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91-603: The Cotswold Water Park is the United Kingdom's largest marl lake system, straddling the Wiltshire–Gloucestershire border, north-west of Cricklade and south of Cirencester . There are 180 lakes, spread over 42 square miles (110 km). The park is a mix of nature conservation activities, including nature reserves; recreation, including sailing, fishing, a country park and beach with water sports and play areas; rural villages; and holiday accommodation. It

182-524: A hide next to the by-pass. There are a number of seasonal ponds and a wide variety of mature natural habitats have grown up around the edges including scrub, wet woodland, marsh, and reedbed. The pits are colonised by a rich flora. In the southern site grassland plants include southern marsh-orchid , bee orchid , common fleabane , field scabious and parasitic knapweed broomrape . Marshland plants include tufted forget-me-not , water mint , pink water-speedwell , common spike-rush , amphibious bistort and

273-491: A high concentration of divalent ions and is low in dissolved organic compounds. The concentration of calcium carbonate in the lake water usually exceeds 100 mg per liter. Young marl lakes are sometimes visually stunning, with very fine suspended crystals of calcium carbonate giving the water an opaque light blue color. In Britain, marl lakes are of glacial origin and are shallow (less than 4 meters or 13 feet deep). They are associated with carbonate bedrock or bedrock of

364-594: A large part of south-eastern and a small part of western England; the river is fed by at least 50 named tributaries . The river contains over 80 islands . With its waters varying from freshwater to almost seawater, the Thames supports a variety of wildlife and has a number of adjoining Sites of Special Scientific Interest , with the largest being in the North Kent Marshes and covering 20.4 sq mi (5,289 ha). According to Mallory and Adams,

455-443: A meromictic marl lake containing a cyanobacterial thrombolitic bioherm. Marl lakes are ecologically important, but are vulnerable to damage by silting , nutrient pollution , drainage , and invasive species . To some extent, the high calcium content of marl lake water buffers it against phosphate, but the native ecological community is sensitive even to small changes in chemistry and the introduction of nutrient pollution renders

546-493: A myriad of ditches and streams. Restoration schemes for many of the active mineral workings are taking into account the vital function of these flood water storage areas, as well as creating an important habitat for a number of Local and UK Biodiversity Action Plan species (LBAP and UKBAP). The Cotswold Lakes Trust (formerly the Cotswold Water Park Trust) is a registered charity. It owns, leases or manages

637-508: A network of creeks. Lying below sea level, it is prone to flooding at exceptional tides, but has nevertheless been inhabited since Roman times. The usually quoted source of the Thames is at Thames Head (at grid reference ST980994 ). This is about 1.5 mi (2.4 km) north of the village of Kemble in southern Gloucestershire , near the town of Cirencester , in the Cotswolds . However, Seven Springs near Cheltenham , where

728-719: A number of sites within the area, and all are managed for a combination of conservation, public access, education and amenity. All these sites are important refuges and breeding grounds for several species of bats, dragonflies, damselflies, birds, mammals, fish, butterflies and other invertebrates. The Cotswold Water Park has its own Local Biodiversity Action Plan (LBAP) which targets many species or species groups, and habitat types for conservation priority. Management of all CWPT reserves incorporates requirements for these priority species and habitats, and serves to enhance and protect their sustainability. Regular surveys and monitoring are carried out by Trust staff and volunteers, and results fed into

819-432: A result of the common-ion effect . Higgins Lake, in central Michigan, US, is the only known location of freshwater oolites . These are found in a narrow band between a beach rich in clastic sediments and deeper water below wave base. Marl lakes of the upper Great Lakes region have a very low biological productivity . They typically are very sparse in macrophytes (macroscopic plants and algae), and their productivity

910-639: A summer venue for organised swimming, which is prohibited on safety grounds in a stretch centred on Central London . After the river took its present-day course, many of the banks of the Thames Estuary and the Thames Valley in London were partly covered in marshland , as was the adjoining Lower Lea Valley . Streams and rivers like the River Lea , Tyburn Brook and Bollo Brook drained into

1001-481: A through route to Cheltenham . The line ran along the southern boundary of the Edward Richardson and Phyllis Amey reserve and was closed in the early 1960s. The track bed has disappeared under arable land, but this stretch remains as a haven for wildlife. It is raised above the adjacent fields, and has been colonised by a wide range of plants native to grassland, scrub, and woodland. The grassland flora

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1092-567: Is a 2.82-hectare (7.0-acre) site near Cricklade . It is outside the Cotswold Water Park SSSI but is a separately assessed SSSI within the Cotswold Water Park. It provides protection and support for the snake's head fritillary . Example clusters include the more unusual creamy white than the dark purple (see citation reference which includes photograph of cream coloured flowerhead). Prior to the establishment of

