The molluscs compose the large phylum Mollusca of invertebrate animals. Around 85,000 extant species of molluscs are recognized, molluscs are the largest marine phylum, comprising about 23% of all the named marine organisms. Numerous molluscs live in freshwater and terrestrial habitats and they are highly diverse, not just in size and in anatomical structure, but in behaviour and in habitat. The phylum is divided into 9 or 10 taxonomic classes. The gastropods are by far the most numerous molluscs in terms of classified species, the three most universal features defining modern molluscs are a mantle with a significant cavity used for breathing and excretion, the presence of a radula, and the structure of the nervous system. Other than these things, molluscs express great morphological diversity, so many textbooks base their descriptions on an ancestral mollusc. This has a single, limpet-like shell on top, which is made of proteins and chitin reinforced with calcium carbonate, the underside of the animal consists of a single muscular foot.
Although molluscs are coelomates, the coelom tends to be small, the main body cavity is a hemocoel through which blood circulates, their circulatory systems are mainly open. The generalized mollusc has two paired nerve cords, or three in bivalves, the brain, in species that have one, encircles the esophagus. Most molluscs have eyes, and all have sensors to detect chemicals, the simplest type of molluscan reproductive system relies on external fertilization, but more complex variations occur. All produce eggs, from which may emerge trochophore larvae, more complex veliger larvae, good evidence exists for the appearance of gastropods and bivalves in the Cambrian period 541 to 485.4 million years ago. Molluscs have, for centuries, been the source of important luxury goods, notably pearls, mother of pearl, Tyrian purple dye and their shells have been used as money in some preindustrial societies. Mollusc species can represent hazards or pests for human activities, the bite of the blue-ringed octopus is often fatal, and that of Octopus apollyon causes inflammation that can last for over a month.
Stings from a few species of large tropical cone shells can kill, schistosomiasis is transmitted to humans via water snail hosts, and affects about 200 million people. Snails and slugs can be serious pests, and accidental or deliberate introduction of some snail species into new environments has seriously damaged some ecosystems. The words mollusc and mollusk are both derived from the French mollusque, which originated from the Latin molluscus, from mollis, molluscus was itself an adaptation of Aristotles τα μαλακά, the soft things, which he applied to cuttlefish. The scientific study of molluscs is accordingly called malacology, as it is now known these groups have no relation to molluscs, and very little to one another, the name Molluscoida has been abandoned. The most universal features of the structure of molluscs are a mantle with a significant cavity used for breathing and excretion
Wiltshire is a county in South West England with an area of 3,485 km2. It is landlocked and borders the counties of Dorset, the county town was originally Wilton, after which the county is named, but Wiltshire Council is now based in the new county town of Trowbridge. Wiltshire is characterised by its high downland and wide valleys, Salisbury Plain is noted for being the location of the Stonehenge and Avebury stone circles and other ancient landmarks, and as a training area for the British Army. The city of Salisbury is notable for its mediaeval cathedral, important country houses open to the public include Longleat, near Warminster, and the National Trusts Stourhead, near Mere. The county, in the 9th century written as Wiltunscir, Wiltonshire, is named after the county town of Wilton. Wiltshire is notable for its pre-Roman archaeology, the Mesolithic and Bronze Age people that occupied southern Britain built settlements on the hills and downland that cover Wiltshire. Stonehenge and Avebury are perhaps the most famous Neolithic sites in the UK, in the 6th and 7th centuries Wiltshire was at the western edge of Saxon Britain, as Cranborne Chase and the Somerset Levels prevented the advance to the west.
The Battle of Bedwyn was fought in 675 between Escuin, a West Saxon nobleman who had seized the throne of Queen Saxburga, in 878 the Danes invaded the county. Following the Norman Conquest, large areas of the country came into the possession of the crown, at the time of the Domesday Survey the industry of Wiltshire was largely agricultural,390 mills are mentioned, and vineyards at Tollard and Lacock. In the 17th century English Civil War Wiltshire was largely Parliamentarian, the Battle of Roundway Down, a Royalist victory, was fought near Devizes. The Royal Wiltshire Yeomanry currently lives on as Y Squadron, based in Swindon, around 1800 the Kennet and Avon Canal was built through Wiltshire, providing a route for transporting cargoes from Bristol to London until the development of the Great Western Railway. Information on the 261 civil parishes of Wiltshire is available on the Wiltshire Community History website, run by the Libraries and this site includes maps, demographic data and modern pictures and short histories.
