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Portland Admiralty Roach
Portland Admiralty Roach is a kind of stone from the Isle of Portland used to construct " The Cobb", the well-known seawall at Lyme Regis in Dorset. The stone is rich in fossils (known as shells to local masons) often consisting of almost fifty percent fossilized remains with an average size of approximately 35 mm. The stone, which was quarried by Albion Stone, has a maximum bed height of 2 metres. The stone is renowned for being highly frost resistant and being able to withstand the chemical effects of seawater. The stone is an open textured oolitic limestone from the Portlandian formation formed during the Tithonian age, (152.1 ± 4 Ma to 145.0 ± 4 Ma (million years ago)) of the Late Jurassic epoch. It is formed from ooliths in a micrite (fine grained calcium carbonate) matrix. There are many voids in the stone, caused by percolating rainwater dissolving all or parts of its many shell fossils, mainly bivalves and gastropods. See also *List of stone *List of types of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tithonian
In the geological timescale, the Tithonian is the latest age of the Late Jurassic Epoch and the uppermost stage of the Upper Jurassic Series. It spans the time between 152.1 ± 4 Ma and 145.0 ± 4 Ma (million years ago). It is preceded by the Kimmeridgian and followed by the Berriasian (part of the Cretaceous).See for a detailed version of the geologic timescale Gradstein ''et al.'' (2004) Stratigraphic definitions The Tithonian was introduced in scientific literature by German stratigrapher Albert Oppel in 1865. The name Tithonian is unusual in geological stage names because it is derived from Greek mythology. Tithonus was the son of Laomedon of Troy and fell in love with Eos, the Greek goddess of dawn. His name was chosen by Albert Oppel for this stratigraphical stage because the Tithonian finds itself hand in hand with the dawn of the Cretaceous. The base of the Tithonian stage is at the base of the ammonite biozone of '' Hybonoticeras hybonotum''. A global reference profi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Limestone
Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms when these minerals precipitate out of water containing dissolved calcium. This can take place through both biological and nonbiological processes, though biological processes, such as the accumulation of corals and shells in the sea, have likely been more important for the last 540 million years. Limestone often contains fossils which provide scientists with information on ancient environments and on the evolution of life. About 20% to 25% of sedimentary rock is carbonate rock, and most of this is limestone. The remaining carbonate rock is mostly dolomite, a closely related rock, which contains a high percentage of the mineral dolomite, . ''Magnesian limestone'' is an obsolete and poorly-defined term used variously for dolomite, for limes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Types Of Limestone
This is a list of types of limestone arranged according to location. It includes both formal stratigraphic unit names and less formal designations. Africa Egypt *Tura limestone, used for the Great Pyramid casing stones *Mokattam limestone; Great Pyramid core stones and head of the Great Sphinx are of the "Member III" stratum * Galala marble (a type of limestone, not a true marble) Asia India * * Israel (West Bank) * * Europe Austria * Belgium *, (not a "true marble"; Devonian limestone) * * Croatia * France * *, or "Paris stone" (city buildings are widely faced with it) **, or Oise, limestone (variety of Lutetian) * *, in the Loire Valley Germany * * Gibraltar * Ireland * , not a "true marble"; fossiliferous Carboniferous limestone. Italy * , not a "true marble"; fossiliferous limestone United Kingdom England: * (not a "true marble"; Carboniferous limestone) * * * , the famous London Stone is made of this. * (not a "true slate"; thin-bedded limestone ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Stone
This is a geographical list of natural stone used for decorative purposes in construction and monumental sculpture produced in various countries. The dimension-stone industry classifies stone based on appearance and hardness as either "granite", "marble" or "slate". The granite of the dimension-stone industry along with truly granitic rock also includes gneiss, gabbro, anorthosite and even some sedimentary rocks. Natural stone is used as architectural stone (construction, flooring, cladding, counter tops, curbing, etc.) and as raw block and monument stone for the funerary trade. Natural stone is also used in custom stone engraving. The engraved stone can be either decorative or functional. Natural memorial stones are used as natural burial markers. Africa Marble Asia India :See Stones of India Pakistan Pakistan has more than 300 kinds of marble and natural stone. Iran Iran has more than 250 kinds of marble, travertine, onyx, granite, and limestone. Europe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gastropods
The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, from freshwater, and from land. There are many thousands of species of sea snails and slugs, as well as freshwater snails, freshwater limpets, and land snails and slugs. The class Gastropoda contains a vast total of named species, second only to the insects in overall number. The fossil history of this class goes back to the Late Cambrian. , 721 families of gastropods are known, of which 245 are extinct and appear only in the fossil record, while 476 are currently extant with or without a fossil record. Gastropoda (previously known as univalves and sometimes spelled "Gasteropoda") are a major part of the phylum Mollusca, and are the most highly diversified class in the phylum, with 65,000 to 80,000 living snail and slug species. The anatomy, behavior, feeding, and reproduc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bivalves
Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, bivalves have no head and they lack some usual molluscan organs, like the radula and the odontophore. They include the clams, oysters, cockles, mussels, scallops, and numerous other families that live in saltwater, as well as a number of families that live in freshwater. The majority are filter feeders. The gills have evolved into ctenidia, specialised organs for feeding and breathing. Most bivalves bury themselves in sediment, where they are relatively safe from predation. Others lie on the sea floor or attach themselves to rocks or other hard surfaces. Some bivalves, such as the scallops and file shells, can swim. The shipworms bore into wood, clay, or stone and live inside these substances. The shell of a bivalve is composed of calc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Micrite
Micrite is a limestone constituent formed of calcareous particles ranging in diameter up to four μm formed by the recrystallization of lime mud. Flügel, Erik, ''Microfacies of Carbonate Rocks: Analysis, Interpretation and Application,'' Springer, pp 74-94, 2004 The term was coined in 1959 by Robert Folk for his carbonate rock classification system. Micrite is derived from MICRocrystalline calcITE. In the Folk classification micrite is a carbonate rock dominated by fine-grained calcite. Carbonate rocks that contain fine-grained calcite in addition to allochems are named ''intramicrite'', ''oomicrite'', ''biomicrite'' or ''pelmicrite'' under the Folk classification depending on the dominant allochem. Micrite is lime mud, carbonate of mud grade. Micrite as a component of carbonate rocks can occur as a matrix, as micrite envelopes around allochems or as peloids Peloids are allochems that are composed of micrite, irrespective of size, shape, or origin. The two primary types of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oolith
Ooids are small (commonly ≤2 mm in diameter), spheroidal, "coated" (layered) sedimentary grains, usually composed of calcium carbonate, but sometimes made up of iron- or phosphate-based minerals. Ooids usually form on the sea floor, most commonly in shallow tropical seas (around the Bahamas, for example, or in the Persian Gulf). After being buried under additional sediment, these ooid grains can be cemented together to form a sedimentary rock called an ''oolite''. Oolites usually consist of calcium carbonate; these belong to the limestone rock family. Pisoids are similar to ooids, but are larger than 2 mm in diameter, often considerably larger, as with the pisoids in the hot springs at Carlsbad (Karlovy Vary) in the Czech Republic. Formation An ooid forms as a series of concentric layers around a nucleus. The layers contain crystals arranged radially, tangentially or randomly. The nucleus can be a shell fragment, quartz grain or any other small fragment. Most mode ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jurassic
The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The Jurassic constitutes the middle period of the Mesozoic, Mesozoic Era and is named after the Jura Mountains, where limestone strata from the period were first identified. The start of the Jurassic was marked by the major Triassic–Jurassic extinction event, associated with the eruption of the Central Atlantic magmatic province, Central Atlantic Magmatic Province. The beginning of the Toarcian Stage started around 183 million years ago and is marked by an extinction event associated with widespread Anoxic event, oceanic anoxia, ocean acidification, and elevated temperatures likely caused by the eruption of the Karoo-Ferrar, Karoo-Ferrar large igneous provinces. The end of the Jurassic, however, has no clear boundary with the Cretaceous and i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Portland Group (geology)
The Portland Group (defining the Portlandian) is a Late Jurassic (Tithonian) lithostratigraphy, lithostratigraphic group (stratigraphy), group (a sequence of rock strata) in South East England. The name is derived from the Isle of Portland in Dorset where the stratum, strata are exposed and have been extensively worked. Rocks of this age have in the past been called the Portlandian stage (stratigraphy), stage by geologists, which corresponds with the late Tithonian stage of the internationally used geological timescale. Outcrops The Portland Group crops out in Dorset on the Isle of Portland, on and near the south coast of the Isle of Purbeck and to the north of Weymouth, Dorset, Weymouth. Lithology and stratigraphy The rocks include limestones, Dolomite (mineral), dolomitic sandstone, siltstone, and mudstone. It is divided into two formations, the Portland Stone Formation (or 'Portland Limestone Formation') and the underlying Portland Sandstone Formation (or 'Portland Sand ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rock (geology)
In geology, rock (or stone) is any naturally occurring solid mass or aggregate of minerals or mineraloid matter. It is categorized by the minerals included, its chemical composition, and the way in which it is formed. Rocks form the Earth's outer solid layer, the crust, and most of its interior, except for the liquid outer core and pockets of magma in the asthenosphere. The study of rocks involves multiple subdisciplines of geology, including petrology and mineralogy. It may be limited to rocks found on Earth, or it may include planetary geology that studies the rocks of other celestial objects. Rocks are usually grouped into three main groups: igneous rocks, sedimentary rocks and metamorphic rocks. Igneous rocks are formed when magma cools in the Earth's crust, or lava cools on the ground surface or the seabed. Sedimentary rocks are formed by diagenesis and lithification of sediments, which in turn are formed by the weathering, transport, and deposition of existing ro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