1183-676: Is a 38.35-hectare (94.8-acre) site near Cricklade and Malmesbury . The Lower Moor Farm reserve comprises three lakes, two brooks, ponds and wetland scrapes. These are linked together by ancient hedges, woodland and meadows. The reserve was opened in May 2007 by TRH the Prince of Wales and the Duchess of Cornwall . It provides a 'gateway' to three neighbouring Wiltshire Wildlife Trust reserves: Clattinger Farm, Oaksey Moor Farm Meadow and Sandpool Farm. Upper Waterhay Meadow ( grid reference SU068932 )

1274-471: Is a landmark on the Boat Race course, while Glover's Island forms the centre of a view from Richmond Hill . Islands of historical interest include Magna Carta Island at Runnymede , Fry's Island at Reading, and Pharaoh's Island near Shepperton. In more recent times Platts Eyot at Hampton was the place where Motor Torpedo Boats (MTB)s were built, Tagg's Island near Molesey was associated with

1365-409: Is a shelter area for nest sites for various birds, and a hunting ground for Eurasian sparrowhawks . There are three reserves in the Cotswold Water Park and the adjacent area which have SSSI status attached to them. These are Clattinger Farm, Mallard Lake (Lower Moor Farm) and Upper Waterhay. Clattinger Farm ( grid reference SU017937 ) is a 60.33-hectare (149.1-acre) site near Malmesbury . It

1456-494: Is a significant area for wildlife and particularly for wintering and breeding birds. The local wildlife trusts ( Gloucestershire and Wiltshire ) are involved in partnership with the Cotswold Lakes Trust charity in working with local communities and organisations in the area. The lakes were created in the second half of the 20th century by extraction of glacial Jurassic limestone gravel , which had eroded from

1547-574: Is about half a mile (0.8 km) east of Somerford Keynes . The reserve was one of the oldest gravel workings in the upper Thames Valley. The extraction of the First Terrace Pleistocene gravels left behind an unusually deep lake, which is sealed by beds of Kellaway clay . It is a breeding site for birds including reed bunting , tufted duck , black-headed gull and great crested grebe . Water vole , water shrew and nightingale and large numbers of dragonflies are recorded for

1638-402: Is an important water source, especially in the drier months, so maintaining its quality and quantity is extremely important. Groundwater is vulnerable to surface pollution, especially in highly urbanised areas. Brooks, canals and rivers, within an area of 3,842 sq mi (9,951 km ), combine to form 38 main tributaries feeding the Thames between its source and Teddington Lock . This

1729-649: Is believed that Tamesubugus' name was derived from that of the river. Tamese was referred to as a place, not a river in the Ravenna Cosmography ( c.  AD 700 ). The river's name has always been pronounced with a simple t /t/ ; the Middle English spelling was typically Temese and the Brittonic form Tamesis . A similar spelling from 1210, "Tamisiam" (the accusative case of "Tamisia"; see Kingston upon Thames § Early history ),

1820-400: Is designed to attract wetland birds, and has several linear islands which maximise the area of available reed fringe. Bittern , reed bunting , water rail , common snipe and reed warbler are recorded as visiting this refuge. There have also been sightings of otter and water vole . There are two bird hides. The footpath to the reserve from South Cerney is subject to frequent flooding from

1911-417: Is dominated by one macrophyte species, Scirpus subterminalis (water bulrush), which is responsible for an average of 79% of the total biomass. Chara (stonewort) accounts for 12% of the biomass but limited to the most shallow, protected parts of the lake. Potamogeton (pondweed) provides most of the remaining biomass. Marl lakes often contain lakemounts. These are thought to begin with thin patches in

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2002-604: Is formed for much of its length for shipping and supplies: through the Port of London for international trade, internally along its length and by its connection to the British canal system. The river's position has put it at the centre of many events in British history, leading to it being described by John Burns as "liquid history". Two broad canals link the river to other rivers: the Kennet and Avon Canal ( Reading to Bath ) and

2093-697: Is found in Magna Carta . The Thames through Oxford is sometimes called the Isis . Historically, and especially in Victorian times, gazetteers and cartographers insisted that the entire river was correctly named the Isis from its source down to Dorchester on Thames and that only from this point, where the river meets the Thame and becomes the "Thame-isis" (supposedly subsequently abbreviated to Thames) should it be so called. Ordnance Survey maps still label