The local nickname for Wiltshire natives is moonrakers and this originated from a story of smugglers who managed to foil the local Excise men by hiding their alcohol, possibly French brandy in barrels or kegs, in a village pond. The officials took them for simple yokels or mad and left them alone, many villages claim the tale for their own village pond, but the story is most commonly linked with The Crammer in Devizes. Two-thirds of Wiltshire, a rural county, lies on chalk. This chalk is part of a system of chalk downlands throughout eastern and southern England formed by the rocks of the Chalk Group, the largest area of chalk in Wiltshire is Salisbury Plain, which is used mainly for arable agriculture and by the British Army as training ranges. The highest point in the county is the Tan Hill–Milk Hill ridge in the Pewsey Vale, just to the north of Salisbury Plain, the chalk uplands run northeast into West Berkshire in the Marlborough Downs ridge, and southwest into Dorset as Cranborne Chase.
Cranborne Chase, which straddles the border, like Salisbury Plain, yielded much Stone Age, the Marlborough Downs are part of the North Wessex Downs AONB, a 1,730 km2 conservation area
Beeston Regis is a village and civil parish in the North Norfolk district of Norfolk, England. It is about a mile east of Sheringham and near the coast, the village is 2 miles west of Cromer and 16 miles north of the city of Norwich. According to the 2011 census it had a population of 1,062, the nearest airport is Norwich International Airport. The North Sea is the boundary of the parish. There are few traces of antiquity in Beeston Regis. However, evidence of Roman habitation was found on Beeston Regis Heath in 1859 when a set of quern-stones were found dating from Roman times. Quern-stones were used to grind materials, the most important of which was grain to make flour for bread. On Beeston Regis Heath there are circular pits called Hills and Holes and they are thought to date from prehistoric times. During the Saxon-Norman to Medieval periods these pits were dug to obtain iron ore, Beeston Regis is mentioned in Domesday Book of 1086, where it is called Besetune and Besetuna/tune. The main landholders of the parish were William dEcouis and Hugh de Montfort, the main tenant was Ingulf, The survey lists ½ a mill.
In the Domesday survey fractions were used to indicate that the entry, Beeston Regis was once known as Beeston-next-the-Sea, but from 1399 when Henry Bolingbroke, Earl of Lancaster, became King Henry IV, the name became Beeston Regis. Regis means of the king, and the living and manor of Beeston became part of the Crown, for Main Article Please See, Priory of St Mary in the Meadow, Beeston Regis Beeston Regis has the remains of an Augustinian priory known as Beeston Regis Priory. Founded in 1216, in 1535 it had only a prior and four canons, the boys were in effect the boarders at the canons school, and their number was increased by day boys. The priory had 40 acres of land rights to wrecks. The priory lasted until 1538 when King Henry VIII banned the Catholic religion, the ruins indicate that the church nave was about 75 feet long, having a chancel added. Beeston Priory was independent, unlike many small houses of the Augustinian Order, a tunnel is said to run to the Dunstable Arms Inn from the ruins of the priory, but if it ever existed its whereabouts is a long-forgotten secret.
