103-635: The Lea Valley , the valley of the River Lea , has been used as a transport corridor, a source of sand and gravel, an industrial area, a water supply for London , and a recreational area. The London 2012 Summer Olympics were based in Stratford , in the Lower Lea Valley . It is important for London's water supply, as the source of the water transported by the New River aqueduct, but also as
206-555: A Ford components (later Visteon ) plant and Johnson Matthey . Much industry has now gone, replaced by warehousing and retail parks. North of Cheshunt the Lea Valley, particularly around Nazeing , is associated with market gardening , nurseries and garden centres . The industry once dominated the area from Ponders End , north through Enfield Lock , Waltham Cross and Cheshunt, to Wormley , Turnford and Nazeing, and spawned industries such as Pan Britannica Industries . In
309-523: A distinctively bow-shaped, three-arched, bridge to be built over the River Lea ( The like of which had not been seen before ), at Bow, the first bridge over the lower Lea. The lower Lea was at that time a wide, tidal and unchannelled river, so the construction of the bridge allowed a far greater degree of social and economic integration between Essex on one side and Middlesex (including the City of London) on
412-537: A "Chiltern" ice advance is not now accepted.) It was later suggested that the section of the supposed "Middlesex loopway" going north-east beyond the Finchley depression "may well have originated as a ... south-bank tributary of an earlier axial line of drainage even though it later served for the diverted Thames". This "south-bank tributary" would have been the proto-Mole-Wey. In his 1938 paper, Wooldridge suggested that deposits which do exist in this eastern section of
515-492: A correspondent to the Gentleman's Magazine in 1823, in which he claimed to have heard from a woman who was a child in the reign of Charles II (r. 1660–1685) and had the lyrics: Finchley Gap The Finchley Gap (or "Finchley depression") is a location centred on Church End, Finchley , in north London , England . As a topographical feature approximately eight kilometres wide, lying between higher ground to
618-495: A major source of drinking water for London. An artificial waterway known as the New River , opened in 1613, abstracts clean water away from the upper stretch of the river near Hertford for drinking. The Lea's origin in the Chilterns contributes to the extreme hardness (high mineral content) of London tap water. The name of the River Lea was first recorded in the 9th century, although is believed to be much older. Spellings from
721-830: A shipyard which straddled either side of the Lea at its confluence with the Thames. The 2012 Olympics was focused in the Queen Elizabeth Olympic Park on the banks of the Lea, and its main Stadium, on an island between two branches of the river, is now home to West Ham United. The Lee Valley White Water Centre in Hertfordshire is another sporting legacy of the games. Various versions of the nursery rhyme London Bridge Is Falling Down make reference to Bow Bridge. The oldest known version could be that recalled by
824-559: A slightly lower altitude, was also deposited by an ancestral Mole-Wey, but at a later date (which could have been around 1.75 million years ago). At those times, the topography of the country around today's Finchley Gap would have been very different, because the Pebble Gravel was laid down in a valley bottom, whereas today it occupies the highest ground. The relief has been inverted. But, in 1979, P.L. Gibbard mapped younger deposits, known as Dollis Hill Gravel and named after one of
927-606: A stone causeway on the Roman road to Colchester was supplemented by bridge in 1100. In 1745 the valley was crossed at Clapton by Lea Bridge . In 1810 an iron bridge was built linking East India Dock Road . In the late 1920s the Lea Valley Viaduct , carrying the North Circular Road , was built to a design by Owen Williams . This was replaced in the 1980s. The valley of the Lea formed a route followed by
1030-654: Is also used in geology, archaeology, etc. to refer to the Lea Valley . The term River Lea is Cockney rhyming slang for tea. The line of the Lea, and its major tributary, the Stort, has long been used as a political boundary. In the Iron Age the Lea and Stort valleys formed a hotly contested frontier zone between the Catuvellauni to the west and the eastern Trinovantes . The two rivers are assumed to have been
1133-401: Is capped over wide areas, at altitudes ranging from about 150m to 130m, by a fairly thin (average 3 metres) layer of sand and gravel known as Pebble Gravel (or, in places, Stanmore Gravel). Although flint is the main component of this gravel, it has been known since the late nineteenth century that it also contains in places a notable quantity of chert derived from Lower Greensand Beds in
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#17327721259551236-680: Is derived). The River Lea flows through the old brewing and malting centre of Ware , and consequently transport by water was for many years a significant industry based there. Barley was transported into Ware, and malt out via the river, in particular to London. Bargemen born in Ware were given the "freedom of the River Thames" — avoiding the requirement of paying lock dues — as a result of their transport of fresh water and food to London during The Great Plague of 1665–66. A local legend says that dead bodies were brought out of London at that time via
