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29-437: (Redirected from RN1 ) Route nationale 1 ( RN 1 or RN1 ) is the name of a trunk road in many counties: Route nationale 1 (France) between Paris and Calais. Route nationale 1 (French Guiana) between Cayenne and Saint-Laurent-du-Maroni Route nationale 1 (Niger) Route nationale 1 (Réunion) Route nationale 1 (Tunisia)  [ fr ] Topics referred to by

58-447: A phosphate mineral) is also sometimes present, as nodules or as small pellets interpreted as fecal pellets. In some chalk beds, the calcite has been converted to dolomite , CaMg(CO 3 ) 2 , and in a few cases the dolomitized chalk has been dedolomitized back to calcite. Chalk is highly porous, with typical values of porosity ranging from 35 to 47 per cent. While it is similar in appearance to both gypsum and diatomite , chalk

87-642: Is mined from chalk deposits both above ground and underground . Chalk mining boomed during the Industrial Revolution , due to the need for chalk products such as quicklime and bricks . Most people first encounter chalk in school where it refers to blackboard chalk , which was originally made of mineral chalk, since it readily crumbles and leaves particles that stick loosely to rough surfaces, allowing it to make writing that can be readily erased. Blackboard chalk manufacturers now may use mineral chalk, other mineral sources of calcium carbonate, or

116-469: 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 . 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 skeletons of plankton , such as foraminifera or coccolithophores . These fragments mostly take

145-428: Is applied to the hands and feet to remove perspiration and reduce slipping. Chalk may also be used as a house construction material instead of brick or wattle and daub : quarried chalk was cut into blocks and used as ashlar , or loose chalk was rammed into blocks and laid in mortar. There are still houses standing which have been constructed using chalk as the main building material. Most are pre- Victorian though

174-518: Is commonly used as a drying agent to obtain better grip by gymnasts and rock climbers. Glazing putty mainly contains chalk as a filler in linseed oil . Chalk and other forms of limestone may be used for their properties as a base . Chalk is a source of quicklime by thermal decomposition , or slaked lime following quenching of quicklime with water. In agriculture , chalk is used for raising pH in soils with high acidity . Small doses of chalk can also be used as an antacid . Additionally,

203-546: Is different from Wikidata All article disambiguation pages All disambiguation pages Route nationale 1 (France) The majority of the original road has been superseded by the A16 autoroute . As a result, much of the road has now been reclassified the RD 1001 , RD 901 and RD 940 . Paris - Saint-Denis - Beauvais - Amiens - Abbeville - Boulogne-sur-Mer - Calais - Dunkerque - Belgium The road begins at

232-515: Is identifiable by its hardness, fossil content, and its reaction to acid (it produces effervescence on contact). In Western Europe, chalk was formed in the Late Cretaceous Epoch and the early Palaeocene Epoch (between 100 and 61 million years ago). It was deposited on extensive continental shelves at depths between 100 and 600 metres (330 and 1,970 ft), during a time of nonseasonal (likely arid) climate that reduced

261-582: Is now usually made of talc (magnesium silicate). Chalk beds form important petroleum reservoirs in the North Sea and along the Gulf Coast of North America. In southeast England, deneholes are a notable example of ancient chalk pits. Such bell pits may also mark the sites of ancient flint mines, where the prime object was to remove flint nodules for stone tool manufacture. The surface remains at Cissbury are one such example, but perhaps

290-503: The A16 autoroute starts, and then crosses the River Oise . The autoroute heads to the west while the N 1 heads out over rolling countryside northwards after Chambly. The road heads through Noailles before the road crosses the autoroute and enters Beauvais . The road passes round the east of Beauvais passing the airport before turning north east. The road heads over the generally flat countryside to Breteuil . It runs parallel to

319-645: The Cretaceous Period was named for these deposits. The name Cretaceous was derived from Latin creta , meaning chalk . Some deposits of chalk were formed after the Cretaceous. The Chalk Group is a European stratigraphic unit deposited during the late Cretaceous Period. It forms the famous White Cliffs of Dover in Kent , England, as well as their counterparts of the Cap Blanc Nez on

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348-588: The Mont d'Hubert (151 m). The road then enters Calais from the west. The town is a major port with ferry services to England. The A26 autoroute starts in the town heading south east to Paris, Lille and Reims . In the year 1973 the RN 1 took over this part from the RN 40. 2006 this part was downgraded from RN to RD. The A16 autoroute passes round the town with the Eurotunnel terminal and heading north to

377-409: The bedding or as nodules in seams , or linings to fractures , embedded in chalk. It is probably derived from sponge spicules or other siliceous organisms as water is expelled upwards during compaction. Flint is often deposited around larger fossils such as Echinoidea which may be silicified (i.e. replaced molecule by molecule by flint). Chalk is so common in Cretaceous marine beds that

406-523: 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

435-704: The A 16 and enters the town of Amiens from the South. The road crosses the River Somme in the town. In Amiens the road turns north west along the Somme valley past the memorial Samara. The road heads out of the steep valley sides before the town of Abbeville . To the west of the town is the A28 autoroute which heads south to Rouen . The N 1 heads north again passing south west of the Forêt de Crécy . The road then crosses

