A port is a maritime commercial facility which may comprise one or more wharves where ships may dock to load and discharge passengers and cargo. Although situated on a sea coast or estuary, some ports, such as Hamburg and Duluth, are many miles inland, with access from the sea via river or canal. Today, by far the greatest growth in port development is in Asia, the continent with some of the world's largest and busiest ports, such as Singapore and the Chinese ports of Shanghai and Ningbo-Zhoushan. Whenever ancient civilisations engaged in maritime trade, they tended to develop sea ports. One of the world's oldest known artificial harbors is at Wadi al-Jarf on the Red Sea. Along with the finding of harbor structures, ancient anchors have been found. Other ancient ports include Guangzhou during Qin Dynasty China and Canopus, the principal Egyptian port for Greek trade before the foundation of Alexandria. In ancient Greece, Athens' port of Piraeus was the base for the Athenian fleet which played a crucial role in the Battle of Salamis against the Persians in 480 BCE.
In ancient India from 3700 BCE, Lothal was a prominent city of the Indus valley civilisation, located in the Bhāl region of the modern state of Gujarāt. Ostia Antica was the port of ancient Rome with Portus established by Claudius and enlarged by Trajan to supplement the nearby port of Ostia. In Japan, during the Edo period, the island of Dejima was the only port open for trade with Europe and received only a single Dutch ship per year, whereas Osaka was the largest domestic port and the main trade hub for rice. Nowadays, many of these ancient sites no longer function as modern ports. In more recent times, ports sometimes fall out of use. Rye, East Sussex, was an important English port in the Middle Ages, but the coastline changed and it is now 2 miles from the sea, while the ports of Ravenspurn and Dunwich have been lost to coastal erosion. Whereas early ports tended to be just simple harbours, modern ports tend to be multimodal distribution hubs, with transport links using sea, canal, road and air routes.
Successful ports are located to optimize access to an active hinterland, such as the London Gateway. Ideally, a port will grant easy navigation to ships, will give shelter from wind and waves. Ports are on estuaries, where the water may be shallow and may need regular dredging. Deep water ports such as Milford Haven are less common, but can handle larger ships with a greater draft, such as super tankers, Post-Panamax vessels and large container ships. Other businesses such as regional distribution centres and freight-forwarders and other processing facilities find it advantageous to be located within a port or nearby. Modern ports will have specialised cargo-handling equipment, such as gantry cranes, reach stackers and forklift trucks. Ports have specialised functions: some tend to cater for passenger ferries and cruise ships; some third world countries and small islands such as Ascension and St Helena still have limited port facilities, so that ships must anchor off while their cargo and passengers are taken ashore by barge or launch.
In modern times, ports decline, depending on current economic trends. In the UK, both the ports of Liverpool and Southampton were once significant in the transatlantic passenger liner business. Once airliner traffic decimated that trade, both ports diversified to container cargo and cruise ships. Up until the 1950s the Port of London was a major international port on the River Thames, but changes in shipping and the use of containers and larger ships, have led to its decline. Thamesport, a small semi-automated container port thrived for some years, but has been hit hard by competition from the emergent London Gateway port and logistics hub. In mainland Europe, it is normal for ports to be publicly owned, so that, for instance, the ports of Rotterdam and Amsterdam are owned by the state and by the cities themselves. By contrast, in the UK all ports are in private hands, such as Peel Ports who own the Port of Liverpool, John Lennon Airport and the Manchester Ship Canal. Though modern ships tend to have bow-thrusters and stern-thrusters, many port authorities still require vessels to use pilots and tugboats for manoeuvering large ships in tight quarters.
For instance, ships approaching the Belgian port of Antwerp, an inland port on the River Scheldt, are obliged to use Dutch pilots when navigating on that part of the estuary that belongs to the Netherlands. Ports with international traffic have customs facilities; the terms "port" and "seaport" are used for different types of port facilities that handle ocean-going vessels, river port is used for river traffic, such as barges and other shallow-draft vessels. A dry port is an inland intermodal terminal directly connected by road or rail to a seaport and operating as a centre for the transshipment of sea cargo to inland destinations. A fishing port is a harbor for landing and distributing fish, it may be a recreational facility, but it is commercial. A fishing port is the only port that depends on an ocean product, depletion of fish may cause a fishing port to be uneconomical. An inland port is a port on a navigable lake, river, or canal with access to a sea or ocean, which therefore allows a ship to sail from the ocean inland to the port to load or unload its cargo.