2184-884: Is gradually recovering from its financial loss, and is continuing to work toward its wide remit. [REDACTED] Media related to Cotswold Water Park at Wikimedia Commons 51°39′07″N 1°57′27″W  /  51.65194°N 1.95750°W  / 51.65194; -1.95750 Marl lake Marl lakes are found around the Great Lakes of North America, in Britain, and in other areas that were once glaciated . They support distinctive ecological communities that are vulnerable to damage from silting , nutrient pollution , drainage , and invasive species . Marl lakes typically are found in areas that were recently glaciated , and they often fill kettle depressions left behind by melting glaciers. Their most distinctive characteristic

2275-399: Is low, organic matter is scarce; this means there is little chelation of iron, which keeps primary productivity low in a vicious cycle. Phosphate , another essential nutrient, is precipitated along with carbonates, further reducing the supply of nutrients. Some mare lakes are meromictic lakes in which bottom water never mixes with surface water. Green Lake, at Fayetteville, New York , is

2366-753: Is made up of a wide range of limestone-loving plants which include field scabious , lady's bedstraw , common bird's-foot-trefoil and oxeye daisy . Various colour-forms of greater knapweed may be found as well as common twayblade . Cowslips bloom in the spring. White campion , common toadflax and mouse-ear hawkweed are also supported. Common cornsalad may also be found which is becoming increasingly rare. There are thickets of bramble , hawthorn , blackthorn , dogwood , goat willow , buckthorn and dog-rose . Woodland comprises birch and pedunculate oak . The reserve supports butterflies such as brown argus , small copper , marbled white and purple hairstreak ; some 21 species have been recorded. The scrub

2457-425: Is not within the Cotswold Water Park SSSI definitions, but a separate SSSI adjacent to the park. It is a prime example of enclosed lowland grassland and is a hay meadow of international importance. This land has been farmed traditionally without artificial fertilisers. Mallard Lake ( grid reference SU012936 ) is a 13-hectare (32-acre) site and is part of Lower Moor Farm reserve ( grid reference SU008938 ) which

2548-452: Is responsible for managing the flow of water to help prevent and mitigate flooding, and providing for navigation: the volume and speed of water downstream is managed by adjusting the sluices at each of the weirs and, at peak high water, levels are generally dissipated over preferred flood plains adjacent to the river. Occasionally, flooding of inhabited areas is unavoidable and the agency issues flood warnings. Due to stiff penalties applicable on

2639-893: Is shared by many other river names in Britain, such as the River Tamar at the border of Devon and Cornwall , several rivers named Tame in the Midlands and North Yorkshire , the Tavy on Dartmoor , the Team of the North East, the Teifi and Teme of Wales , the Teviot in the Scottish Borders and a Thames tributary, the Thame . Kenneth H. Jackson proposed that the name of

2730-558: Is sometimes called the Isis), Reading , Henley-on-Thames and Windsor . The Thames also drains the whole of Greater London . The lower reaches of the river are called the Tideway , derived from its long tidal reach up to Teddington Lock . Its tidal section includes most of its London stretch and has a rise and fall of 23 ft (7 m). From Oxford to the estuary, the Thames drops by 55 metres (180 ft). Running through some of

2821-402: Is that they deposit sediments rich in calcium carbonate . More precisely, a marl lake is a lake in which calcium carbonate makes up at least 50% of the dry weight of the inorganic fraction of the surface sediments. In some lakes, the sediments are almost pure calcium carbonate. The calcium carbonate precipitates from lake water that is alkaline, typically with a pH 8.0 or greater, and has

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2912-412: Is the source of the marl. By contrast with marl lakes of the Great Lakes region, they have a rich emergent and submerged macrophyte community. They are also home to many gastropods and crustaceans . Iron is a limiting nutrient in marl lakes, as it is practically insoluble in oxygenated, alkaline water. To be available at all, it must be chelated by organic matter. But because the primary productivity

3003-404: Is the usual tidal limit ; however, high spring tides can raise the head water level in the reach above Teddington and can occasionally reverse the river flow for a short time. In these circumstances, tidal effects can be observed upstream to the next lock beside Molesey weir , which is visible from the towpath and bridge beside Hampton Court Palace . Before Teddington Lock was built in 1810–12,

3094-735: The River Isis , is a river that flows through southern England including London . At 215 miles (346 km), it is the longest river entirely in England and the second-longest in the United Kingdom , after the River Severn . The river rises at Thames Head in Gloucestershire and flows into the North Sea near Tilbury , Essex and Gravesend , Kent, via the Thames Estuary . From the west, it flows through Oxford (where it

