The Santonian is an age in the geologic timescale or a chronostratigraphic stage. It is a subdivision of Upper Cretaceous series, it spans the time between 83.6 ± 0.7 mya. The Santonian is followed by the Campanian; the Santonian stage was established by French geologist Henri Coquand in 1857. It is named after the city of Saintes in the region of Saintonge, where the original type locality is located; the base of the Santonian stage is defined by the appearance of the inoceramid bivalve Cladoceramus undulatoplicatus. Its top is marked by the extinction of the crinoid Marsupites testudinarius. In 2009, a GSSP for both base and top had not yet been appointed; the Santonian is sometimes subdivided into Lower and Upper substages. In the Tethys domain the Santonian is coeval with a single ammonite biozone: that of Placenticeras polyopsis. Biostratigraphy based on inoceramids, nanoplankton or forams is more detailed. Magnoliopsida Advanced dicotyledons Droseraceae: †Palaeoaldrovanda Gradstein, F. M.. G. & Smith, A.
G.. GeoWhen Database - Santonian Late Cretaceous timescale, at the website of the subcommission for stratigraphic information of the ICS Stratigraphic chart of the Late Cretaceous, at the website of Norges Network of offshore records of geology and stratigraphy
Bostrychoceras is a genus of heteromorph ammonite from the family Nostoceratidae. Fossils have been found in Late Cretaceous sediments in North America; the shell of Bostrychoceras begins as a wound helical spire, like that of Nostoceras, from which hangs a U or J shaped body chamber, at least in the adult. The shell is covered with dense, but un-flaired, ribs that are sinuous and oblique. May nor may not have strong constrictions. Cretaceous of Nigeria, South Africa and the United States Notes BibliographyArkell, W. J.. W.. Mesozoic Ammonoidea. Treatise on Invertebrate Paleontology, Part L, Mollusca 4. Lawrence, Kansas: Geological Society of America and University of Kansas Press. Ammonoid Paleobiology by Neil H. Landman, Kazushige Tanabe, Richard Arnold Davis
Sedimentary rocks are types of rock that are formed by the accumulation or deposition of small particules and subsequent cementation of mineral or organic particles on the floor of oceans or other bodies of water at the Earth's surface. Sedimentation is the collective name for processes; the particles that form a sedimentary rock are called sediment, may be composed of geological detritus or biological detritus. Before being deposited, the geological detritus was formed by weathering and erosion from the source area, transported to the place of deposition by water, ice, mass movement or glaciers, which are called agents of denudation. Biological detritus was formed by bodies and parts of dead aquatic organisms, as well as their fecal mass, suspended in water and piling up on the floor of water bodies. Sedimentation may occur as dissolved minerals precipitate from water solution; the sedimentary rock cover of the continents of the Earth's crust is extensive, but the total contribution of sedimentary rocks is estimated to be only 8% of the total volume of the crust.
Sedimentary rocks are only a thin veneer over a crust consisting of igneous and metamorphic rocks. Sedimentary rocks are deposited in layers as strata; the study of sedimentary rocks and rock strata provides information about the subsurface, useful for civil engineering, for example in the construction of roads, tunnels, canals or other structures. Sedimentary rocks are important sources of natural resources like coal, fossil fuels, drinking water or ores; the study of the sequence of sedimentary rock strata is the main source for an understanding of the Earth's history, including palaeogeography and the history of life. The scientific discipline that studies the properties and origin of sedimentary rocks is called sedimentology. Sedimentology is part of both geology and physical geography and overlaps with other disciplines in the Earth sciences, such as pedology, geomorphology and structural geology. Sedimentary rocks have been found on Mars. Sedimentary rocks can be subdivided into four groups based on the processes responsible for their formation: clastic sedimentary rocks, biochemical sedimentary rocks, chemical sedimentary rocks, a fourth category for "other" sedimentary rocks formed by impacts and other minor processes.
Clastic sedimentary rocks are composed of other rock fragments that were cemented by silicate minerals. Clastic rocks are composed of quartz, rock fragments, clay minerals, mica. Clastic sedimentary rocks, are subdivided according to the dominant particle size. Most geologists use the Udden-Wentworth grain size scale and divide unconsolidated sediment into three fractions: gravel and mud; the classification of clastic sedimentary rocks parallels this scheme. This tripartite subdivision is mirrored by the broad categories of rudites and lutites in older literature; the subdivision of these three broad categories is based on differences in clast shape, grain size or texture. Conglomerates are dominantly composed of rounded gravel, while breccias are composed of dominantly angular gravel. Sandstone classification schemes vary but most geologists have adopted the Dott scheme, which uses the relative abundance of quartz and lithic framework grains and the abundance of a muddy matrix between the larger grains.
Composition of framework grains The relative abundance of sand-sized framework grains determines the first word in a sandstone name. Naming depends on the dominance of the three most abundant components quartz, feldspar, or the lithic fragments that originated from other rocks. All other minerals are considered accessories and not used in the naming of the rock, regardless of abundance. Quartz sandstones have >90% quartz grains Feldspathic sandstones have <90% quartz grains and more feldspar grains than lithic grains Lithic sandstones have <90% quartz grains and more lithic grains than feldspar grainsAbundance of muddy matrix material between sand grains When sand-sized particles are deposited, the space between the grains either remains open or is filled with mud. "Clean" sandstones with open pore space are called arenites. Muddy sandstones with abundant muddy matrix are called wackes. Six sandstone names are possible using the descriptors for grain composition and the amount of matrix. For example, a quartz arenite would be composed of quartz grains and have little or no clayey matrix between the grains, a lithic wacke would have abundant lithic grains and abundant muddy matrix, etc.
