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Chalk
Chalk is a soft, white, porous, sedimentary carbonate rock. It is a form of limestone composed of the mineral calcite and originally formed deep under the sea by the compression of microscopic plankton that had settled to the sea floor. Chalk is common throughout Western Europe, where deposits underlie parts of France, and steep cliffs are often seen where they meet the sea in places such as the Dover cliffs on the Kent coast of the English Channel. Chalk is mined for use in industry, such as for quicklime, bricks and builder's putty, and in agriculture, for raising pH in soils with high acidity. It is also used for " blackboard chalk" for writing and drawing on various types of surfaces, although these can also be manufactured from other carbonate-based minerals, or gypsum. Description Chalk is a fine-textured, earthy type of limestone distinguished by its light colour, softness, and high porosity. It is composed mostly of tiny fragments of the calcite shells or sk ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blackboard
A blackboard or a chalkboard is a reusable writing surface on which text or drawings are made with sticks of calcium sulphate or calcium carbonate, better known as chalk. Blackboards were originally made of smooth, thin sheets of black or dark grey slate stone. Design A blackboard can simply be a board painted with a dark matte (surface), matte paint (usually black, occasionally dark green). Matte black plastic sign material (known as closed-cell PVC foamboard) is also used to create custom chalkboard art. Blackboards on an A-frame are used by restaurants and bars to advertise daily specials. Adhesive chalkboard surface is also available in stores as rolls of textured black plastic shelf covering, which is applied to the desired wall, door or other surface. A more modern variation consists of a coiled sheet of plastic drawn across two parallel rollers, which can be scrolled to create additional writing space while saving what has been written. The highest grade blackboards ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Southern England Chalk Formation
Downland, chalkland, chalk downs or just downs are areas of open chalk hills, such as the North Downs. This term is used to describe the characteristic landscape in southern England where chalk is exposed at the surface. The name "downs" is derived from the Celtic word "dun", meaning "fort" or " fastness" (and by extension "fortified settlement", from which it entered English as "town", similar to Germanic "burg"/ "burough"), though the original meaning would have been "hill", as early forts were commonly hillforts - compare Germanic "burg" (fort) and "berg" (mountain). Distribution The largest area of downland in southern England is formed by Salisbury Plain, mainly in Wiltshire. To the southwest, downlands continue via Cranborne Chase into Dorset as the Dorset Downs and southwards through Hampshire as the Hampshire Downs onto the Isle of Wight. To the northeast, downlands continue along the Berkshire Downs and Chiltern Hills through parts of Berkshire, Oxfordshire, Buckin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dover Cliffs
The White Cliffs of Dover are the region of English coastline facing the Strait of Dover and France. The cliff face, which reaches a height of , owes its striking appearance to its composition of chalk accented by streaks of black flint, deposited during the Late Cretaceous. The cliffs, on both sides of the town of Dover in Kent, stretch for . The White Cliffs of Dover form part of the North Downs. A section of coastline encompassing the cliffs was purchased by the National Trust in 2016. The cliffs are part of the Dover to Kingsdown Cliffs Site of Special Scientific Interest and Special Area of Conservation. The point where Great Britain is closest to continental Europe, on a clear day the cliffs are visible from France, approximately away. A celebrated UK landmark, the cliffs have featured on commemorative postage stamps issued by the Royal Mail, including in their British coastline series in 2002 and UK A-Z series in 2012. Location The cliffs are part of the coastl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Limestone
Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science), crystal forms of calcium carbonate . Limestone forms when these minerals Precipitation (chemistry), 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 (rock), dolomite, a closely related rock, which contains a high percentage of the mineral Dolomite (mine ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beachy Head
Beachy Head is a Chalk Group, chalk headland in East Sussex, England. It is situated close to Eastbourne, East Sussex, Eastbourne, immediately east of the Seven Sisters, Sussex, Seven Sisters. Beachy Head is located within the administrative area of Eastbourne Borough Council which owns the land, forming part of the Eastbourne Downland Estate. The cliff is the highest chalk sea cliff in Britain, rising to above sea level. The peak allows views of the south east coast towards Dungeness (headland), Dungeness in the east, and to the Isle of Wight in the west. LB&SCR H2 class 4-4-2 (locomotive), 4-4-2 steam locomotive number 424 (later B424, 2424, and 32424) was named ''Beachy Head'' after this landmark. Geology The chalk was formed in the Late Cretaceous epoch, between 66 and 100 million years ago, when the area was under the sea. During the Cenozoic Era, the chalk was tectonic uplift, uplifted (see Geology of England#Cenozoic era, Cenozoic Era). When the Last Glacial Period, las ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coccolithophore
Coccolithophores, or coccolithophorids, are single-celled organisms which are part of the phytoplankton, the autotrophic (self-feeding) component of the plankton community. They form a group of about 200 species, and belong either to the kingdom Protista, according to Robert Whittaker (ecologist), Robert Whittaker's five-kingdom system, or clade Hacrobia, according to a newer biological classification system. Within the Hacrobia, the coccolithophores are in the phylum or division (botany), division Haptophyta, class Prymnesiophyceae (or Coccolithophyceae). Coccolithophores are almost exclusively Marine (ocean), marine, are photosynthesis, photosynthetic and mixotrophic, and exist in large numbers throughout the Photic zone, sunlight zone of the ocean. Coccolithophores are the most productive calcifying organisms on the planet, covering themselves with a calcium carbonate shell called a ''coccosphere''. However, the reasons they calcify remain elusive. One key function may be that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Calcium Carbonate