An example of this is the St. Lawrence Seaway which allows ships to travel from the Atlantic Ocean several thousand kilometers inland to Great Lakes ports like Toronto, Duluth-Superior, C
Fishing is the activity of trying to catch fish. Fish are caught in the wild. Techniques for catching fish include hand gathering, netting and trapping. “Fishing” may include catching aquatic animals other than fish, such as molluscs, cephalopods and echinoderms. The term is not applied to catching farmed fish, or to aquatic mammals, such as whales where the term whaling is more appropriate. In addition to being caught to be eaten, fish are caught as recreational pastimes. Fishing tournaments are held, caught fish are sometimes kept as preserved or living trophies; when bioblitzes occur, fish are caught and released. According to the United Nations FAO statistics, the total number of commercial fishermen and fish farmers is estimated to be 38 million. Fisheries and aquaculture provide direct and indirect employment to over 500 million people in developing countries. In 2005, the worldwide per capita consumption of fish captured from wild fisheries was 14.4 kilograms, with an additional 7.4 kilograms harvested from fish farms.
Fishing is an ancient practice that dates back to at least the beginning of the Upper Paleolithic period about 40,000 years ago. Isotopic analysis of the skeletal remains of Tianyuan man, a 40,000-year-old modern human from eastern Asia, has shown that he consumed freshwater fish. Archaeology features such as shell middens, discarded fish bones, cave paintings show that sea foods were important for survival and consumed in significant quantities. Fishing in Africa is evident early on in human history. Neanderthals were fishing by about 200,000 BC to have a source of food for their families and to trade or sell. People could have developed basketry for fish traps, spinning and early forms of knitting in order to make fishing nets to be able to catch more fish in larger quantities. During this period, most people lived a hunter-gatherer lifestyle and were, of necessity on the move. However, where there are early examples of permanent settlements such as those at Lepenski Vir, they are always associated with fishing as a major source of food.
The British dogger was an early type of sailing trawler from the 17th century, but the modern fishing trawler was developed in the 19th century, at the English fishing port of Brixham. By the early 19th century, the fishermen at Brixham needed to expand their fishing area further than before due to the ongoing depletion of stocks, occurring in the overfished waters of South Devon; the Brixham trawler that evolved there was of a sleek build and had a tall gaff rig, which gave the vessel sufficient speed to make long distance trips out to the fishing grounds in the ocean. They were sufficiently robust to be able to tow large trawls in deep water; the great trawling fleet that built up at Brixham, earned the village the title of'Mother of Deep-Sea Fisheries'. This revolutionary design made large scale trawling in the ocean possible for the first time, resulting in a massive migration of fishermen from the ports in the South of England, to villages further north, such as Scarborough, Grimsby and Yarmouth, that were points of access to the large fishing grounds in the Atlantic Ocean.
The small village of Grimsby grew to become the largest fishing port in the world by the mid 19th century. An Act of Parliament was first obtained in 1796, which authorised the construction of new quays and dredging of the Haven to make it deeper, it was only in the 1846, with the tremendous expansion in the fishing industry, that the Grimsby Dock Company was formed. The foundation stone for the Royal Dock was laid by Albert the Prince consort in 1849; the dock covered 25 acres and was formally opened by Queen Victoria in 1854 as the first modern fishing port. The elegant Brixham trawler spread across the world. By the end of the 19th century, there were over 3,000 fishing trawlers in commission in Britain, with 1,000 at Grimsby; these trawlers were sold to fishermen including from the Netherlands and Scandinavia. Twelve trawlers went on to form the nucleus of the German fishing fleet; the earliest steam powered fishing boats first appeared in the 1870s and used the trawl system of fishing as well as lines and drift nets.