The suppression of the Priory and its school left no provision for education. This is believed to have led Sir John Gresham to found Greshams School at nearby Holt in 1555, the cloister, to the south of the nave of the priory church, is now part of the Priory Farm garden
The Cenomanian is, in the ICS geological timescale the oldest or earliest age of the Late Cretaceous epoch or the lowest stage of the Upper Cretaceous series. An age is a unit of geochronology, it is a unit of time, both age and stage bear the same name. As a unit of time measure, the Cenomanian age spans the time between 100.5 ±0.9 Ma and 93.9 ±0.8 Ma. In the geologic timescale it is preceded by the Albian and is followed by the Turonian, the Cenomanian is coeval with the Woodbinian of the regional timescale of the Gulf of Mexico and the early part of the Eaglefordian of the regional timescale of the US East Coast. At the end of the Cenomanian an anoxic event took place, called the Cenomanian-Turonian boundary event or the Bonarelli Event, the Cenomanian was introduced in scientific literature by French palaeontologist Alcide dOrbigny in 1847. Its name comes from the New Latin name of the French city of Le Mans, the base of the Cenomanian stage is placed at the first appearance of foram species Rotalipora globotruncanoides in the stratigraphic record.
An official reference profile for the base of the Cenomanian is located in an outcrop at the flank of Mont Risou. The base is, in the profile, located 36 meters below the top of the Marnes Bleues Formation. The top of the Cenomanian is at the first appearance of ammonite species Watinoceras devonense, important index fossils for the Cenomanian are the ammonites Calycoceras naviculare, Acanthoceras rhotomagense and Mantelliceras mantelli. The late Cenomanian represents the highest mean sea-level observed in the Phanerozoic eon, a corollary is that the highlands were at all time lows, so the landscape on Earth was one of warm broad shallow seas inundating low-lying land areas on the precursors to todays continents. What few lands rose above the waves were made of old mountains and hills, upland plateaus, tectonic mountain building was minimal and most continents were isolated by large stretches of water. Without highlands to brake winds, the climate would have been windy and waves large, adding to the weathering, & Smith, A.
G.2004, A Geologic Time Scale 2004, Cambridge University Press. & Caron, M.2004, The Global Boundary Stratotype Section and Point for the base of the Cenomanian Stage, Mont Risou, Hautes-Alpes, Episodes 27, pp. 21–32
Sedimentary rocks are types of rock that are formed by the deposition and subsequent cementation of that material at the Earths surface and within bodies of water. Sedimentation is the name for processes that cause mineral and/or organic particles to settle in place. The particles that form a rock by accumulating are called sediment. Sedimentation may occur as minerals precipitate from solution or shells of aquatic creatures settle out of suspension. The sedimentary rock cover of the continents of the Earths crust is extensive, sedimentary rocks are only a thin veneer over a crust consisting mainly of igneous and metamorphic rocks. Sedimentary rocks are deposited in layers as strata, forming a structure called bedding, sedimentary rocks are important sources of natural resources like coal, fossil fuels, drinking water or ores. The study of the sequence of rock strata is the main source for an understanding of the Earths history, including palaeogeography, paleoclimatology. The scientific discipline that studies the properties and origin of rocks is called sedimentology.
Sedimentology is part of both geology and physical geography and overlaps partly with other disciplines in the Earth sciences, such as pedology, geochemistry, sedimentary rocks have been found on Mars. Clastic sedimentary rocks are composed of rock fragments that were cemented by silicate minerals. Clastic rocks are composed largely of quartz, rock fragments, clay minerals, and mica, any type of mineral may be present, 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 and this tripartite subdivision is mirrored by the broad categories of rudites and lutites, respectively, in older literature. The subdivision of these three categories is based on differences in clast shape and breccias), composition. Conglomerates are dominantly composed of rounded gravel, while breccias are composed of dominantly angular gravel, 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. Clean sandstones with open 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. Mudrocks are sedimentary rocks composed of at least 50% silt- and clay-sized particles and these relatively fine-grained particles are commonly transported by turbulent flow in water or air, and deposited as the flow calms and the particles settle out of suspension
West Runton is a village in North Norfolk, approximately ¼ of a mile from the North Sea coast. West Runton and East Runton together form the parish of Runton, the village straddles the A149 North Norfolk coast road and is 2½ miles west of Cromer and 1½ miles east of Sheringham. There are several shops in the village include a butcher, newsagent/general store, a post office/village store, café, furniture upholsterer, garage. A notable resident of this village is the infamous Thee of Thieves. Thee is just one of the examples of ancient Norfolk charm imortalised in the literature of the county. The pub, called the Village Inn, has a plaque on the wall that recalls a concert played at the now-demolished pavilion by the Punk band the Sex Pistols. There are two restaurants in the inn, but it does not offer accommodation, facilities are available for camping and caravanning. A noteworthy attraction of the village is The Links, a golf course designed by J. H. Taylor around the turn of the 20th century.