Calcium carbonate is a chemical compound with the chemical formula . It is a common substance found in Rock (geology), rocks as the minerals calcite and aragonite, most notably in chalk and limestone, eggshells, gastropod shells, shellfish skeletons and pearls. Materials containing much calcium carbonate or resembling it are described as calcareous. Calcium carbonate is the active ingredient in agricultural lime and is produced when calcium ions in hard water react with carbonate ions to form limescale. It has medical use as a calcium supplement or as an antacid, but excessive consumption can be hazardous and cause hypercalcemia and digestive issues. Chemistry Calcium carbonate shares the typical properties of other carbonates. Notably, it: *reacts with acids, releasing carbonic acid which quickly disintegrates into carbon dioxide and water: : *releases carbon dioxide upon heating, called a thermal decomposition reaction, or calcination (to above 840 °C in the case of ), t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kent
Kent is a Ceremonial counties of England, ceremonial county in South East England. It is bordered by Essex across the Thames Estuary to the north, the Strait of Dover to the south-east, East Sussex to the south-west, Surrey to the west, and Greater London to the north-west. The county town is Maidstone. The county has an area of and had population of 1,875,893 in 2022, making it the Ceremonial counties of England#Lieutenancy areas since 1997, fifth most populous county in England. The north of the county contains a conurbation which includes the towns of Chatham, Kent, Chatham, Gillingham, Kent, Gillingham, and Rochester, Kent, Rochester. Other large towns are Maidstone and Ashford, Kent, Ashford, and the City of Canterbury, borough of Canterbury holds City status in the United Kingdom, city status. For local government purposes Kent consists of a non-metropolitan county, with twelve districts, and the unitary authority area of Medway. The county historically included south-ea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nitzana Chalk Curves (2), Western Negev, Israel
Nitzana () may refer to: *Nessana, a city of the ancient Nabataeans located in the Negev desert in Israel *Nitzana, Israel, a communal settlement near the ruins of the Nabataean city *Nitzana Border Crossing, a border crossing between Israel and Egypt See also *Ashdod Nitzanim Sand Dune Park *Nitzan, a communal settlement in southern Israel located among the Nitzanim sand dunes north of Ashkelon *Nitzanei Sinai, a communal settlement also known as Kadesh Barne'a after the Exodus station of that name. {{disambig, geo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gypsum
Gypsum is a soft sulfate mineral composed of calcium sulfate Hydrate, dihydrate, with the chemical formula . It is widely mined and is used as a fertilizer and as the main constituent in many forms of plaster, drywall and blackboard or sidewalk chalk. Gypsum also Crystallization, crystallizes as translucent crystals of selenite (mineral), selenite. It forms as an evaporite mineral and as a Mineral hydration, hydration product of anhydrite. The Mohs scale of mineral hardness defines gypsum as hardness value 2 based on Scratch hardness, scratch hardness comparison. Fine-grained white or lightly tinted forms of gypsum known as alabaster have been used for sculpture by many cultures including Ancient Egypt, Mesopotamia, Ancient Rome, the Byzantine Empire, and the Nottingham alabasters of Medieval England. Etymology and history The word ''wikt:gypsum, gypsum'' is derived from the Greek language, Greek word (), "plaster". Because the quarry, quarries of the Montmartre district of P ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Foraminifera
Foraminifera ( ; Latin for "hole bearers"; informally called "forams") are unicellular organism, single-celled organisms, members of a phylum or class (biology), class of Rhizarian protists characterized by streaming granular Ectoplasm (cell biology), ectoplasm for catching food and other uses; and commonly an external shell (called a "Test (biology), test") of diverse forms and materials. Tests of chitin (found in some simple genera, and ''Textularia'' in particular) are believed to be the most primitive type. Most foraminifera are marine, the majority of which live on or within the seafloor sediment (i.e., are benthos, benthic, with different sized species playing a role within the macrobenthos, meiobenthos, and Benthos, microbenthos), while a smaller number float in the water column at various depths (i.e., are planktonic), which belong to the suborder Globigerinina. Fewer are known from freshwater or brackish conditions, and some very few (nonaquatic) soil species have been id ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seale Chalk Pit 02
Seale may refer to: *Seale, Alabama, an unincorporated community in the United States *Seale, Surrey, a village in England * Seale Hayne College, military hospital in Ivybridge, Devon, UK Seale is also a surname: * Seale Baronets (since 1838), noble family * Charles Seale-Hayne (1833–1903), British member of Parliament from 1885 to 1903 *Alvin Seale (1871–1958), American ichthyologist * Arthur Seale (born 1946), convicted murderer *Bobby Seale (born 1937), American civil rights activist * Clive Seale (born 1955), British medical sociologist * Douglas Seale (1913–1999), British actor * James Ford Seale (1936–2011), Ku Klux Klan member * John Seale (born 1942), Australian cinematographer * Patrick Seale (1930–2014), British journalist * Shonte Seale (born 1999), Barbadian netball player See also * Seal (other) * Seals (other) Seals may refer to: * Pinniped, a diverse group of semi-aquatic marine mammals, many of which are commonly called seals, particula ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