These were large boats 80–90 feet in length with a beam of around 20 feet. They travelled at 9 -- 11 knots; the earliest purpose built fishing vessels were designed and made by David Allan in Leith, Scotland in March 1875, when he converted a drifter to steam power. In 1877, he built. Steam trawlers were introduced at Hull in the 1880s. In 1890 it was estimated; the steam drifter was not used in the herring fishery until 1897. The last sailing fishing trawler was built in 1925 in Grimsby. Trawler designs adapted as the way they were powered changed from sail to coal-fired steam by World War I to diesel and turbines by the end of World War II. In 1931, the first powered drum was created by Laurie Jarelainen; the drum was a circular device, set to the side of the boat and would draw in the nets. Since World War II, radio navigation aids and fish finders have been used; the first trawlers fished over the side, rather than over the stern. The first purpose built stern trawler was Fairtry built in 1953 at Scotland.
The ship was much larger than any other trawlers in operation and inaugurated the era of the'super trawler'. As the ship pulled its nets over the stern, it could lift out a much greater haul of up to 60 tons; the ship served as a basis for the expansion of'su
Departments of France
In the administrative divisions of France, the department is one of the three levels of government below the national level, between the administrative regions and the commune. Ninety-six departments are in metropolitan France, five are overseas departments, which are classified as regions. Departments are further subdivided into 334 arrondissements, themselves divided into cantons; each department is administered by an elected body called a departmental council. From 1800 to April 2015, these were called general councils; each council has a president. Their main areas of responsibility include the management of a number of social and welfare allowances, of junior high school buildings and technical staff, local roads and school and rural buses, a contribution to municipal infrastructures. Local services of the state administration are traditionally organised at departmental level, where the prefect represents the government; the departments were created in 1790 as a rational replacement of Ancien Régime provinces with a view to strengthen national unity.
All of them were named after physical geographical features, rather than after historical or cultural territories which could have their own loyalties. The division of France into departments was a project identified with the French revolutionary leader the Abbé Sieyès, although it had been discussed and written about by many politicians and thinkers; the earliest known suggestion of it is from 1764 in the writings of d'Argenson. They have inspired similar divisions in some of them former French colonies. Most French departments are assigned a two-digit number, the "Official Geographical Code", allocated by the Institut national de la statistique et des études économiques. Overseas departments have a three-digit number; the number is used, for example, in the postal code, was until used for all vehicle registration plates. While residents use the numbers to refer to their own department or a neighbouring one, more distant departments are referred to by their names, as few people know the numbers of all the departments.
For example, inhabitants of Loiret might refer to their department as "the 45". In 2014, President François Hollande proposed to abolish departmental councils by 2020, which would have maintained the departments as administrative divisions, to transfer their powers to other levels of governance; this reform project has since been abandoned. The first French territorial departments were proposed in 1665 by Marc-René d'Argenson to serve as administrative areas purely for the Ponts et Chaussées infrastructure administration. Before the French Revolution, France gained territory through the annexation of a mosaic of independent entities. By the close of the Ancien Régime, it was organised into provinces. During the period of the Revolution, these were dissolved in order to weaken old loyalties; the modern departments, as all-purpose units of the government, were created on 4 March 1790 by the National Constituent Assembly to replace the provinces with what the Assembly deemed a more rational structure.
Their boundaries served two purposes: Boundaries were chosen to break up France's historical regions in an attempt to erase cultural differences and build a more homogeneous nation. Boundaries were set so that every settlement in the country was within a day's ride of the capital of a department; this was a security measure, intended to keep the entire national territory under close control. This measure was directly inspired by the Great Terror, during which the government had lost control of many rural areas far from any centre of government; the old nomenclature was avoided in naming the new departments. Most were named after other physical features. Paris was in the department of Seine. Savoy became the department of Mont-Blanc; the number of departments 83, had been increased to 130 by 1809 with the territorial gains of the Republic and of the First French Empire. Following Napoleon's defeats in 1814–1815, the Congress of Vienna returned France to its pre-war size and the number of departments was reduced to 86.