1339-827: Is in the East of England and Greater London . It originates in Bedfordshire , in the Chiltern Hills , and flows southeast through Hertfordshire , along the Essex border and into Greater London , to meet the River Thames at Bow Creek . It is one of the largest rivers in London and the easternmost major tributary of the Thames. The river's significance as a major east–west barrier and boundary has tended to obscure its importance as north–south trade route. Below Hertford
1442-525: Is much greater, and the communities on either side better integrated as a result. The source of the Lea is usually said to be at Well Head inside Waulud's Bank , a neolithic henge at Leagrave Common in Luton , Bedfordshire , although just downstream the river is joined by Houghton Brook , a stream that starts 2 miles (3 km) further west in Houghton Regis . After passing through Luton,
1545-576: Is the Dollis Brook ), and Mutton Brook . A similar process led to the creation of the south-flowing lower section of the River Lea , which was able to establish a link to the diverted Thames to the east of Hampstead Heath. Drainage from the glacial till left by the ice lobe to the north-east of the Finchley Gap carved routes which led to the River Lea, thus initiating the drainage network of Bounds Green Brook and Pymmes Brook . Thus, during
1648-536: The Anglo-Saxon period include Lig(e)an in 880 and Lygan in 895, and in the early medieval period it is usually Luye or Leye . It seems to be derived from a Celtic (brythonic) root lug -meaning 'bright or light' which is also the derivation of a name for a deity, so the meaning may be 'bright river' or 'river dedicated to the god Lugus '. A simpler derivation may well be the Brythonic word cognate with
1751-513: The Battle of Bow Bridge , the Royalists headed for Colchester and were besieged there . During WWI, parts of London on either side of the Lea were badly hit by German Army and Navy airship raids. It is believed the crews mistook the extensive reservoir chain for the Thames and released their bombs on what they took to be central London. The ecological, landscape and recreational importance of
1854-579: The Claygate Beds , is also found. In certain areas of relatively limited extent, such as on the higher parts of Harrow on the Hill , Hampstead and Highgate , the London Clay and Claygate Beds are overlain by sandy Eocene Bagshot Beds . All these formations are overlain in several areas by much younger Pleistocene formations, as explained below. From 1938 until the 1960s, it was supposed that
1957-620: The Congreve Rocket Factory on the site of Stratford Langthorne Abbey . Improvements were made to the river from 1424, with tolls being levied to compensate the landowners, and in 1571, there were riots after the extension of the River was promoted in a private bill presented to the House of Commons . By 1577, the first lock was established at Waltham Abbey and the river began to be actively managed for navigation. The New River
2060-588: The Middle Lea . During the Middle Ages , Temple Mills , Abbey Mills , Old Ford and Bow were the sites of water mills (mainly in ecclesiastic ownership) that supplied flour to the bakers of Stratforde-atte-Bow, and hence bread to the City. It was the channels created for these mills that caused the Bow Back Rivers to be cut through the former Roman stone causeway at Stratford (from which the name
2163-647: The New River and Lee Navigation , and roads including the Roman Ermine Street , the Hertford Road (A1010) and the later Great Cambridge Road (A10) and A1055. The valley is also followed by two routes of what became the Great Eastern Railway and had important marshalling yards and locomotive works at Temple Mills . Much early industrialisation was a result of the availability of water power for numerous mills. These include
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#17327721259552266-556: The North Sea . The lower part of today's Lea valley was formed during the Anglian glaciation. During that period, ice from the north of England advanced at least as far south as Watford, Finchley and Chingford . As a result, the River Thames was diverted to a more southerly route, broadly along the line of its current course. As the ice retreated, the lower part of the River Lea was formed. It flowed almost directly north–south into
2369-475: The Prescott Channel to maintain water levels on the Lea, within the park at a depth of 2 metres (7 ft). This allowed access to the site by 350–tonne barges with the aim that at least half of the material required for construction could be delivered or removed by water. In January 2024, the River Lea burst its banks as Hackney Wick residents tell of 'knee-high' flood water. Millfields Park on
2472-544: The Queen Elizabeth Olympic Park . In that park, and just to the south of it, the river's course splits, running almost entirely in man-made channels, the Bow Back Rivers . These channels were once much more numerous and originally created to power water mills including, at the southern end, the restored tidal mill called Three Mills . The area around the Bow Back Rivers subsequently became a thriving industrial zone. Around Bow Creek , major industry prevailed, including
2575-614: The River Lee Diversion . These reservoirs come to an end on the boundaries of the London Boroughs of Haringey and Hackney and form part of a broad undeveloped green space, a mile (800 m) wide in places, which extends deep into London. On Hackney's northern edge, the Lea shifts to a south-south-easterly direction, the reservoirs end, but the broad green corridor continues as the river passes through Walthamstow Marshes , Leyton Marshes , Hackney Marshes and
2678-619: The River Thames once flowed through the Gap, along the line of a " Middlesex loopway" running from somewhere around Harefield to the Hoddesdon - Ware area. This supposition was later shown to be erroneous. Prior to the Anglian glaciation, the "proto-Mole-Wey"river, a then south bank tributary of the "proto-Thames", flowed northwards from the Weald , through Richmond and the Finchley Gap, to