464-585: The Belgium frontier and takes the majority of through traffic. The old RN 1 is now numbered the RD 940 and passes north east parallel to the coast across flat drained farmland. The road reaches the river Aa and the town of Gravelines after 25 km. After the town the road is numbered the RN 1 and it passes a series of refineries and other industrial complexes in the Zone industrielle Portuaire . The road then enters

493-732: The North American interior. Chalk is also found in western Egypt (Khoman Formation) and western Australia ( Miria Formation ). Chalk of Oligocene to Neogene age has been found in drill cores of rock under the Pacific Ocean at Stewart Arch in the Solomon Islands . There are layers of chalk, containing Globorotalia , in the Nicosia Formation of Cyprus , which formed during the Pliocene . Chalk

522-751: The Porte de la Chapelle in Paris and runs below the A1 autoroute as the Boulevard de President Wilson north through the northern Paris suburbs to Saint-Denis . The road heads through Saint Denis as the Avenue Lenine before heading north east. The road then heads to the east of Saint Brice Sous Foret, with the Foret Dominiale de Montmorency . The road heads into the Foret Dominiale de L'Isle-Adam where

551-473: The amount of erosion from nearby exposed rock. The lack of nearby erosion explains the high purity of chalk. The coccolithophores, foraminifera, and other microscopic organisms from which the chalk came mostly form low-magnesium calcite skeletons, so the sediments were already in the form of highly stable low-magnesium calcite when deposited. This is in contrast with most other limestones, which formed from high-magnesium calcite or aragonite that rapidly converted to

580-512: The form of calcite plates ranging from 0.5 to 4 microns in size, though about 10% to 25% of a typical chalk is composed of fragments that are 10 to 100 microns in size. The larger fragments include intact plankton skeletons and skeletal fragments of larger organisms, such as molluscs , echinoderms , or bryozoans . Chalk is typically almost pure calcite, CaCO 3 , with just 2% to 4% of other minerals. These are usually quartz and clay minerals , though collophane (cryptocrystalline apatite ,

609-581: The major port and historic town of Boulogne-sur-Mer . After Boulogne the road has reached the English Channel and the road heads along the coast past the Colonne de la Grande Armée and has now been re-numbered the RD 940. The road heads through Wimereux and close to the Cap Gris-Nez (50 m), Wissant and the Cap Blanc-Nez (134 m), here the road passes a Monument to Latham and past

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638-555: The marshy valley of the river Authie. The countryside becomes a series of chalk downland and deep valleys. The road continues to the valley of the Canche and the historic walled town of Montreuil . The road rises again reaching 134 m above sea level north of the town which offers views over the Parc Naturel Regional caps et Marais D'Opale . The road passes through the village of Samer before turning north west to

667-528: The mineral gypsum ( calcium sulfate ). While gypsum-based blackboard chalk is the lowest cost to produce, and thus widely used in the developing world , use of carbonate-based chalk produces larger particles and thus less dust, and it is marketed as "dustless chalk". Coloured chalks, pastel chalks, and sidewalk chalk (shaped into larger sticks and often coloured), used to draw on sidewalks , streets, and driveways , are primarily made of gypsum rather than calcium carbonate chalk. Magnesium carbonate chalk

696-406: The more stable low-magnesium calcite after deposition, resulting in the early cementation of such limestones. In chalk, absence of this calcium carbonate conversion process prevented early cementation, which partially accounts for chalk's high porosity. Chalk is also the only form of limestone that commonly shows signs of compaction. Flint (a type of chert ) is very common as bands parallel to

725-562: The most famous is the extensive complex at Grimes Graves in Norfolk . Chalk was traditionally used in recreation. In field sports, such as tennis played on grass, powdered chalk was used to mark the boundary lines of the playing field or court. If a ball hits the line, a cloud of chalk or pigment dust will be visible. In recent years, powdered chalk has been replaced with titanium dioxide . In gymnastics, rock-climbing, weightlifting and tug of war , chalk — now usually magnesium carbonate —

754-667: The other side of the Dover Strait . The Champagne region of France is mostly underlain by chalk deposits, which contain artificial caves used for wine storage . Some of the highest chalk cliffs in the world occur at Jasmund National Park in Germany and at Møns Klint in Denmark . Chalk deposits are also found in Cretaceous beds on other continents, such as the Austin Chalk , Selma Group , and Niobrara Formations of

783-499: The port of Dunkerque where the RN 225 (European Route E 42) heads south east to Lille . The RN 1 continues along the coast to the Frontier with Belgium where it continues as the N 39. 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

812-448: The same term [REDACTED] This disambiguation page lists articles associated with the title Route nationale 1 . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=Route_nationale_1_(disambiguation)&oldid=1012997267 " Category : Disambiguation pages Hidden categories: Short description

841-436: The small particles of chalk make it a substance ideal for cleaning and polishing. For example, toothpaste commonly contains small amounts of chalk, which serves as a mild abrasive . Polishing chalk is chalk prepared with a carefully controlled grain size, for very fine polishing of metals. French chalk (also known as tailor's chalk) is traditionally a hard chalk used to make temporary markings on cloth, mainly by tailors . It

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