sedimentary material.|
|Pseudomorph||A mineral whose outward crystal form is that of another, which it has replaced.|
|Pumice||A highly vesiculated glassy lava, usually of rhyolite and light enough to float in water.|
|Pyroclastic||Adjective describing a elastic rock formed by explosion or eruption from a volcanic vent.|
|Quartz-wacke||A sedimentary rock with 15 per cent or more matrix in which framework grains are mainly quartz.|
|Radiocarbon date||The age of a deposit determined by measuring the content of carbon-14 ("C) in organic material.|
|Raised beach||A beach deposit left at a level above that of the modern beach, following a lowering of sea level.|
|Rhyolite||A fine-grained acid extrusive igneous rock, commonly porphyritic and flow-banded.|
|Ripple mark||A small sand ridge formed by the movement of water or sediment over unconsolidated sediment. Ripples usually have a cross-laminated internal structure useful in determining the palaeocurrent direction.|
|Schist||A strongly foliated metamorphic rock in which the lamellar or elongate minerals show parallel orientation.|
|Scree||An accumulation of angular rock fragments, usually at the foot of and derived from a cliff or hill.|
|Shard||A glass fragment typically found in pyroclastic rocks, having distinctive cuspate margins.|
|Shear||A fracture caused by shearing due to compressive stress.|
|Sinistral fault||A fault in which the rock on the far side appears to have been moved horizontally to the left.|
|Sole mark||A sedimentary structure at the base of a bed produced by currents and used to determine the direction of palaeocurrent flow.|
|Spessartite||A lamprophyre consisting mainly of phenocrysts of hornblende set in a groundmass of sodic plagioclase.|
|Spherulite||A mass of radiating crystals, usually spherical in shape.|
|Stalagmite||A column of calcareous material deposited on the floor of a cave by water dripping from the roof.|
|Strike slip||The component of the movement on a fault that is parallel to the strike of the fault.|
|Subhedral crystal||A mineral within an igneous rock only partly bounded by its natural crystal faces.|
|Sub-volcanic||Relating to the region below the Earth's surface where dykes and sills are intruded.|
|Supracrustal||Descriptive of rock that overlies the basement.|
|Syenite||A plutonic rock consisting essentially of alkali-feldspars and amphibole or dark mica.|
|Syncline||A fold, generally convex downward, the core of which contains the younger rocks.|
|Synclinorium||A composite regional syncline composed of lesser folds.|
|Synplutonic||A term used to describe a dyke intruded into a granite rock before the granite had solidified.|
|Tear fault||A fault in which the movement has been substantially in a horizontal sense.|
|Tectonic||Relating to the forces involved in the large-scale structural evolution of the upper part of the Earth's crust.|
|Tectonic pitting||The indentation of one sedimentary grain by another.|
|Trace fossil||A sedimentary structure, such as a track or boring, left by an animal in the geological past.|
|Tuff||A lithified deposit of volcanic ash.|
|Tuffite||An admixture of pyroclastic (>25 per cent) and epiclastic (>25 per cent) material.|
|Turbidity current||A turbulent current laden with suspended sediment at the base of a column of water that flowed down a slope under the influence of gravity.|
|Unconformity||A break in the stratigraphical sequence marked by a structural discordance.|
|Vergence||The direction in which a fold is inclined or overturned.|
|Volcaniclastic||Composed mainly of volcanic rock fragments.|
|Wrench fault||A tear fault.|
|Xenocryst||A crystal in an igneous rock to which it is not genetically related.|
|Xenolith||An inclusion in an igneous rock to which it is not genetically related.|