3185-811: The Berwyn Mountains in North Wales . About 450,000 years ago, in the most extreme Ice Age of the Pleistocene , the Anglian , the furthest southern extent of the ice sheet reached Hornchurch in east London, the Vale of St Albans, and the Finchley Gap . It dammed the river in Hertfordshire , resulting in the formation of large ice lakes, which eventually burst their banks and caused

3276-541: The British Geological Survey from the banks of the tidal River Thames contain geochemical information and fossils which provide a 10,000-year record of sea-level change. Combined, this and other studies suggest that the Thames sea-level has risen more than 30 m during the Holocene at a rate of around 5–6 mm per year from 10,000 to 6,000 years ago. The rise of sea level dramatically reduced when

3367-570: The Churn (which feeds into the Thames near Cricklade ) rises, is also sometimes quoted as the Thames' source, as this location is farthest from the mouth and adds some 14 mi (23 km) to the river's length. At Seven Springs above the source is a stone with the Latin hexameter inscription "Hic tuus o Tamesine pater septemgeminus fons", which means "Here, O Father Thames, [is] your sevenfold source". The springs at Seven Springs flow throughout

3458-763: The Cotswold Hills , and these filled naturally from rivers and streams after workings began to be exhausted in the early 1970s. Information may be found in detailed maps of locations and facilities, the Local Biodiversity Action Plan and other publications produced by the Cotswold Lakes Trust. It is that part of the Upper Thames catchment in North Wiltshire and south Gloucestershire which has been subjected to over 50 years of sand and gravel extraction. For ease of orientation,

3549-684: The Grand Union Canal (London to the Midlands). The Grand Union effectively bypassed the earlier, narrow and winding Oxford Canal which remains open as a popular scenic recreational route. Three further cross-basin canals are disused but are in various stages of reconstruction: the Thames and Severn Canal (via Stroud ), which operated until 1927 (to the west coast of England), the Wey and Arun Canal to Littlehampton , which operated until 1871 (to

3640-477: The Old Red Sandstone . Their concentration of calcium carbonate is 140 mg/L, typical of temperate limestone groundwater. The precipitation of calcium carbonate from marl lakes is a consequence of removal of carbon dioxide by photosynthesis (particularly by Chara , stonewort, which becomes encrusted with low-magnesium calcite during the summer ) or outgassing of saturated groundwater, or as

3731-489: The River Lea can be considered another boundary. Most of the local riverside was also marshland. The land was drained and became farmland; it was built on after the Industrial Revolution . Canvey Island in southern Essex (area 18.45 km , 7.12 sq mi; population 40,000 ) was once marshy, but is now a fully reclaimed island in the Thames estuary, separated from the mainland of south Essex by

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3822-662: The Royal Academy , London , in 1785. They are now on show at the River and Rowing Museum in Henley). Richard Coates suggests that while the river was as a whole called the Thames, part of it, where it was too wide to ford, was called * (p)lowonida . This gave the name to a settlement on its banks, which became known as Londinium , from the Indo-European roots * pleu- "flow" and * -nedi "river" meaning something like

3913-504: The Thames Barrier , which protects central London from flooding by storm surges . Below the barrier, the river passes Woolwich , Thamesmead , Dagenham , Erith , Purfleet , Dartford , West Thurrock , Northfleet , Tilbury and Gravesend before entering the Thames Estuary near Southend-on-Sea . The sea level in the Thames estuary is rising and the rate of rise is increasing. Sediment cores up to 10 m deep collected by

4004-549: The Thanetian stage of the late Palaeocene epoch. Until around 500,000 years ago, the Thames flowed on its existing course through what is now Oxfordshire , before turning to the north-east through Hertfordshire and East Anglia and reaching the North Sea near present-day Ipswich . At this time the river-system headwaters lay in the English West Midlands and may, at times, have received drainage from

4095-623: The Worldwide Fund for Nature (WWF) . The pools are separated by a narrow bund , and drain south towards the River Coln and the River Thames . The Court Brook is the northern boundary. The reserve is important for its wintering wildfowl, though also of interest are breeding birds, dragonflies, freshwater molluscs and plants. There are good numbers reported of tufted duck , pochard , coot, mallard and Canada geese wintering on

4186-590: The Cotswold Water Park Trust, certain elements of, or activities within the area were overseen by the Cotswold Water Park Society Limited. The Society's Chief Executive of the time, Dennis Grant, was imprisoned in 2011 for defrauding the organisation of more than £650,000, and the trust was subsequently relaunched as a registered charity working for the benefit of people and wildlife in the area. The organisation