2781-490: The River Thames . The Lee Navigation was established by Acts of Parliament and only that spelling is used in this context. The Lee Valley Regional Park Authority also uses this spelling for leisure facilities. However, the spelling Lea is used for road names, locations and other infrastructure in the capital, such as Leamouth , Lea Bridge , the Lea Valley Walk and the Lea Valley lines (railway). This spelling
2884-534: The Thames Ironworks , Bromley-by-Bow Gasworks and West Ham Power Station . In the 1960s and 1970s, changing economic conditions led to a steep decline and deindustrialisation along this section of the Lea. The river was historically tidal as far north as Hackney Wick , but now the tide is held back by the Bow Locks between Bromley-by-Bow and West Ham. Although watercraft can follow the Lea down to
2987-550: The Waltham Abbey Royal Gunpowder Mills (originally a fulling mill but already producing gunpowder by 1665), the 19th century Royal Small Arms Factory at Enfield and Wright's Flour Mill (Greater London's last surviving working mill) at Ponders End . Further south at Bow is the Three Mills tidal complex. In the 18th century Bow porcelain factory flourished. In the 19th century
3090-496: The ecosystem , but also leads to de-oxygenation of the water. Dumping, litter and microplastics are a major problem on the Lea with much of this waste arriving in the river in sewage. In April 2021, Hackney Council wrote to the Environment Agency calling for action to address sewage discharge and pollution in the river. In November 2021, local volunteers stated they were removing 100kg of plastic pollution from
3193-457: The "Middlesex loopway" (known today as Dollis Hill Gravel) were "possible" gravels laid down by the Thames. (This too has since been shown to be a false assumption.) The almost complete absence of any gravels which might have been deposited by the diverted Thames in the western section of the "Middlesex loopway" (between Harefield and the Finchley depression) was judged by Wooldridge to be a "slight" consideration, bearing in mind "how extensively
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3296-487: The "Middlesex loopway", shown on current geological maps as "Dollis Hill Gravel", have been demonstrated to be deposits of the proto-Mole-Wey river, not of the River Thames. The "Middlesex loopway" hypothesis has thus been definitively rejected. The dissected plateau which lies to the south-east of the Vale of St Albans and north-west of the Finchley Gap, stretching from Bushey Heath , to Potters Bar , Northaw and beyond,
3399-558: The 1930s the valley contained the largest concentration of greenhouses in the world. Stamp writing in 1948 described how glasshouses, originally established on the 'warm brickearth soils' of Tottenham and Edmonton in the 1880s, had been progressively driven north into the often poorer soils further north by the growth of London. At the same time the growth of industry had intensified the lack of winter sunshine. Today, in most parts south of Cheshunt greenhouses have been replaced by residential areas. The Lee Valley Park occupies large areas of
3502-464: The 20th century the combination of transport, wide expanses of flat land and electricity from riverside and canal-side plants such as Brimsdown , Hackney , Bow and West Ham led to expansion of industries including for example Enfield Rolling Mills and Enfield Cables , Thorn Electrical Industries , Belling, Glover and Main , MK Electric , Gestetner , JAP Industries , Ferguson Electronics , Hotpoint , Lesney (original makers of Matchbox toys ),
3605-573: The Finchey Gap, and its place in the history of academic research, makes it one of the most interesting topographical features of the London area. The principal geological formation in the Finchley Gap region, as in much of the London Basin , is Eocene London Clay . This is mostly a stiff blue-brown clay, over 100 metres thick. In parts of this region, a relatively thin, upper part of the London Clay formation, sandier in content and known as
3708-429: The Finchley Gap, in the sense of being an area of lower ground lying between higher ground on either side (at Mill Hill and Hampstead Heath, both at altitudes of over 120 metres today), must have existed by the time those highest deposits of Dollis Hill Gravel were laid down. The highest Dollis Hill Gravel deposits at 100 metres have not been dated precisely. But deposits of Gerrards Cross Gravel (which were laid down by
3811-437: The Finchley depression. Instead, it was established that the river stayed on a course north-eastward through the Vale of St Albans until it was diverted, by the Anglian ice advance, approximately 450,000 years ago. The river was diverted to a more southerly route, roughly along the line of that followed by today's river. Furthermore, by the 1980s, evidence for a "Chiltern Drift" glaciation, which Wooldridge believed had diverted
3914-407: The Finchley depression. The Thames was diverted to a more southerly course, through Richmond, beyond the furthest reach of the Anglian ice sheet. No deposits which were unambiguously of Thames origin were ever found along the line of the "Middlesex loopway". In the 1970s, detailed study of deposits in the Vale of St Albans led researchers to the conclusion that the River Thames never flowed through
4017-482: The Hoddesdon-Ware area. There, it joined the proto-Thames (which at that time was flowing north-eastwards, through the Vale of St Albans ). About 450,000 years ago, a lobe of the Anglian ice sheet advanced up the valley of the proto-Mole-Wey at least as far south as the Finchley Gap. There, the ice left glacial drift which today is up to 18 metres in thickness. Another lobe of the Anglian ice sheet moved up
