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.
The Lea Valley was formed by glacial melt at the end of the last glacial period circa 10,000BC. The eastern side of the valley, in the area where the present day Chingford Reservoirs are situate, is steep and looks toward Muswell Hill and Alexandra Palace and shows a gradual incline into the Essex uplands.
The northern section of the valley, although including several towns (Luton, Harpenden, Hertford and Ware), is mainly rural. Below Hertford 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 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.