Another amenity of the village is Kingswood, situated in the former Runton Hill School and its former pupils include Duchess of Kent. Kingswood is an activity centre which hosts residential school trips and educational visits throughout the year. Sea defences at West Runton consist of revetments, angled sea wall and this does slow down the process of longshore drift but is used mainly as a wave break so the boats can enter the sea more easily. West Runton Pavilion and Cromer Royal Links Pavilion were two venues on the North Norfolk coast. In their heyday they hosted concerts by many of the top rock bands, West Runton Pavilion in the mid-seventies hosted appearances by bands such as the Glitter Band and Kenny and the Rubettes. Veteran performers such as Motörhead, Ian Gillan, Ozzy Osbourne and many continued to appear until 1983. Fossils of animals and insects are exposed from the eroding cliffs on the beach. The cliffs of West Runton were once part of the Cromer Forest Bed formation which is exposed at intervals along the coast of Norfolk and Suffolk, the forest bed was formed in the Quaternary Period and dates to between 700,000 and 500,000 years ago.
West Runtons most famous fossil from that period is the *West Runton elephant, in 1990 the fossilised remains were first discovered down on the beach after winter seas had eroded the cliff. The archaeologists were able to learn from the fossil that the elephant was a Mammoth and male, stood about 4 metres high and he was about 40 years old when he probably got stuck in a shallow swampy river channel
The Paleozoic Era is the earliest of three geologic eras of the Phanerozoic Eon, from 541 to 252.17 million years ago. It is the longest of the Phanerozoic eras, and is subdivided into six periods, the Cambrian, Silurian, Carboniferous. The Paleozoic comes after the Neoproterozoic era of the Proterozoic and is followed by the Mesozoic, the Paleozoic was a time of dramatic geological and evolutionary change. The Cambrian witnessed the most rapid and widespread diversification of life in Earths history, known as the Cambrian explosion, arthropods, anapsids, synapsids and diapsids all evolved during the Paleozoic. Life began in the ocean but eventually transitioned onto land, and by the late Paleozoic, Great forests of primitive plants covered the continents, many of which formed the coal beds of Europe and eastern North America. Towards the end of the era, sophisticated diapsids and synapsids were dominant, the Paleozoic Era ended with the largest extinction event in the history of Earth, the Permian–Triassic extinction event.
The effects of this catastrophe were so devastating that it took life on land 30 million years into the Mesozoic Era to recover, recovery of life in the sea may have been much faster. The Paleozoic era began and ended with supercontinents and in between were the rise of mountains along the margins, and flooding and draining of shallow seas between. At its start, the supercontinent Pannotia broke up, paleoclimatic studies and evidence of glaciers indicate that central Africa was most likely in the polar regions during the early Paleozoic. During the early Paleozoic, the huge continent Gondwana formed or was forming, by mid-Paleozoic, the collision of North America and Europe produced the Acadian-Caledonian uplifts, and a subduction plate uplifted eastern Australia. There are six periods in the Paleozoic Era, Ordovician, Devonian, the Cambrian spans from 541 million years to 485 million years and is the first period of the Paleozoic era of the Phanerozoic. The Cambrian marked a boom in evolution in an event known as the Cambrian explosion in which the largest number of creatures evolved in any period of the history of the Earth.