4120-454: The Lea at Hackney, is the reputed site of a victory of Aescwine of Essex over Octa of Kent in 527, which allowed Aescwine to become the first King of Essex . However, the historicity of these events and the very existence of Aescwine are disputed. Somewhere between 878 and 890, the Treaty of Alfred and Guthrum was drawn up that amongst other things used the course of the Lea to define
4223-504: The Lea flows on a wide floodplain , which becomes an increasingly urban transport corridor as it enters Greater London. Many of the upper sections have been exploited for sand, gravel or brickearth, and are now part of the Lee Valley Park . From Hoddesdon a more or less continuous ribbon development runs south to the west of the river, running through Wormley , Broxbourne , Cheshunt and Waltham Cross to Freezy Water . To
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4326-599: The London Borough of Enfield, the ground slopes from an altitude of only about 25 metres at the Ridge Avenue library to about 15 metres at the foot of Kings Head Hill, some five kilometres to the east. It then rises to an altitude of 85 metres on the summit of Pole Hill , barely a further one kilometre to the east. Across that five kilometres of valley floor, the ground is mostly covered by river terrace deposits of decreasing altitude and age, thus demonstrating that
4429-428: The London Clay surface has been dissected and lowered here". The second stage in the diversion of the Thames supposedly took place "a long period of time" after the first stage. During an ice advance referred to by Wooldridge (1938) as that of the "Eastern Drift" (and today known as that of the Anglian stage ), lobes of the ice sheet advanced from the north-east along the Vale of St Albans towards Watford, and towards
4532-466: The Lower Lea every month. Water extraction, for drinking water, farming and industry, has led to a reduction in river flow impacting wildlife and concentrating the pollutants present in the remaining river water. Projects such as that led by Thames21 installing reedbeds help to remove pollutants whilst oxygenating the water, as well as creating habitat for the likes of water voles and improving
4635-454: The Thames from the Vale of St Albans into its supposed intermediate route through the Finchley depression, had been seriously challenged. And, although the pre-Anglian history of glaciations in Britain is known to be complex, and is still the subject of varying interpretations, the hypothesis of a pre-Anglian "Chiltern" glaciation is today nowhere supported. Gravels in the eastern section of
4738-550: The Thames, it is generally more practical to follow the Limehouse Cut (which meets the Lea at Bow Locks) down to Limehouse Basin , and use the Limehouse Basin Lock to join the Thames. The communities on the west side of the lower Lea include Hackney , Bow and Bromley-by-Bow . On the east side, they include southern parts of Walthamstow , then Leyton , Stratford and West Ham . The last few miles of
4841-613: The Vale of St Albans itself and was heading to the North Sea further south, in the Colchester area. In 1938, it was suggested by the British geomorphologist S.W. Wooldridge that the River Thames had been diverted from its course through the Vale of St Albans to roughly its present, more southerly, course, in two stages. This two-stage hypothesis was presented again over the subsequent three decades in several publications. In
4944-538: The Vale of St Albans to Watford. These hypotheses have since been confirmed by much subsequent research, some of which is cited in this article. In fact, in the Early Pleistocene, the Thames flowed somewhat north-west of, but parallel to, today's Vale of St Albans, then continued towards North Norfolk on its journey to the North Sea . By the Middle Pleistocene, the Thames was flowing through
5047-440: The Vale of St Albans was diverted southwards from around Hoddesdon by an advancing Anglian ice sheet, this could only have been for a brief (geologically speaking) period, because the ice then progressed further to the south and caused the above-mentioned complete diversion of the Thames to its more southerly course of today. In addition, it is clear that the River Lea alone has been powerful enough to cause significant erosion below
5150-670: The Vale of St Albans, thus diverting the Thames southwards. When this happened, the proto-Mole-Wey was cut off at Richmond . The Finchley Gap now lies on the watershed of the catchment areas of the Rivers Brent and Lea, both south-flowing tributaries of the Thames. It has been known since the nineteenth century that an ice sheet once descended from the north of England as far as north London and left behind extensive spreads of till and other glacial deposits. Lobes of this ice sheet extended up two valleys, oriented south-west to north-east, reaching as far south as Watford and Finchley. In
5253-468: The Weald. It was suggested early on that this "pointed to the former existence of streams from that area". S.W. Wooldridge later suggested that it was in fact "a river of major dimensions" (which) "entered from the south" that was responsible for transporting much of this chert to areas which are now north of the River Thames. It was clear from the broad course which Wooldridge plotted for this river that it
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#17327721259555356-414: The above summary is accurate as far as it goes, but in reality the processes of glaciation and river diversion were more complex than in this summary - for example, four separate ice advances of the Anglian glaciation in this area have been identified.) Prior to the Anglian glaciation, a "proto-Mole-Wey" river was flowing northwards from the Weald and North Downs, through the " Finchley depression ", to join