4277-512: The Cotswold Water Park is split into three areas. The Cotswold Water Park area sits low in an historic river valley and as such is exposed to fluctuations in ground water levels. Much of the farmland in this area is made up of flood meadows which take up water from the River Thames. Many of the lakes are connected by underground culverts, allowing transfer of water between them. There is also transfer of water through ground water feeds and via

4368-736: The North Sea, and the Thames Barrier was built in the 1980s to protect London from this risk. The Nore is the sandbank that marks the mouth of the Thames Estuary , where the outflow from the Thames meets the North Sea . It is roughly halfway between Havengore Creek in Essex and Warden Point on the Isle of Sheppey in Kent. Until 1964 it marked the seaward limit of the Port of London Authority. As

4459-544: The River Thames on the Tideway include the rivers Crane , Brent , Wandle , Ravensbourne (the final part of which is called Deptford Creek ), Lea (the final part of which is called Bow Creek ), Roding (Barking Creek), Darent and Ingrebourne . In London, the water is slightly brackish with sea salt, being a mix of sea and fresh water. This part of the river is managed by the Port of London Authority . The flood threat here comes from high tides and strong winds from

4550-480: The Thames Estuary), the river is subject to tidal activity from the North Sea . Before the lock was installed, the river was tidal as far as Staines, about 16 mi (26 km) upstream. London, capital of Roman Britain , was established on two hills, now known as Cornhill and Ludgate Hill . These provided a firm base for a trading centre at the lowest possible point on the Thames. A river crossing

4641-521: The Thames as "River Thames or Isis" down to Dorchester. Since the early 20th century this distinction has been lost in common usage outside of Oxford, and some historians suggest the name Isis is nothing more than a truncation of Tamesis , the Latin name for the Thames. Sculptures titled Tamesis and Isis by Anne Seymour Damer are located on the bridge at Henley-on-Thames , Oxfordshire (the original terracotta and plaster models were exhibited at

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4732-493: The Thames is not Indo-European (and of unknown meaning), while Peter Kitson suggested that it is Indo-European but originated before the Britons and has a name indicating "muddiness" from a root *tā- , 'melt'. Early variants of the name include: Indirect evidence for the antiquity of the name "Thames" is provided by a Roman potsherd found at Oxford, bearing the inscription Tamesubugus fecit (Tamesubugus made [this]). It

4823-567: The Thames, from Middle English Temese , is derived from the Brittonic name for the river, Tamesas (from * tamēssa ), recorded in Latin as Tamesis and yielding modern Welsh Tafwys "Thames". The name element Tam may have meant "dark" and can be compared to other cognates such as Russian темно ( Proto-Slavic * tĭmĭnŭ ), Lithuanian tamsi "dark", Latvian tumsa "darkness", Sanskrit tamas and Welsh tywyll "darkness" and Middle Irish teimen "dark grey". The origin

4914-467: The adjacent Cerney Wick Brook and rising ground waters. A silt lagoon was formed by the mineral workings that created the Cleveland Lakes. This is now colonised and provides a suitable habitat for wintering and breeding birds and a refuge for reptiles and mammals. The site (Fairford Region; South Cerney Region; Coke's Pit Lake; Edward Richardson and Phyllis Amey reserve; Bryworth Lane reserve)

5005-689: The bottom sediments show deposition of marls during wet periods and sea highstands; organic-rich sediments during intervals of swampy conditions; and calcareous brown mud suggesting periods when the pond was an ephemeral lake . These cores record climate from the last interglacial , around 120,000 years ago, to nearly the present. The carbonate-rich sediments deposited by marl lakes is a mixture of clay and carbonate minerals described as marl . Marl lakes have frequently been dredged or mined for marl, often used for manufacturing Portland cement . Thames The River Thames ( / t ɛ m z / TEMZ ), known alternatively in parts as

5096-727: The case of the Colne ), and man-made distributaries such as the Longford River . Three canals intersect this stretch: the Oxford Canal , Kennet and Avon Canal and Wey Navigation . Its longest artificial secondary channel (cut), the Jubilee River , was built between Maidenhead and Windsor for flood relief and completed in 2002. The non-tidal section of the river is managed by the Environment Agency , which

5187-476: The confluence, the overall length of the Thames measured from Seven Springs, at 229 mi (369 km), is greater than the Severn's length of 220 mi (350 km). Thus, the "Churn/Thames" river may be regarded as the longest natural river in the United Kingdom. The stream from Seven Springs is joined at Coberley by a longer tributary which could further increase the length of the Thames, with its source in