In 1860, France acquired the County of Nice and Savoy, which led to the creation of three new departments. Two were added from the new Savoyard territory, while the department of Alpes-Maritimes was created from Nice and a portion of the Var department; the 89 departments were given numbers based on the alphabetical order of their names. The department of Bas-Rhin and parts of Meurthe, Moselle and Haut-Rhin were ceded to the German Empire in 1871, following France's defeat in the Franco-Prussian War. A small part of Haut-Rhin became known as the Territoire de Belfort; when France regained the ceded departments after World War I, the Territoire de Belfort was not re-integrated into Haut-Rhin. In 1922, it became France's 90th department; the Lorraine departments were not changed back to their original boundaries, a new Moselle department was created in the regaine
Normandy is one of the 18 regions of France referring to the historical Duchy of Normandy. Normandy is divided into five administrative departments: Calvados, Manche and Seine-Maritime, it covers 30,627 square kilometres, comprising 5% of the territory of metropolitan France. Its population of 3.37 million accounts for around 5% of the population of France. The inhabitants of Normandy are known as Normans, the region is the historic homeland of the Norman language; the historical region of Normandy comprised the present-day region of Normandy, as well as small areas now part of the departments of Mayenne and Sarthe. The Channel Islands are historically part of Normandy. Normandy's name comes from the settlement of the territory by Danish and Norwegian Vikings from the 9th century, confirmed by treaty in the 10th century between King Charles III of France and the Viking jarl Rollo. For a century and a half following the Norman conquest of England in 1066, Normandy and England were linked by Norman and Frankish rulers.
Archaeological finds, such as cave paintings, prove that humans were present in the region in prehistoric times. Celts invaded Normandy in successive waves from the 4th to the 3rd century BC; when Julius Caesar invaded Gaul, there were nine different Celtic tribes living in Normandy. The Romanisation of Normandy was achieved by the usual methods: Roman roads and a policy of urbanisation. Classicists have knowledge of many Gallo-Roman villas in Normandy. In the late 3rd century, barbarian raids devastated Normandy. Coastal settlements were raided by Saxon pirates. Christianity began to enter the area during this period. In 406, Germanic tribes began invading from the east; as early as 487, the area between the River Somme and the River Loire came under the control of the Frankish lord Clovis. Vikings started to raid the Seine valley during the middle of the 9th century; as early as 841, a Viking fleet appeared at the mouth of the Seine, the principal route by which they entered the kingdom. After attacking and destroying monasteries, including one at Jumièges, they took advantage of the power vacuum created by the disintegration of Charlemagne's empire to take northern France.
The fiefdom of Normandy was created for Rollo. Rollo had besieged Paris but in 911 entered vassalage to the king of the West Franks, Charles the Simple, through the Treaty of Saint-Clair-sur-Epte. In exchange for his homage and fealty, Rollo gained the territory which he and his Viking allies had conquered; the name "Normandy" reflects Rollo's Viking origins. To this day, in Norwegian language the word nordmann denotes a Norwegian person; the descendants of Rollo and his followers adopted the local Gallo-Romance language and intermarried with the area's native Gallo-Roman inhabitants. They became the Normans – a Norman-speaking mixture of Norsemen and indigenous Franks and Romans. Rollo's descendant William became king of England in 1066 after defeating Harold Godwinson, the last of the Anglo-Saxon kings, at the Battle of Hastings, while retaining the fiefdom of Normandy for himself and his descendants. Besides the conquest of England and the subsequent subjugation of Wales and Ireland, the Normans expanded into other areas.
Norman families, such as that of Tancred of Hauteville, Rainulf Drengot and Guimond de Moulins played important parts in the conquest of southern Italy and the Crusades. The Drengot lineage, de Hauteville's sons William Iron Arm and Humphrey, Robert Guiscard and Roger the Great Count progressively claimed territories in southern Italy until founding the Kingdom of Sicily in 1130, they carved out a place for themselves and their descendants in the Crusader states of Asia Minor and the Holy Land. The 14th-century explorer Jean de Béthencourt established a kingdom in the Canary Islands in 1404, he received the title King of the Canary Islands from Pope Innocent VII but recognized Henry III of Castile as his overlord, who had provided him aid during the conquest. In 1204, during the reign of John Lackland, mainland Normandy was taken from England by France under King Philip II. Insular Normandy remained however under English control. In 1259, Henry III of England recognized the legality of French possession of mainland Normandy under the Treaty of Paris.