Creatures like algae evolved, but the most ubiquitous of that period were the armored arthropods, almost all marine phyla evolved in this period. During this time, the supercontinent Pannotia begins to break up, the Ordovician spanned from 485 million years to 443 million years ago. The Ordovician is a time in Earths history in many of the biological classes still prevalent today evolved, such as primitive fish, cephalopods. The most common forms of life, were trilobites, more importantly, the first arthropods went ashore to colonize the empty continent of Gondwana. By the end of the Ordovican, Gondwana was at the pole, early North America had collided with Europe. Glaciation of Africa resulted in a drop in sea level
The English Channel, called simply the Channel, is the body of water that separates southern England from northern France, and links the southern part of the North Sea to the Atlantic Ocean. It is about 560 km long and varies in width from 240 km at its widest to 33.3 km in the Strait of Dover and it is the smallest of the shallow seas around the continental shelf of Europe, covering an area of some 75,000 km2. The International Hydrographic Organization defines the limits of the English Channel as follows, a line joining Isle Vierge to Lands End. The southwestern limit of the North Sea, the IHO defines the southwestern limit of the North Sea as a line joining the Walde Lighthouse and Leathercoat Point. The Walde Lighthouse is 6 km east of Calais, and Leathercoat Point is at the end of St Margarets Bay. The Strait of Dover, at the Channels eastern end, is its narrowest point and it is relatively shallow, with an average depth of about 120 m at its widest part, reducing to a depth of about 45 m between Dover and Calais.
Eastwards from there the adjoining North Sea reduces to about 26 m in the Broad Fourteens where it lies over the watershed of the land bridge between East Anglia and the Low Countries. It reaches a depth of 180 m in the submerged valley of Hurds Deep,48 km west-northwest of Guernsey. The eastern region along the French coast between Cherbourg and the mouth of the Seine river at Le Havre is frequently referred to as the Bay of the Seine. There are several islands in the Channel, the most notable being the Isle of Wight off the English coast. The coastline, particularly on the French shore, is indented, several small islands close to the coastline, including Chausey. The Cotentin Peninsula in France juts out into the Channel, whilst on the English side there is a parallel channel known as the Solent between the Isle of Wight and the mainland. The Celtic Sea is to the west of the Channel, the time difference of about six hours between high water at the eastern and western limits of the Channel is indicative of the tidal range being amplified further by resonance.
It was never defined as a border and the names were more or less descriptive. It was not considered as the property of a nation, before the development of the modern nations, British scholars very often referred to it as Gaulish and the French one as British or English. The name English Channel has been used since the early 18th century. In modern Dutch, however, it is known as Het Kanaal, later, it has been known as the British Channel or the British Sea having been called the Oceanus Britannicus by the 2nd-century geographer Ptolemy. The same name is used on an Italian map of about 1450, the Anglo-Saxon texts often call it Sūð-sǣ as opposed to Norð-sǣ
Dobruja is a historical region shared today by Bulgaria and Romania. It is situated between the lower Danube River and the Black Sea, and includes the Danube Delta, Romanian coast, the territory of Dobruja is made up of Northern Dobruja, which is part of Romania, and Southern Dobruja, which belongs to Bulgaria. The territory of the Romanian region Dobrogea is now organised as the counties of Constanța and Tulcea, with an area of 15,500 km2. Its main cities are Constanța, Tulcea and Mangalia, Dobrogea is represented by dolphins in the coat of arms of Romania. The Bulgarian region of Dobrudzha is divided between the regions of Dobrich, the villages, Rainino and Madrevo. This part has an area of 7,565 km2, with a combined population of some 350,000 people. With the exception of the Danube Delta, a region located in its northeastern corner, Dobruja is hilly. The highest point is in the Țuțuiatu Peak in the Măcin Mountains, the Dobrogea Plateau covers most of the Romanian part of Dobruja, while in the Bulgarian part the Ludogorie Plateau is found.