Although the Dott classification scheme is used by sedimentologists, common names like greywacke and quartz sandstone are still used by non-specialists and in popular literature. Mudrocks are sedimentary rocks composed of at least 50% silt- and clay-sized particles; these fine-grained particles are transported by turbulent flow in water or air, deposited as the flow calms and the particles settle out of suspension. Most authors presently
The Aptian is an age in the geologic timescale or a stage in the stratigraphic column. It is a subdivision of the Early or Lower Cretaceous epoch or series and encompasses the time from 125.0 ± 1.0 Ma to 113.0 ± 1.0 Ma, approximately. The Aptian precedes the Albian, all part of the Lower/Early Cretaceous; the Aptian overlaps the upper part of the regionally used stage Urgonian. The Selli Event known as OAE1a, was one of two oceanic Anoxic events in the Cretaceous period, which occurred around 120 Ma and lasted 1 to 1.3 million years. The Aptian extinction was a minor extinction event hypothesized to have occurred around 116 to 117 Ma; the Aptian was named after the small city of Apt in the Provence region of France, known for its crystallized fruits. The original type locality is in the vicinity of Apt; the Aptian was introduced in scientific literature by French palaeontologist Alcide d'Orbigny in 1840. The base of the Aptian stage is laid at magnetic anomaly M0r. A global reference profile for the base had in 2009 not yet been appointed.
The top of the Aptian is at the first appearance of coccolithophore species Praediscosphaera columnata in the stratigraphic record. In the Tethys domain, the Aptian contains eight ammonite biozones: zone of Hypacanthoplites jacobi zone of Nolaniceras nolani zone of Parahoplites melchioris zone of Epicheloniceras subnodosocostatum zone of Duffrenoyia furcata zone of Deshayesites deshayesi zone of Deshayesites weissi zone of Deshayesites oglanlensisSometimes the Aptian is subdivided in three substages or subages: Bedoulian and Clansayesian. Examples of rock units formed during the Aptian are: Antlers Formation, Cedar Mountain Formation, Cloverly Formation, Elrhaz Formation, Jiufotang Formation, Little Atherfield, Mazong Shan, Potomac Formation, Santana Formation, Twin Mountains Formation, Xinminbao Group and Yixian Formation. Eogaudryceras Georgioceras Lithancylus Pictetia Salfeldiella Zuercherella Lower Ammonitoceras Australiceras Cheloniceras Cicatrites Colombiceras Dufrenoya Eotetragonites Helicancylus Melchiorites Parahoplites Procheloniceras Prodeshayesites Pseudosaynella Roloboceras Shastoceras Upper Acanthohoplites Acanthoplites Ammonoceratites Argonauticeras Beudanticeras Burckhardites Cloioceras Desmoceras Diadochoceras Diodochoceras Eodouvilleiceras Epancyloceras Epicheloniceras Gabbioceras Gargasiceras Gyaloceras Hamites Hulenites Hypacanthoplites Jauberticeras Kazanskyella Knemiceras Mathoceras Mathoceratites Megatyloceras Metahamites Miyakoceras Neosilesites Nodosohoplites Nolaniceras Protacanthoplites Protanisoceras Sinzovia Somalites Tetragonites Theganoceras Trochleiceras Tropaeum Uhligella Conoteuthis Vectibelus Lower Parahibolites Peratobelus Tetrabelus Carinonautilus Heminautilus Upper Zhuralevia Upper Euphylloceras Upper Adygeya Naefia Boluochia zhengi Changchengornis hengdaoziensis Chaoyangia beishanensis Confuciusornis sanctus Cuspirostrisornis houi Jeholornis prima Jixiangornis orientalis Largirostrornis sexdentoris Longchengornis sanyanensis Longipteryx chaoyangensis Sapeornis chaoyangensis Sinornis santensis/Cathayornis yandica Songlingornis linghensis Yanornis martini Yixianornis grabaui Sarcosuchus Hybodus Jinanichthys longicephalus Lycoptera davidi Lycoptera muroii Peipiaosteus pani Protosephurus liui Sinamia zdanskyi Amblydectes Anhanguera Araripedactylus dehmi Araripesaurus castilhoi Arthurdactylus conandoylei Boreopterus cuiae Brasileodactylus araripensis Cearadactylus atrox Chaoyangopterus zhangi Dsungaripterus weii Dsungaripterus brancai Eoazhdarcho liaoxiensis Eopteranodon lii Gegepterus changi Haopterus gracilis Hongshanopterus lacustris Huaxiapterus benxiensis Huaxiapterus corollatus Huaxiapterus jii Istiodactylus latidens Istiodactylus sinensis Jidapterus edentus Liaoningopterus gui Liaoxipterus brachyognathus Lonchodectes Longchengpterus zhaoi Ludodactylus sibbicki Nemicolopterus crypticus Nurhachius ignaciobritoi Ornithocheirus simus Ornithocheirus mesembrinus Pricesaurus megalodon Santanadactylus Sinopterus dongi Sinopterus gui Tapejara navigans Tapejara wellnhoferi Thalassodromeus sethi Tropeognathus mesembrinus Tropeognathus robustus Tupandactylus imperator Aptian extinction Gradstein, F.
M.. G. & Smith, A. G.. D'Orbigny, A. C. V. M.. GeoWhen Database - Aptian Mid-Cretaceous timescale, at the website of the subcommission for stratigraphic information of the ICS Stratigraphic charts of the Lower Cretaceous: and, at the website of Norges Network of offshore records of geology and stratigraphy
Champagne is a commune in the Charente-Maritime department in southwestern France. The Campanian Age of the Cretaceous Period of geological time is named for the commune of Champagne Communes of the Charente-Maritime department INSEE