5278-516: The drier parts of mainland Britain and heavily abstracted for drinking water, the Thames' discharge is low considering its length and breadth: the Severn has a discharge almost twice as large on average despite having a smaller drainage basin . In Scotland , the Tay achieves more than double the Thames' average discharge from a drainage basin that is 60% smaller. Along its course are 45 navigation locks with accompanying weirs . Its catchment area covers

5369-437: The eastern end of the reserve, and the associated reed hide allows views across the reedbed to the wooded heronry. Additional wildlife species of note for this reserve include European otter and water vole . Coke's Pit Lake ( grid reference SU027953 ) is a 3.2-hectare (7.9-acre) site. It was excavated 40 years ago, was given to the Cotswold Water Park Trust in 2002 and was declared a Local Nature Reserve (LNR) in 2003. It

5460-419: The eastern section of the Cotswold Water Park. There are four nature reserves called Whelford Pools, Edward Richardson & Phyllis Amey, Roundhouse Lake and Bryworth Lane. The Pools ( grid reference SU175995 ) and ( grid reference SU176993 ) are in the eastern section of the park, between Fairford and Lechlade . The site was purchased by the Gloucestershire Wildlife Trust in 1979 with grant aid from

5551-412: The flowing river or the wide flowing unfordable river. The river gives its name to three informal areas: the Thames Valley , a region of England around the river between Oxford and West London; the Thames Gateway ; and the greatly overlapping Thames Estuary around the tidal Thames to the east of London and including the waterway itself. Thames Valley Police is a formal body that takes its name from

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5642-533: The grounds of the National Star College at Ullenwood . The Thames flows through or alongside Ashton Keynes , Cricklade , Lechlade , Oxford , Abingdon-on-Thames , Wallingford , Goring-on-Thames and Streatley (at the Goring Gap ), Pangbourne and Whitchurch-on-Thames , Reading , Wargrave , Henley-on-Thames , Marlow , Maidenhead , Windsor and Eton , Staines-upon-Thames and Egham , Chertsey , Shepperton , Weybridge , Sunbury-on-Thames , Walton-on-Thames , Molesey and Thames Ditton . The river

5733-404: The ice melt nearly concluded over the past 4,000 years. Since the beginning of the 20th century, rates of sea level rise range from 1.22 mm per year to 2.14 mm per year. The Thames River Basin District, including the Medway catchment, covers an area of 6,229 sq mi (16,130 km ). The entire river basin is a mixture of urban and rural, with rural landscape predominating in

5824-416: The impresario Fred Karno and Eel Pie Island at Twickenham was the birthplace of the South East's R&B music scene. Westminster Abbey and the Palace of Westminster (commonly known today as the Houses of Parliament ) were built on Thorney Island , which used to be an eyot . Researchers have identified the River Thames as a discrete drainage line flowing as early as 58 million years ago, in

5915-551: The lake more hospitable to invasive species. Eventually a threshold is reached at which the lake rapidly loses its marl characteristics and flowering plants replace Chara . In Britain, only the marl lakes of the more remote parts of northern Scotland are likely to remain pristine into the near future. Many are transient or eutrophic , and at least half those in Britain have been affected by nutrient pollution. Marl ponds steadily deposit sediments that can be dated by carbon-14 . They also contain proxies for local climate. For example,

6006-443: The lake regularly. The Bryworth Lane reserve ( grid reference SP200007 ) is a 0.6-hectare (1.5-acre) site between Lechlade and Fairford to the west of the minor road to Southrop. It is a 300-yard stretch of disused railway and was purchased from the British Railways Property Board in 1990. It was part of a 25-mile-long (40 km) branch line from Oxford , which was opened in 1873. This line extended beyond Fairford to provide

6097-511: The national biodiversity reporting framework. Cleveland Lakes Reserve is made up of two of the Cotswold Water Park's larger lakes (Lake 68a/b and Lake 74) as well as the Waterhay Reedbed (Lake 68c/d). It includes 2.5 km (1.6 miles) of permissive footpath and cycleway as well as three bird viewing hides, and is an important site for breeding and wintering birds such as Eurasian coot , great crested grebe , gadwall , tufted duck , little egret and grey heron . New reedbeds have been created at

6188-426: The non-tidal river, which is a drinking water source before treatment, sanitary sewer overflow from the many sewage treatment plants covering the upper Thames basin should be rare in the non-tidal Thames. However, storm sewage overflows are still common in almost all the main tributaries of the Thames despite claims by Thames Water to the contrary. Below Teddington Lock (about 55 mi or 89 km upstream of

6279-401: The northern pit since 1972. The pits were created by the extraction of Oolitic gravel , the lakes are bedded by Oxford clay . The depth of the water fluctuates throughout the year and the pools are unusually shallow for water park pits. A nature trail around the southern site allows viewing of the different habitats. There is no public access to the northern pit but wildfowl may be viewed from