5459-475: The accessibility of the area and contributing to the ribbon development that made the character of the west side of the valley much more developed than the east. Just after Hertford, the river passes the medieval river port of Ware and the Hertfordshire bank soon becomes entirely developed. On the west bank the river passes Hoddesdon , Broxbourne and Cheshunt in Hertfordshire; then Enfield , Edmonton , Tottenham and Tottenham Marshes in north London. On
5562-464: The aesthetics of the man-made concrete sections of the canalised river. In their early days, Tottenham Hotspur played their games at Tottenham Marshes on the Middle Lea while Leyton Orient have had a number of home grounds in the Lower Lea Valley , with both having their current grounds within a mile of the river. West Ham United was established as the works team of the Thames Ironworks ,
5665-613: The altitude of river-borne Pleistocene deposits is normally closely correlated with their age. So it follows from all this that the Finchley Gap was created by the proto-Mole-Wey river, which was, and had been for some time before the Gap evolved, a south-bank tributary of the proto-Thames. It is also possible to deduce, though more cautiously, that the land where the Gap is now found first became an area of lower ground lying between higher ground on either side at least one million years ago. The only Pleistocene glaciation in Britain which produced an ice sheet that reached as far south as London
5768-442: The area that year, ahead of the 2012 Olympic Games . The river is threatened by pollution, with sewage frequently discharged into the river as well as less common events causing major damage, such as an oil leak in 2018, or the toxic runoff from a warehouse fire in 2019. The sewage pollution, as well as that of fertiliser washed in from agricultural fields causes eutrophication , an excess of nutrients, which not only unbalances
5871-637: The border between the Danes and the English. In 894, a force of Danes sailed up the river to Hertford, and in about 895 they built a fortified camp, in the higher reaches of the Lea, about 20 miles (32.2 km) north of London. Alfred the Great saw an opportunity to defeat the Danes and dug a new channel to lower the level of the river, leaving the Danes stranded. In 1216, during the First Barons' War ,
5974-497: The boundaries of London's parliamentary constituencies, the Boundary Commission treats the Thames and Lea as London's major internal barriers. It will not allow a new or altered constituency that spans either river, viewing such a construct as artificial and not reflective of local communities or identities. They have compromised on this further south, on the lower Lea, where the quality and quantity of cross-river links
6077-639: The boundary between the core territory of the Kingdom of the East Saxons and its Middle Saxon Province . The whole of the Lea was subsequently used as the boundary between English-ruled territory to the west and the Danelaw , established in the late 9th century, to the east. From around the ninth or tenth century, and the establishment of counties in this part of England, the Lea-Stort line has formed
6180-487: The early days, distance from London for noxious industries and the availability of water power. Later factors included cheap electrical power from Brimsdown and large expanses of flat land. In earlier centuries the river Lea and its marshland formed a natural boundary between the historic areas of Middlesex and Essex , some 2 km wide and 20 km long. The river was crossed at several points by fords or ferries, which were eventually replaced by bridges. At Stratford
6283-476: The early twentieth century, it was suggested that the River Thames, after descending through Oxfordshire , entering the London Basin near Goring and running north-east from there, continued in that direction prior to the ice advance, past Watford and along the line of the Vale of St Albans. It was concluded that the Thames must have been diverted to its more southerly course of today by the ice advance up
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#17327721259556386-521: The east of, and slightly lower than, the lowest gravel deposits left by the proto-Mole-Wey (shown on BGS maps as "Dollis Hill Gravel"). But the River Lea has clearly moved eastwards since the Boyn Hill terraces were laid down. In fact, the lower Lea Valley has been noted for the striking width of its valley floor, especially the section from Wormley down to Tottenham , as well as for the relative steepness of parts of its eastern slope. For example, in
6489-583: The eastern side the river passes Waltham Abbey on the largely rural Essex bank, and then Chingford and Walthamstow in east London. South of Hertford, the river is lined by lakes; to the north these are primarily flooded former gravel pits but in London they are reservoirs: the 13 reservoirs of the Lee Valley Reservoir Chain , fed by the branches of the river known as the River Lee Flood Relief Channel and
6592-507: The first stage, it was assumed that "local or Chiltern ice" advanced from the north-west across the line of the Thames "in the neighbourhood of St. Albans", thus blocking the river and forcing it to find a more southerly course. It was suggested that the Thames thus turned roughly eastwards from around Harefield, passed north of Harrow on the Hill, went through the Finchley depression, and then continued north-eastwards "to rejoin its former line near Ware". (As explained below, this hypothesis of
