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25-573: The name of the river is derived from the Czech word bílá (i.e. 'white'). Names of rivers with this colour in the name often referred to the stony or pebbly nature of the river bed. The Bílina originates in the territory of Blatno in the Ore Mountains at an elevation of 823 m (2,700 ft) and flows to Ústí nad Labem , where it enters the Elbe River at an elevation of 133 m (436 ft). It

50-555: A pebble and smaller than a boulder . Other scales define a cobble's size differently. A rock made predominantly of cobbles is termed a conglomerate . Cobblestone is a building material based on cobbles. Cobbles, also called cobblestones , derive their name from the word cob , meaning a rounded lump. The term is further related to the German Kopf , meaning head . Chester Wentworth referred to cobbles as cobble bowlders [ sic ] in his 1922 paper that would become

75-731: Is 82.0 km (51.0 mi) long. Its drainage basin has an area of 1,082.5 km (418.0 sq mi). The longest tributaries of the Bílina are: The river flows through the densely populated area of the Most Basin . The most notable settlements on the river are the cities of Ústí nad Labem and Most . The river flows through the municipal territories of Blatno , Boleboř , Jirkov , Vrskmaň , Horní Jiřetín , Litvínov , Most, Obrnice , Želenice , Bílina , Světec , Hostomice , Ohníč , Bžany , Bystřany , Rtyně nad Bílinou , Řehlovice , Trmice and Ústí nad Labem. Two reservoirs are built on

100-535: 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 commonly 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 (large quantities of pebbles) exist in some locations, such as

125-417: Is to construct meanders and pools, extend the flow path and reduce the slope of the bottom. The improvement of water purity led to the return of fish, and already in 2006 most of the species typical of Czech rivers were found in it, e.g. Eurasian carp , perch and common bream . New fish are introduced into the river twice a year. The Bílina is suitable for river tourism . About 50 km (31 mi) of

150-846: The United States Department of Agriculture 's definition suggests a range of 75–250 millimeters (3.0–9.8 in) and the ISO standard 14688 names cobbles as ranging from 63–200 millimeters (2.5–7.9 in) in diameter. Various attempts have been made to refine the Udden–Wentworth scale, including its definition of cobbles. In 1968, D. J. Doeglas proposed subdividing the cobble designation into two fractions, small cobbles (for particles with diameters from 64–125 millimeters [2.5–4.9 in]) and large cobbles (for particles with diameters from 125–250 millimeters [4.9–9.8 in]). A 1999 paper by Terence C. Blair and John G. McPherson argued that

175-429: The high water mark may have growths of organisms such as lichen on them, signifying the lack of contact with seawater . Pebbles on Earth exist in two types of locations – on the beaches of various oceans and seas, and inland where ancient seas used to cover the land. Then, when the seas retreated, the rocks became landlocked. Here, they entered lakes and ponds, and form in rivers , travelling into estuaries where

200-411: The Udden–Wentworth and Krumbein scales betrayed a historical emphasis on the study of sand grains while ignoring larger gravel grains. They proposed defining fine cobbles as those with diameters from 64–128 millimeters (2.5–5.0 in) (−6 to −7 φ) and coarse cobbles as those with diameters from 128–256 millimeters (5.0–10.1 in) (−7 to −8 φ). In 2012, Simon J. Blott and Kenneth Pye suggested that

225-473: The Udden–Wentworth scale, an unlithified fraction of cobbles is classified as gravel while a lithified sample primarily composed of cobbles is a conglomerate . The Committee on Sedimentation of the US National Research Council has recommended that in situ cobbles be identified by their process of origination, if possible (e.g., cobbles by disintegration , by exfoliation , etc.). In

250-540: The basis for the Udden–Wentworth scale. Within the widely used Krumbein phi scale of grain sizes , cobbles are defined as clasts of rock ranging from −6 to −8 φ. This classification corresponds with the Udden–Wentworth size scale which defines cobbles as clasts with diameters from 64–256 millimeters (2.5–10.1 in). On this scale, cobbles are larger than pebbles which measure 4–64 millimeters (0.16–2.52 in) in diameter and smaller than boulders, whose diameters range from 256–4,096 millimeters (10.1–161.3 in). On

275-512: The beaches of the Norwegian Sea ), along the coast of the U.K. and Ireland, on the shores of Australia, and around the islands of Indonesia and Japan. Inland pebbles (river pebbles of river rock) are usually 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

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300-422: The cobble designation be eliminated altogether, replaced by very small boulder and small boulder designations equivalent in size to Blair and McPherson's fine and coarse cobbles, respectively. When occurring in streams, cobbles are likely to be found in mountain valley streambeds that are moderately steep. Cobbles are also transported by glaciers and deposited as with other grades of sediment as till . If