His successors, however fought to regain control of their ancient fiefdom. The Charte aux Normands granted by Louis X of France in 1315 – like the analogous Magna Carta granted in England in the aftermath of 1204 – guaranteed the liberties and privileges of the province of Normandy. French Normandy was occupied by English forces during the Hundred Years' War in 1345–1360 and again in 1415–1450. Normandy lost three-quarters of its population during the war. Afterward prosperity returned to Normandy until the Wars of Religion; when many Norman towns joined the Protestant Reformation, battles ensued throughout the province. In the Channel Islands, a period of Calvinism following the Reformation was suppressed when Anglicanism was imposed following the English Civil War. Samuel de Champlain founded Acadia. Four years
Hundred Years' War
The Hundred Years' War was a series of conflicts waged from 1337 to 1453 by the House of Plantagenet, rulers of the Kingdom of England, against the French House of Valois, over the right to rule the Kingdom of France. Each side drew many allies into the war, it was one of the most notable conflicts of the Middle Ages, in which five generations of kings from two rival dynasties fought for the throne of the largest kingdom in Western Europe. The war marked both the height of chivalry and its subsequent decline, the development of strong national identities in both countries. Tensions between the crowns of France and England can be traced back to the origins of the English royal family itself, French in origin. For this reason, English monarchs had held not only the English Crown, but titles and lands within France, the possession of which made them vassals to the kings of France; the status of the English King's French fiefs was a major source of conflict between the two monarchies throughout the Middle Ages.
French monarchs systematically sought to check the growth of English power, stripping away lands as the opportunity arose whenever England was at war with Scotland, an ally of France. Over the centuries, English holdings in France had varied in size, at some points dwarfing the French royal domain. In 1316, a principle was established denying women succession to the French throne. In 1328, Charles IV of France died without brothers, his closest male relative was his nephew Edward III of England, whose mother, Isabella of France, was sister of the deceased King. Isabella claimed the throne of France for her son, but the French rejected it, maintaining that Isabella could not transmit a right she did not possess. Furthermore, political sentiment favoured a Frenchman for the crown rather than a foreign prince; the throne passed instead to Philip, Count of Valois, a patrilineal cousin of Charles IV, who would become Philip VI of France, the first king of the House of Valois. The English had not expected their claim to meet with success, did not press the matter when it was denied.
However, disagreements between Philip and Edward induced the former to confiscate the latter's lands in France, in turn prompted Edward III to reassert his claim to the French throne. Several overwhelming English victories in the war—especially at Crécy, Agincourt—raised the prospects of an ultimate English triumph, convinced the English to continue pouring money and manpower into the war over many decades. However, the greater resources of the French monarchy prevented the English kings from completing the conquest of France. Starting in 1429, decisive French victories at Orléans, Patay and Castillon concluded the war in favour of the House of Valois, with England permanently losing most of its possessions on the continent. Historians divide the war into three phases separated by truces: the Edwardian War, the Caroline War, the Lancastrian War. Local conflicts in neighbouring areas, which were contemporarily related to the war, including the War of the Breton Succession, the Castilian Civil War, the War of the Two Peters in Aragon, the 1383–85 crisis in Portugal, were availed by the parties to advance their agendas.
Historians adopted the term "Hundred Years' War" as a historiographical periodisation to encompass all of these events, thus constructing the longest military conflict in European history. The war owes its historical significance to multiple factors. By its end, feudal armies had been replaced by professional troops, aristocratic dominance had yielded to a democratisation of the manpower and weapons of armies. Although a dynastic conflict, the war gave impetus to ideas of French and English nationalism; the wider introduction of weapons and tactics supplanted the feudal armies where heavy cavalry had dominated, artillery became important. The war precipitated the creation of the first standing armies in Western Europe since the time of the Western Roman Empire, thus helping to change their role in warfare. With respect to the belligerents, in France, civil wars, deadly epidemics and bandit free-companies of mercenaries reduced the population drastically. In England, political forces over time came to oppose the costly venture.
