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Conversion of marshland[edit]
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 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 name Lower Marsh preserves a memory.[34]
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; the River Lea can be considered another boundary.[35] 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 km2, 7.12 sq mi; population 40,000[36]) was once marshy, but is now a fully reclaimed island in the Thames estuary, separated from the mainland of south Essex by a network of creeks. Lying below sea level, it is prone to flooding at exceptional tides, but has nevertheless been inhabited since Roman times.
Wildlife[edit]
Swan Upping – skiffs surround the swans
Fishing at Penton Hook Island
Various species of birds feed off the river or nest on it, some being found both at sea and inland. These include cormorant, black-headed gull and herring gull. The mute swan is a familiar sight on the river but the escaped black swan is more rare. The annual ceremony of Swan Upping is an old tradition of counting stocks.
Non-native geese that can be seen include Canada geese, Egyptian geese and bar-headed geese, and ducks include the familiar native mallard, plus introduced Mandarin duck and wood duck. Other water birds to be found on the Thames include the great crested grebe, coot, moorhen, heron and kingfisher. Many types of British birds also live alongside the river, although they are not specific to the river habitat.
The Thames contains both sea water and fresh water, thus providing support for seawater and freshwater fish. However, many populations of fish are at risk and are being killed in tens of thousands because of pollutants leaking into the river from human activities.[37] Salmon, which inhabit both environments, have been reintroduced and a succession of fish ladders have been built into weirs to enable them to travel upstream.
On 5 August 1993, the largest non-tidal salmon in recorded history was caught close to Boulters Lock in Maidenhead. The specimen weighed 14+1⁄2 lb (6.6 kg) and measured 22 in (56 cm) in length. The eel is particularly associated with the Thames and there were formerly many eel traps. Freshwater fish of the Thames and its tributaries include brown trout, chub, dace, roach, barbel, perch, pike, bleak and flounder. Colonies of short-snouted seahorses have also recently been discovered in the river.[38] The Thames is also host to some invasive crustaceans, including the signal crayfish and the Chinese mitten crab.
Aquatic mammals are also known to inhabit the Thames. The population of grey and harbour seals numbers up to 700 in the Thames Estuary. These animals have been sighted as far upriver as Richmond.[39] Bottlenose dolphins and harbour porpoises are also sighted in the Thames.[40]
On 20 January 2006, a 16–18 ft (4.9–5.5 m) northern bottle-nosed whale was seen in the Thames as far upstream as Chelsea. This was extremely unusual: this whale is generally found in deep sea waters. Crowds gathered along the riverbanks to witness the spectacle but there was soon concern, as the animal came within yards of the banks, almost beaching, and crashed into an empty boat causing slight bleeding. About 12 hours later, the whale is believed to have been seen again near Greenwich, possibly heading back to sea. A rescue attempt lasted several hours, but the whale died on a barge. See River Thames whale.[41]
Human history[edit]
The Tower of London begun in the 11th century, with Tower Bridge, built 800 years later
The River Thames has played several roles in human history: as an economic resource, a maritime route, a boundary, a fresh water source, a source of food and more recently a leisure facility. In 1929, John Burns, one-time MP for Battersea, responded to an American's unfavourable comparison of the Thames with the Mississippi by coining the expression "The Thames is liquid history".
There is evidence of human habitation living off the river along its length dating back to Neolithic times.[42] The British Museum has a decorated bowl (3300–2700 BC), found in the river at Hedsor, Buckinghamshire, and a considerable amount of material was discovered during the excavations of Dorney Lake.[43] A number of Bronze Age sites and artefacts have been discovered along the banks of the river including settlements at Lechlade, Cookham and Sunbury-on-Thames.[44]
So extensive have the changes to this landscape been that what little evidence there is of man's presence before the ice came has inevitably shown signs of transportation here by water and reveals nothing specifically local. Likewise, later evidence of occupation, even since the arrival of the Romans, may lie next to the original banks of the Brent but have been buried under centuries of silt.[44]
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