Lake Siutghiol is one of the most important lakes in Northern Dobruja, the Black Sea exerts an influence over the regions climate, particularly within 40–60 kilometres from the coast. The average annual temperatures range from 11 °C inland and along the Danube to 11.8 °C on the coast, the coastal region of Southern Dobruja is the most arid part of Bulgaria, with an annual precipitation of 450 millimetres. Dobruja is a region once known for its windmills. About 85–90% of all experience some kind of wind, which usually comes from the north or northeast. The average wind speed is twice higher than the average in Bulgaria. Due to the precipitation and the proximity to the sea, rivers in Dobruja are usually short. However, the region has a number of shallow lakes with brackish water. The most widespread opinion among scholars is that the origin of the term Dobruja is to be found in the Turkish rendition of the name of a 14th‑century Bulgarian ruler and it was common for the Turks to name countries after one of their early rulers.
Other etymologies have been considered, but never gained widespread acceptance, abdolonyme Ubicini believed the name meant good lands, derived from Slavic dobro, an opinion that was adopted by several 19th‑century scholars. I. A. Nazarettean combines the Slavic word with the Tatar budjak, a version matching contemporaneous descriptions was suggested by Kanitz, which connected the name with the Bulgarian dobrice
Thy is a traditional district in northwestern Jutland, Denmark. It is situated north of the Limfjord, facing the North Sea and Skagerrak, the capital is Thisted population of 14.000. Snedsted and Hurup are minor towns in the area, since the Danish municipal reform of 1 January 2007, Thy is roughly identical with Thisted Municipality which belongs to the North Denmark Region. The southernmost part of Thy, the Thyholm Peninsula, belongs to Struer Municipality in the Central Denmark Region, before the merger, Thy consisted of four municipalities, Thisted and Thyholm. Thy forms the part of the North Jutlandic Island and borders Hanherred to the northeast with Vendsyssel even further northeast. In the Limfjord is the island of Mors, considered a district of Thy. Thy is traditionally regarded part of northern and western Jutland alike, the dialect belongs to the West Jutlandic group. Thy has a varied landscape. In the north it is marked by flat coastal plains which were covered by sea in neolithic times and these are interrupted with higher-lying plains that were islands in the neolithic sea.
In the slopes that formed the coast in these times, high-lying limestone is often visible - hence the name of the Limfjord. The eastern stretch, facing the Limfjord, has fertile soil, is slightly hilly and dotted with small villages. The landscape is marked by strong winds, most trees bending eastwards. The west coast has beaches and high dunes with Leymus grass. Behind the dunes, there is heath with stretches of Calluna heather, Iceland moss, crowberry, blueberry and this is the result of huge sand drifts in the 15th to 19th centuries which covered much formerly fertile land. The sand drifting affected the whole west coast of Jutland, since Thy is exposed to winds from both the north and the west, even from the North Atlantic, the sand drift went the furthest inland in this area, as far as 18 km. Parts of the sandy stretches have been turned into conifer woods, a line of lakes, believed to have been caused by the sand drifts blocking the outflow to the sea, mark the border between the western, sparsely populated sandy area and the eastern, fertile farmland.
The wetlands Vejlerne in the northeast are the largest bird sanctuary in Northern Europe, nearby is the bird cliff Bulbjerg. On 22 August 2008 Thy National Park officially opened, as the first of three realized national parks out of seven planned
Ohio /oʊˈhaɪ. oʊ/ is a Midwestern state in the Great Lakes region of the United States. Ohio is the 34th largest by area, the 7th most populous, the states capital and largest city is Columbus. The state takes its name from the Ohio River, the name originated from the Iroquois word ohi-yo’, meaning great river or large creek. Partitioned from the Northwest Territory, the state was admitted to the Union as the 17th state on March 1,1803, Ohio is historically known as the Buckeye State after its Ohio buckeye trees, and Ohioans are known as Buckeyes. Ohio occupies 16 seats in the United States House of Representatives, Ohio is known for its status as both a swing state and a bellwether in national elections. Six Presidents of the United States have been elected who had Ohio as their home state, Ohios geographic location has proven to be an asset for economic growth and expansion. Because Ohio links the Northeast to the Midwest, much cargo, Ohio has the nations 10th largest highway network, and is within a one-day drive of 50% of North Americas population and 70% of North Americas manufacturing capacity.