6370-420: The original kettle ice, which were colonized by Najas , Potamogeton , and Chara . These locally enhanced the sediment deposition rate to build up the lakemounts to near the lake surface. The lakes are often surrounded by beachrock composed of cemented pisoliths (calcite concretions) and gastropod shells. The shallow beachrock slopes are inhabited by Chara. British marl lakes are dominated by Chara , which

6461-401: The ponds. Roundhouse lake is a 17-hectare (42-acre) site. It is a large open body of water and supports a large number of wintering wildfowl, including wigeon , red-crested pochard , goldeneye , pochard and tufted duck . Great crested grebe and little grebe are frequent visitors and kingfisher sightings reported. Birds may be viewed from a hide. Eurasian otters are reported to visit

6552-433: The rare greater tussock-sedge . A relatively large number of species of dragonfly and damselfly are recorded, as well as good populations of southern aeshna , common sympetrum and common blue damselfly . The emperor dragonfly visits occasionally. Patches of nettle and thistle attract many butterflies and teasel attracts brimstones and encourages goldfinches . The site is of interest to birdwatchers throughout

6643-637: The river passes Pimlico and Vauxhall , and then forms one of the principal axes of the city, from the Palace of Westminster to the Tower of London . At this point, it historically formed the southern boundary of the medieval city, with Southwark , on the opposite bank, then being part of Surrey . Beyond central London, the river passes Bermondsey , Wapping , Shadwell , Limehouse , Rotherhithe , Millwall , Deptford , Greenwich , Cubitt Town , Blackwall , New Charlton and Silvertown , before flowing through

6734-439: The river was tidal at peak spring tides as far as Staines upon Thames . In descending order, non-related tributaries of the non-tidal Thames, with river status, are the Churn , Leach , Cole , Ray , Coln , Windrush , Evenlode , Cherwell , Ock , Thame , Pang , Kennet , Loddon , Colne , Wey and Mole . In addition, there are occasional backwaters and artificial cuts that form islands, distributaries (most numerous in

6825-596: The river, covering three counties . In non-administrative use, the river's name is used in those of Thames Valley University , Thames Water , Thames Television , publishing company Thames & Hudson , Thameslink (north–south rail service passing through central London ) and South Thames College . An example of its use in the names of historic entities is the Thames Ironworks and Shipbuilding Company . Marks of human activity, in some cases dating back to Pre-Roman Britain , are visible at various points along

6916-456: The river, while some islands, e.g. Thorney Island , formed over the ages. The northern tip of the ancient parish of Lambeth , for example, was marshland known as Lambeth Marshe , but it was drained in the 18th century; the street names Lower Marsh and Upper Marsh preserve a memory. Until the middle of the Victorian era, malaria was commonplace beside the River Thames, even in London, and

7007-519: The river. These include a variety of structures connected with use of the river, such as navigations, bridges and watermills , as well as prehistoric burial mounds . The lower Thames in the Roman era was a shallow waterway winding through marshes. But centuries of human intervention have transformed it into a deep tidal canal flowing between 200 miles of solid walls; these defend a floodplain where 1.5 million people work and live. A major maritime route

7098-611: The sandbank was a major hazard for shipping coming in and out of London, in 1732 it received the world's first lightship . This became a major landmark, and was used as an assembly point for shipping. Today it is marked by Sea Reach No. 1 Buoy. The River Thames contains over 80 islands ranging from the large estuarial marshlands of the Isle of Sheppey and Canvey Island to small tree-covered islets like Rose Isle in Oxfordshire and Headpile Eyot in Berkshire. They are found all

7189-590: The sediments of Pretty Lake in Indiana , USA, contain chlorophyll degradation products from which its history of biological productivity can be estimated. This record shows a peak in productivity during the Boreal Age (9 to 7.6 thousand years ago) and another peak at about 6000 years ago. Wallywash Great Pond in Jamaica is an unusual tropical marl lake whose sediments also record climate fluctuations. Cores of

7280-594: The site is the only known one in Gloucestershire for the tiny 'pea mussel'. The Edward Richardson and Phyllis Amey reserve ( grid reference SP215007 ) is an 11.1-hectare (27-acre) site. There is a 5.4-hectare (13-acre) gravel pit south of the by-pass and a 5.7-hectare (14-acre) gravel pit north of the by-pass. The site is named after the late site manager and the sister of the former Amey Roadstone Corporation chairman. The two pits are leased from ARC Properties Ltd. The southern pit has been leased since 1970 and