The dissatisfaction of English nobles, resulting from the loss of their continental landholdings, as well as the general shock at losing a war in which investment had been so great, became factors leading to the Wars of the Roses. The root causes of the conflict can be found in the demographic and political crises of 14th century Europe; the outbreak of war was motivated by a gradual rise in tension between the kings of France and England about Gascony and Scotland. The dynastic question, which arose due to an interruption of the direct male line of the Capetians, was the official pretext; the question of female succession to the French throne was raised after the death of Louis X in 1316. Louis X left only a daughter, his posthumous son John I lived only a few days. Furthermore, the paternity of his daughter was in question, as her mother, Margaret of Burgundy, had been exposed as an adulterer in the Tour de Nesle affair. Philip, Count of Poitiers, brother of Louis X, positioned himself to take the crown, advancing the stance that women should be ineligible to succeed to the French throne.
Through his political sagacity he won over his adversaries and succeeded to the French throne as Philip V. By the same law that he procured, his daughters were denied the succession, whi
Relative humidity is the ratio of the partial pressure of water vapor to the equilibrium vapor pressure of water at a given temperature. Relative humidity depends on the pressure of the system of interest; the same amount of water vapor results in higher relative humidity in cool air than warm air. A related parameter is that of dewpoint; the relative humidity of an air–water mixture is defined as the ratio of the partial pressure of water vapor in the mixture to the equilibrium vapor pressure of water over a flat surface of pure water at a given temperature: ϕ = p H 2 O p H 2 O ∗. Relative humidity is expressed as a percentage. At 100 % relative humidity, the air is at its dewpoint. Climate control refers to the control of temperature and relative humidity in buildings and other enclosed spaces for the purpose of providing for human comfort and safety, of meeting environmental requirements of machines, sensitive materials and technical processes. Along with air temperature, mean radiant temperature, air speed, metabolic rate, clothing level, relative humidity plays a role in human thermal comfort.
According to ASHRAE Standard 55-2017: Thermal Environmental Conditions for Human Occupancy, indoor thermal comfort can be achieved through the PMV method with relative humidities ranging from 0% to 100%, depending on the levels of the other factors contributing to thermal comfort. However, the recommended range of indoor relative humidity in air conditioned buildings is 30-60%. In general, higher temperatures will require lower relative humidities to achieve thermal comfort compared to lower temperatures, with all other factors held constant. For example, with clothing level = 1, Metabolic rate = 1.1, air speed 0.1 m/s, a change in air temperature and mean radiant temperature from 20 degrees C to 24 degrees C would lower the maximum acceptable relative humidity from 100% to 65% to maintain thermal comfort conditions. The CBE Thermal Comfort Tool can be used to demonstrate the effect of relative humidity for specific thermal comfort conditions and it can be used to demonstrate compliance with ASHRAE Standard 55-2017.
When using the adaptive model to predict thermal comfort indoors, relative humidity is not taken into account. Although relative humidity is an important factor for thermal comfort, humans are more sensitive to variations in temperature than they are to changes in relative humidity. Relative humidity has a small effect on thermal comfort outdoors when air temperatures are low, a more pronounced effect at moderate air temperatures, a much stronger influence at higher air temperatures. In cold climates, the outdoor temperature causes lower capacity for water vapor to flow about, thus although it may be snowing and the relative humidity outdoors is high, once that air comes into a building and heats up, its new relative humidity is low, making the air dry, which can cause discomfort. Dry cracked. Low humidity causes tissue lining nasal passages to dry and become more susceptible to penetration of Rhinovirus cold viruses. Low humidity is a common cause of nosebleeds; the use of a humidifier in homes bedrooms, can help with these symptoms.