6695-459: The future Louis VIII of France besieged Hertford Castle for a month, leading to its surrender. He only held the castle for a relatively short time as he lost the war soon after. In 1648 during the second English Civil War a Royalist force crossed the Thames from Greenwich and hoped to cross Bow Bridge, over the Lea and into Essex. After inconclusive clashes with the Tower Hamlets Militia and other Parliamentarian forces, an engagement known as
6798-400: The historic boundary between Essex to the east and Hertfordshire and Middlesex to the west. Within London the river is always used as a boundary between London Boroughs - which in turn inherit more ancient county and parish boundaries which also used the Lea as a boundary. Between 1889 and 1965, the lower Lea was the eastern boundary of the County of London with Essex . When reviewing
6901-401: The latter part of the Anglian stage and subsequently, the topography of the Finchley Gap area was transformed. From having been a section of valley floor into which drainage flowed (at the time of the proto-Mole-Wey river), it became a relatively elevated area of land (on glacial till) from which drainage flows into nearby streams. But it is still a "gap" or "depression" today in the sense that it
7004-443: The locality of the Finchley Gap, the ice left glacial deposits which today are up to 18 metres in thickness. And meltwater which poured from the front and sides of the Finchley Gap ice lobe carved routes southwards, west of Hampstead Heath, towards the newly-diverted Thames. This process thus reversed the previous direction of drainage and initiated today's drainage network of the River Brent (which in its upper section, north of Hendon,
7107-416: The location for the Lee Valley Reservoir Chain , stretching from Enfield through Tottenham and Walthamstow . The catchment area of the River Lea is located in the central part of the London Basin , on that basin's northern flank. The main underlying geological formation of the upper part of the Lea catchment, north of Hoddesdon , is Cretaceous Chalk . The main underlying geological formation of
7210-510: The locations where this deposit is found, which were also laid down by the proto-Mole-Wey river. These deposits are found at what is today the Finchley Gap, and to the north-east and south-west of it. Dollis Hill Gravel is found, for example, south-west of the Gap at Hendon and Horsenden Hill , and north-east of the Gap over wide areas from Southgate to Goff's Oak . Today, the highest of those deposits rest at an altitude of around 100 metres (for example at Muswell Hill and Cockfosters ). So
7313-451: The lower Lea became an important area for the manufacture of chemicals, in part based on the supply of by-products such as sulphur and ammonia from the Gas Light and Coke Company 's works at Bow Common. Other industries included Bryant and May , Berger Paints, Stratford Railway Works and confectionery manufacturer Clarnico (later Trebor ). Where the river meets the Thames were the Orchard House Yard and Thames Ironworks shipyards. In
7416-431: The lower River Lea has migrated eastwards since it was formed some 400,000 years ago. Some authors have proposed that the notable width of the lower Lea Valley indicates that it was once occupied by a larger and more powerful river, namely the proto-Thames. However, this hypothesis is not universally supported. In any case, even if all or some of the water being conveyed by the proto-Thames as it flowed north-east through
7519-565: The lower part of the Lea catchment, south of Hoddesdon, is Eocene London Clay . However, large areas of these formations are overlain by much more recent Quaternary formations, including Clay-with-Flints (on the Chalk), till and other glacial deposits (mostly in the upper part of the catchment), and fluvial sand, gravel and alluvium (in the lower parts of today's valleys, but also on some higher ground in east Hertfordshire , Middlesex and west Essex , where such deposits were laid down by
7622-487: The marshes known as Wanstead Slip (now in Leyton). The route then continued through Essex to Colchester . At this time, the Lea was a wider river, and the tidal estuary stretched as far as Hackney Wick . Evidence has been found of a late Roman settlement at Old Ford, dating from the 4th and 5th centuries. In 1110, Matilda , wife of Henry I , reputedly took a tumble at the ford, on her way to Barking Abbey and ordered
7725-506: The modern Welsh "Li" pronounced "Lea" which means a flow or a current. Much of the middle Lea were historically known as 'Mereditch', the first element deriving from the Old English ‘gemaera’, meaning boundary. This was due to that section of the river’s role as the dividing line between territories, for instance separating Middlesex and Essex. By the 20th century 'Mereditch' had evolved to 'Mare Dyke' and referred to just one channel of
7828-662: The newly diverted Thames (see further notes below). Further north, the newly formed lower Lea was fed by rivers which, as mentioned above, had flowed directly into the proto-Thames prior to the Anglian glaciation. These rivers - the upper Lea, the Mimram , the Beane , the Rib , the Ash and the Stort - today follow courses which are mostly similar to those of their pre-Anglian predecessors. (Note -
7931-473: The north-west ( Mill Hill ) and to the south-east ( Hampstead Heath ), it has probably existed for the last one million years or more. The Finchley Gap has lower ground to the north-east (the catchment area of the River Lea ), and the south-west (the catchment area of the River Brent ). The North Circular Road (A406) passes over the Gap, from one catchment area to the other. The geological history of