7371-428: The site. Elmlea Meadows is a Site of Special Scientific Interest . The designation recognised the nationally scarce downy-fruited sedge ( Carex tomentosa ) and snake's head fritillary . The old railway line (previously Midland and South Western Junction Railway ) is a wildlife corridor between South Cerney and Cricklade. Shorncote Reedbed is at the north-east corner, towards South Cerney (Lakes 84 and 85). It

7462-509: The site. Also present are great crested grebe, mute swan and shoveler . Red-crested pochard and ruddy duck are occasional visitors. The site is a breeding area for tufted duck and great crested grebe along with kingfisher , reed bunting and sedge warbler . There are two main lakes and three small pools frequented by dragonflies. The emperor dragonfly , migrant hawker , black-tailed skimmer and red-eyed damselfly are amongst other breeding species. Freshwater molluscs are represented and

7553-541: The south coast), and the Wilts & Berks Canal . Rowing and sailing clubs are common along the Thames, which is navigable to such vessels. Kayaking and canoeing also take place. Major annual events include the Henley Royal Regatta and the Boat Race , while the Thames has been used during two Summer Olympic Games : 1908 ( rowing ) and 1948 ( rowing and canoeing ). Safe headwaters and reaches are

7644-705: The way from Fiddler's Island in Oxfordshire to the Isle of Sheppey in Kent. Some of the largest inland islands, for example Formosa Island near Cookham and Andersey Island at Abingdon, were created naturally when the course of the river divided into separate streams. In the Oxford area the river splits into several streams across the floodplain ( Seacourt Stream , Castle Mill Stream , Bulstake Stream and others), creating several islands ( Fiddler's Island , Osney and others). Desborough Island , Ham Island at Old Windsor and Penton Hook Island were artificially created by lock cuts and navigation channels. Chiswick Eyot

7735-412: The western part. The area is among the driest in the United Kingdom. Water resources consist of groundwater from aquifers and water taken from the Thames and its tributaries, much of it stored in large bank-side reservoirs . The Thames itself provides two-thirds of London's drinking water, while groundwater supplies about 40 per cent of public water supplies in the overall catchment area. Groundwater

7826-580: The year, while those at Thames Head are seasonal (a winterbourne ). With a length of 215 mi (346 km), the Thames is the longest river entirely in England. (The longest river in the United Kingdom, the Severn , flows partly in Wales .) However, as the River Churn, sourced at Seven Springs, is 14 mi (23 km) longer than the section of the Thames from its traditional source at Thames Head to

7917-577: The year. Resident birds include common moorhens , Eurasian coots , mallards , great crested grebes and tufted ducks and herons fish the northern lake. Scrub and willow carr provide nesting sites for sedge warblers , whitethroats , Eurasian wrens and common chaffinches . Common house martins and common swifts feed on the abundant insect life. Common kingfishers breed in the northern area. In winter brambling , fieldfare , Eurasian wigeon , gadwall , pochard and Eurasian teal may be sighted. Great crested newts , frogs and toads breed in

8008-479: Was built at the site of London Bridge . London Bridge is now used as the basis for published tide tables giving the times of high tide . High tide reaches Putney about 30 minutes later than London Bridge, and Teddington about an hour later. The tidal stretch of the river is known as "the Tideway ". Tide tables are published by the Port of London Authority and are available online. Times of high and low tides are also posted on Twitter. The principal tributaries of

8099-463: Was frequently lethal. Some cases continued to occur into the early 20th century. Draining of the marshes helped with its eradication, but the causes are complex and unclear. The East End of London , also known simply as the East End , was the area of London east of the medieval walled City of London and north of the River Thames, although it is not defined by universally accepted formal boundaries;

8190-506: Was listed in the Cotswold District Local Plan 2001–2011 as a Key Wildlife Site (KWS). Only a few of the lakes are accessible for public use. It is a 135-hectare (330-acre) site of Site of Special Scientific Interest notified in 1994. In January 2021, further areas were given SSSI status and a consultation begun on further extending the area covered. The Gloucestershire Wildlife Trust activities are based in

8281-617: Was subject to minor redefining and widening of the main channel around Oxford, Abingdon and Marlow before 1850, when further cuts to ease navigation reduced distances further. Molesey faces Hampton , and in Greater London the Thames passes Hampton Court Palace , Surbiton , Kingston upon Thames , Teddington , Twickenham , Richmond (with a famous view of the Thames from Richmond Hill), Syon House , Kew , Brentford , Chiswick , Barnes , Hammersmith , Fulham , Putney , Wandsworth , Battersea and Chelsea . In central London ,

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