To the north, Lake Erie gives Ohio 312 miles of coastline, Ohios southern border is defined by the Ohio River, and much of the northern border is defined by Lake Erie. Ohios neighbors are Pennsylvania to the east, Michigan to the northwest, Ontario Canada, to the north, Indiana to the west, Kentucky on the south, Ohio is bounded by the Ohio River, but nearly all of the river itself belongs to Kentucky and West Virginia. Ohio has only that portion of the river between the rivers 1792 low-water mark and the present high-water mark, the border with Michigan has changed, as a result of the Toledo War, to angle slightly northeast to the north shore of the mouth of the Maumee River. Much of Ohio features glaciated plains, with a flat area in the northwest being known as the Great Black Swamp. Most of Ohio is of low relief, but the unglaciated Allegheny Plateau features rugged hills, in 1965 the United States Congress passed the Appalachian Regional Development Act, at attempt to address the persistent poverty and growing economic despair of the Appalachian Region.
This act defines 29 Ohio counties as part of Appalachia, the worst weather disaster in Ohio history occurred along the Great Miami River in 1913. Known as the Great Dayton Flood, the entire Miami River watershed flooded, as a result, the Miami Conservancy District was created as the first major flood plain engineering project in Ohio and the United States. Grand Lake St. Marys in the west central part of the state was constructed as a supply of water for canals in the era of 1820–1850. For many years this body of water, over 20 square miles, was the largest artificial lake in the world and it should be noted that Ohios canal-building projects were not the economic fiasco that similar efforts were in other states. Some cities, such as Dayton, owe their emergence to location on canals. Summers are typically hot and humid throughout the state, while winters generally range from cool to cold, precipitation in Ohio is moderate year-round
Limestone is a sedimentary rock, composed mainly of skeletal fragments of marine organisms such as coral and molluscs. Its major materials are the minerals calcite and aragonite, which are different crystal forms of calcium carbonate, about 10% of sedimentary rocks are limestones. The solubility of limestone in water and weak acid solutions leads to karst landscapes, most cave systems are through limestone bedrock. The first geologist to distinguish limestone from dolomite was Belsazar Hacquet in 1778, like most other sedimentary rocks, most limestone is composed of grains. Most grains in limestone are skeletal fragments of organisms such as coral or foraminifera. Other carbonate grains comprising limestones are ooids, peloids and these organisms secrete shells made of aragonite or calcite, and leave these shells behind when they die. Limestone often contains variable amounts of silica in the form of chert or siliceous skeletal fragment, some limestones do not consist of grains at all, and are formed completely by the chemical precipitation of calcite or aragonite, i. e. travertine.
Secondary calcite may be deposited by supersaturated meteoric waters and this produces speleothems, such as stalagmites and stalactites. Another form taken by calcite is oolitic limestone, which can be recognized by its granular appearance, the primary source of the calcite in limestone is most commonly marine organisms. Some of these organisms can construct mounds of rock known as reefs, below about 3,000 meters, water pressure and temperature conditions cause the dissolution of calcite to increase nonlinearly, so limestone typically does not form in deeper waters. Limestones may form in lacustrine and evaporite depositional environments, calcite can be dissolved or precipitated by groundwater, depending on several factors, including the water temperature, pH, and dissolved ion concentrations. Calcite exhibits a characteristic called retrograde solubility, in which it becomes less soluble in water as the temperature increases. Impurities will cause limestones to exhibit different colors, especially with weathered surfaces, Limestone may be crystalline, granular, or massive, depending on the method of formation.
Crystals of calcite, dolomite or barite may line small cavities in the rock, when conditions are right for precipitation, calcite forms mineral coatings that cement the existing rock grains together, or it can fill fractures. Travertine is a banded, compact variety of limestone formed along streams, particularly there are waterfalls. Calcium carbonate is deposited where evaporation of the leaves a solution supersaturated with the chemical constituents of calcite. Tufa, a porous or cellular variety of travertine, is found near waterfalls, coquina is a poorly consolidated limestone composed of pieces of coral or shells. During regional metamorphism that occurs during the building process, limestone recrystallizes into marble