8034-486: The occasional seal . Some boat trippers reported observing on 5 August 2005 a Canada goose being pulled underwater very quickly. The London Wildlife Trust suggested that this was most likely caused by a pike . In 2011, Mike Wells claimed that he saw a "goose go vertically down" in the river. Again a pike or mink was suggested as most likely. Vice Magazine suggested that Wells' story may have been invented to publicise authorities' attempts to evict houseboats from
8137-480: The other than had been possible before. Lea Bridge , the second bridge over the lower Lea was built after 1757, to replace the pre-existing ferry. It connected Clapton to the west, and Leyton and Walthamstow to the east. The Iron Bridge carrying the Barking Road over the river to Canning Town was built in 1810. There are significantly more crossings over the more central Lower Lea , than there are over
8240-421: The pre-glacial "proto-Thames" and its former tributaries). The northern boundary of the Lea catchment area rises to an altitude of almost 180 metres, in hills north-east of Luton. The lowest point of the catchment area is the junction of the Lea with the Thames in east London, at an altitude of barely 5 metres. The relief of the upper part of the Lea catchment is one of gently rolling hills, which are divided by
8343-473: The proto-Thames somewhere around Hoddesdon. Just prior to the arrival of the Anglian ice sheet in the Thames basin, this proto-Mole-Wey river appears to have been flowing over a wide, low-gradient valley floor between Palmers Green and Hoddesdon at what is today an altitude of around 60 metres. When the Anglian ice sheet diverted the Thames southwards, the Mole-Wey was cut off at Richmond. As meltwater from
8446-477: The proto-Thames) have been tentatively estimated to be nearly one million years old, and such deposits have been mapped, at a similar altitude, some 8 km to the north-west near Radlett . There is no certainty that the oldest Dollis Hill Gravel was laid down at exactly the same time as the Gerrards Cross Gravel, but the ages are probably comparable, because, in any given section of the London Basin,
8549-646: The retreating Anglian ice sheet gave birth to the south-flowing lower River Lea, that river cut into and followed the line of the former proto-Mole-Wey, between Hoddesdon and Palmers Green. It flowed into the newly diverted Thames, which at that time was spread over a wide flood plain extending as far north as Islington. The earliest line of the lower River Lea is indicated by what appear on the BGS 1:50,000 map as deposits of "Boyn Hill gravel", notably at Forty Hill , Bush Hill and Palmers Green ( Broomfield Park ). These deposits lie at an altitude of approximately 50 metres, just to
8652-437: The river and its surrounding areas change significantly. Around Hertford, the Lea is joined by a number of major tributaries: the Mimram , Beane , Rib , Ash , and then the Stort . This extra volume of water has created a broad flood plain with sometimes steep hills on either side. The river passes through this valley in several channels, which are a result of both human intervention and natural causes. The increased flow made
8755-404: The river and its surrounding land has been recognised through inclusion in a number of parks and by several planning policy designations. Much of the river lies within the Lee Valley Park . Some of the land surrounding the river has been designated as Metropolitan Green Belt or Metropolitan Open Land in order to prevent further urbanisation. The river contains fish and other wildlife such as
8858-415: The river are known as Bow Creek and the river meets the Thames between Blackwall (on the west side) and Canning Town (on the east). In the Roman era , Old Ford , as the name suggests, was the most downstream crossing point of the River Lea. This was part of a pre-Roman route that followed the modern Oxford Street , Old Street , through Bethnal Green to Old Ford and then across a causeway through
8961-494: The river between Chingford and Enfield . The channel was replaced by parts of the Lee Valley Reservoir Chain in the mid 20th century. The River Lea is the major component in a number of place-names, including Leagrave , the suburb of Luton where the source of the river is located, and of Luton and Leyton : both mean "farmstead on the River Lea" . The spelling Lea predominates west (upstream) of Hertford , but both spellings ( Lea and Lee ) are used from Hertford to
9064-535: The river for burying in Ware, but there is no evidence for this. The extensive level of waterborne trade led the historian John Stow , writing in 1603, to describe the Lea as “this pleasant and useful river”. The riverside has hosted a number of major armaments manufacturers, such as the Waltham Abbey Royal Gunpowder Mills , the Royal Small Arms Factory at Enfield Lock (which is now a housing development known as Enfield Island Village ) and
9167-483: The river has since medieval times had alterations made to make it more navigable for boats between the Thames and eastern Hertfordshire and Essex , known as the Lee Navigation . This stimulated much industry along its banks. The navigable River Stort , the main tributary, joins it at Hoddesdon . While the lower Lea remains somewhat polluted, its upper stretch and tributaries, classified as chalk streams , are
9270-447: The river navigable from Hertford, a situation improved by the creation of the Lee Navigation , a deep canal which begins at Hertford Castle Weir . The Stort, the most important tributary of the Lea, joins a short distance from Hertford at Feildes Weir , and is itself navigable as far upstream as Bishops Stortford . The Hertford East railway line passes along the west side of the Lea's flood plain, from Hertford to Tottenham, improving