325-496: The composition of the soil of the river banks, the chemical characteristics of the water, and the speed of the current . Because river current is gentler than the ocean waves , river pebbles are usually not as smooth as beach pebbles. The most common colors of river rock are black, grey, green, brown and white. Beach pebbles and river pebbles are used for a variety of purposes, both outdoors and indoors. They can be sorted by colour and size, and they can also be polished to improve

350-491: The discharge of faeces into the river, is also a problem. Mercury remains present in the sediments. Coal mining has changed the course of the river, which was partially channeled by a long pipeline in the 1980s. In 2016, a section of the pipeline was replaced by a new riverbed. The rest of the pipeline, which is the Ervěnice Corridor with a length of 4.7 km (2.9 mi), is planned to be replaced in 2025–2027. The plan

375-463: The entrance to the River Ore , England, 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 mostly smooth but, dependent on how frequently they come in contact with the sea, they can have marks of contact with other rocks or other pebbles. Pebbles left above

400-522: The late 1800s and early to mid-1900s, prior to the Udden–Wentworth scale's widespread adoption, size classifications tended to group all particles larger than 2 millimeters (0.079 in) together as gravel or stones . Other scales have defined the size of a cobble slightly differently than the Udden–Wentworth; the British Standards Institution denotes a cobble as any clast ranging in diameter from 60–200 millimeters (2.4–7.9 in) while

425-637: The ocean water washes over loose rock particles. The result is a smooth, rounded appearance. The typical size range is from 2 mm to 50 mm. The colors range from translucent white to black, and include shades of yellow, brown, red and green. Some of the more plentiful pebble beaches are along the coast of the Pacific Ocean , beginning in Canada and extending down to the tip of South America in Argentina. Other pebble beaches are in northern Europe (particularly on

450-573: The river is navigable. There are only few weirs on the river and the lower course is suitable even for less experienced paddlers. Pebble A pebble is a clast of rock with a particle size of 4–64 mm (0.16–2.52 in) based on the Udden-Wentworth scale of sedimentology . Pebbles are generally considered larger than granules (2–4 mm (0.079–0.157 in) in diameter) and smaller than cobbles (64–256 mm (2.5–10.1 in) in diameter). A rock made predominantly of pebbles

475-412: The rooftops of buildings. Indoors, pebbles can be used as bookends and paperweights . Large pebbles are also 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

500-476: 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. [REDACTED] Media related to Pebbles at Wikimedia Commons Cobble (geology) A cobble (sometimes a cobblestone ) is a clast of rock defined on the Udden–Wentworth scale as having a particle size of 64–256 millimeters (2.5–10.1 in), larger than

525-408: The smoothing continues in the sea. Beach pebbles and river pebbles (also known as river rock) are distinct in their geological formation and appearance. Manufactured Pebbles-These  are made from natural stones such as marble, granite, and sandstone. Manufactured Pebbles are designed to specified sizes and forms, making them flexible for many purposes. Beach pebbles form gradually over time as

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550-420: The texture and colour. Outdoors, beach pebbles are often used for landscaping , construction and as decorative elements. Beach pebbles are often used to cover walkways and driveways, around pools, in and around plant containers, on patios and decks. Beach and river pebbles are also used to create water-smart gardens in areas where water is scarce. Small pebbles are also used to create living spaces and gardens on

575-474: The till is water-laid, finer particles like sand and pebbles may be entirely washed away, leaving a deposit of only boulders and cobbles. The term shingle beach refers to a beach covered with small- to medium-sized cobbles or pebbles (as opposed to fine sand). Glacially transported cobbles tend to share several identifying features including a tabular shape and downward diagonal striations on lateral facets. Cobble conglomerates may be alluvial in origin or

600-639: The upper course of the Bílina. There are 180 bodies of water larger than 1 ha in the basin area. The largest of them is Lake Milada with an area of 252 ha (620 acres). The big problem of the river is water pollution . In 2006, it was declared the dirtiest river in the Czech Republic. The river passes through the most industrial area of the country and, in addition to wastewater from industry, it also receives wastewater from surface mining of lignite and from households. Mercury , arsenic , organic substances and other pollutants appeared here. The main problem

625-548: Was the pollution that had accumulated from past decades. Paradoxically, in the upper course of the river, before it reaches the populated area, the water quality is at such a high level that it is suitable even for infants. Although it has been considered the dirtiest Czech river for decades, the state of pollution improved significantly in the 2010s. The main source of pollution is the chemical factory Orlen Unipetrol in Litvínov . The occurrence of Enterococcus bacteria, indicating

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