Indoor relative humidities should be kept above 30% to reduce the likelihood of the occupant's nasal passages drying out. Humans can be comfortable within a wide range of humidities depending on the temperature—from 30% to 70%—but ideally between 50% and 60%. Low humidity can create discomfort, respiratory problems, aggravate allergies in some individuals. In the winter, it is advisable to maintain relative humidity above. Low relative humidities may cause eye irritation. For climate control in buildings using HVAC systems, the key is to maintain the relative humidity at a comfortable range—low enough to be comfortable but high enough to avoid problems associated with dry air; when the temperature is high and the relative humidity is low, evaporation of water is rapid. Wooden furniture can shrink; when the temperature is low and the relative humidity is high, evaporation of water is slow. When relative humidity approaches 100 percent, condensation can occur on surfaces, leading to problems with mold, corrosion and other moisture-related deterioration.
Condensation can pose a safety risk as it can promote the growth of mold and wood rot as well as freezing emergency exits shut. Certain production and technical processes and treatments in factories, laboratories and other facilities require specific relative humidity levels to be maintained using humidifiers and associated control systems; the basic principles for buildings, above apply to vehicles. In addition, there may be safety considerations. For instance, high humidity inside a vehicle can lead to problems of condensation, such
A pebble is a clast of rock with a particle size of 2 to 64 millimetres based on the Krumbein phi scale of sedimentology. Pebbles are considered larger than granules and smaller than cobbles. A rock made predominantly of pebbles is termed a conglomerate. Pebble tools are among the earliest known man-made artifacts, dating from the Palaeolithic period of human history. A beach composed chiefly of surface pebbles is termed a shingle beach; this type of beach has armoring characteristics with respect to wave erosion, as well as ecological niches that provide habitat for animals and plants. Inshore banks of shingle exist in some locations, such as the entrance to the River Ore, where the moving banks of shingle give notable navigational challenges. Pebbles come in various colors and textures and can have streaks, known as veins, of quartz or other minerals. Pebbles are smooth but, dependent on how they come in contact with the sea, they can have marks of contact with other rocks or other pebbles. Pebbles left above the high water mark may have growths of organisms such as lichen on them, signifying the lack of contact with seawater.
Pebbles are found in two locations – on the beaches of various oceans and seas, inland where ancient seas used to cover the land. When the seas retreated, the rocks became landlocked, they can be found in lakes and ponds. Pebbles can form in rivers, travel into estuaries where the smoothing continues in the sea. Beach pebbles and river pebbles are distinct in their geological appearance. Beach pebbles form over time as the ocean water washes over loose rock particles; the result is a rounded appearance. The typical size range is from 2 mm to 50 mm; the colors range from translucent white to black, include shades of yellow, brown and green. Some of the more plentiful pebble beaches are found along the coast of the Pacific Ocean, beginning in the United States and extending down to the tip of South America in Argentina. Other pebble beaches are found in northern Europe, along the coast of the U. K. and Ireland, on the shores of Australia, around the islands of Indonesia and Japan. Inland pebbles are found along the shores of large rivers and lakes.
These pebbles form as the flowing water washes over rock particles on the bottom and along the shores of the river. The smoothness and color of river pebbles depends on several factors, such as the composition of the soil of the river banks, the chemical characteristics of the water, the speed of the current; because river current is gentler than the ocean waves, river pebbles are not as smooth as beach pebbles. The most common colors of river rock are black, green and white. Beach pebbles and river pebbles are used for a variety of both outdoors and indoors, they can be sorted by colour and size, they can be polished to improve the texture and colour. Outdoors, beach pebbles are used for landscaping, construction and as decorative elements. Beach pebbles are used to cover walkways and driveways, around pools, in and around plant containers, on patios and decks. Beach and river pebbles are used to create water-smart gardens in areas where water is scarce. Small pebbles are used to create living spaces and gardens on the rooftops of buildings.
Indoors, pebbles can be used as paperweights. Large pebbles are used to create "pet rocks" for children. On Mars, slabs of pebbly conglomerate rock have been found and have been interpreted by scientists as having formed in an ancient streambed; the gravels, which were discovered by NASA's Mars rover Curiosity, range from the size of sand particles to the size of golf balls. Analysis has shown that the pebbles were deposited by a stream that flowed at walking pace and was ankle- to hip-deep. Gravel Japanese Garden of Peace Media related to Pebbles at Wikimedia Commons