9373-452: The south the wider expanse of Greater London includes the floodplain settlements of Enfield Lock , Enfield Highway , Brimsdown , Ponders End , Edmonton , Tottenham , Tottenham Hale , Clapton , Lea Bridge , Leyton , Hackney Wick , Old Ford , Bow , Stratford , West Ham , Bromley-by-Bow , Canning Town and Leamouth . A combination of factors led to the development of the valley as an important industrial area. These included, in
9476-463: The succeeding centuries. In 1766, work also began on the Limehouse Cut to connect the river, at Bromley-by-Bow , with the Thames at Limehouse Basin . The Waterworks River , a part of the tidal Bow Back Rivers , has been widened by 8 metres (26 ft) and canalised to assist with construction of the Olympic Park for the 2012 Summer Olympics . In 2009, Three Mills Lock was installed on
9579-441: The surface across which the Anglian ice sheet flowed and on which it left till and other deposits. A cross-section across the Lea Valley at Enfield shows that the Lea has cut down by as much as 45 metres, over a width of more than six kilometres, since the Anglian glaciation. But why did the River Lea move eastwards? It has been suggested that the River Lea has been "tilted...into its eastern bank" by "a north-south monocline " which
9682-420: The valley of the proto-Mole-Wey at least as far south as the Finchley Gap. Both rivers found their passage blocked. Lakes thus began to rise in front of the ice sheet. Lacustrine deposits laid down in these lakes have been identified. As the water rose, it spilled over lower points along the watersheds of these valleys into adjacent valleys. In particular, rising water from the proto-Thames lake spilled over into
9785-410: The valley of the proto-Mole-Wey north of Uxbridge ; and rising water from the lakes of both rivers spilled over into whatever valley then existed to the east, somewhere just beyond Richmond. The proto-Mole-Way was thus cut off around Richmond, where it joined the diverted Thames. When the ice sheet began to melt, it left behind substantial layers of till and other glacial deposits. In particular, in
9888-528: The valley. An extensive area of open land, built up using rubble from the Blitz , is Hackney Marshes . By contrast, Walthamstow Marshes is retained as a Site of Special Scientific Interest (SSSI). Author Jim Lewis wrote several books, covering many subjects about the area, ranging from industry to sport. 51°41′N 0°01′W / 51.69°N 0.01°W / 51.69; -0.01 River Lea The River Lea ( / ˈ l iː / LEE )
9991-547: The valleys that fan out to the north and north-west from an area between Hertford and Hoddesdon. The lower part of the Lea catchment runs from Hoddesdon southwards to east London, with the flood plain of the River Lea as its central feature. That flood plain has a width which extends to about 7 kilometres in Edmonton . From there, the land rises on either side to an altitude of around 120 metres, to gravel-capped plateaus in Hertfordshire ( Northaw ) and Middlesex ( Southgate ) to
10094-430: The west, and to Essex ( Epping Forest ) in the east. The upper part of the catchment area of the River Lea was formerly a group of valleys whose rivers flowed approximately north–south directly into the River Thames (the "proto-Thames"). Until the Anglian glaciation about 450,000 years ago, the Thames flowed north-eastward past Watford , through what is now the Vale of St Albans, then eastwards towards Chelmsford and
10197-514: The young river passes through the Luton Hoo estate and, six miles from its source, enters Hertfordshire . The river then flows east-south-east through Harpenden , Wheathampstead – once capital of the Catuvellauni tribe – through the narrow green gap between the new towns of Hatfield and Welwyn Garden City , and on to the county town of Hertford . At Hertford the shallow river turns briefly north before turning to head due south, and here
10300-566: Was an ancestor of the River Mole (and/or River Wey). In 1994, D.R. Bridgland proposed that Pebble Gravel (or Stanmore Gravel) which is located on Harrow Weald Common (near Bushey Heath) was deposited by an ancestral Mole-Wey, and that that river was a tributary of the River Thames at a time when the latter river was flowing to the north-west of the Vale of St Albans. This could have been nearly two million years ago. He also suggested that similar gravel, located further north-east near Northaw at
10403-505: Was constructed in 1613 to take clean water to London, from the Lea and its catchment areas in Hertfordshire and bypass the polluting industries that had developed in the Lea's downstream reaches. The artificial channel further reduced the flow to the natural river and by 1767 locks were installed below Hertford Castle Weir on the canalised part of the Lea, now the Lee Navigation with further locks and canalisation taking place during
10506-485: Was established "at least as early as the beginning of Eocene times". Pleistocene isostatic adjustment of the London Basin (with uplift in the west caused by erosion and subsidence in the east caused by accumulation of deposits in the North Sea) may also have played a role. The northern section of the valley, although including several towns ( Luton , Harpenden , Hertford and Ware ), is mainly rural. Below Hertford
10609-493: Was the Anglian glaciation of about 450,000 years ago. The ice sheet which then came down from the north of England (and Scandinavia) covered the greater part of East Anglia and passed over the northern part of the Chiltern Hills. When it reached as far south as Ware it divided into two lobes. One of those lobes advanced up the valley of the proto-Thames, in the Vale of St Albans, as far as Watford. The other lobe advanced up
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