“The best of authorities, all are agreed
The source of the Thames is in Trewsbury Mead!”
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1. As the source of the River Thames, what would you expect to see here?
2. Describe what you see at the time of your visit. Is water flowing? Is the current strong or weak? What is the approximate depth and width of the river?
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River Thames
The official source of the River Thames is this spring in a field north of the Gloucestershire village of Kemble. There is no doubt that the water bubbling up to the surface from this underground spring does start the river on its journey to the sea, but the spring is seasonal, and you will only see water here during a wet winter or after heavy rain. In very dry periods you won't see any water in the river course for several miles further south, but at most times of the year you will see water flowing between the spring and the village of Kemble.
The River Thames flows through southern England including London. It’s fed by at least 50 named tributaries. 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.
It flows through Oxford (where it is commonly called the Isis), Reading, Henley-on-Thames and Windsor. The lower reaches of the river are called the Tideway, derived from its long tidal reach up to Teddington Lock. The Thames drains the whole of Greater London and flows into the North Sea via the Thames Estuary.
Geological History
Researchers have identified the River Thames as a discrete drainage line flowing as early as 58 million years ago. 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.
About 450,000 years ago, during the most extreme Ice Age of the Pleistocene, 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 the river to divert onto its present course through the area of present-day London. The ice lobe, which stopped at present-day Finchley deposited about 14 metres of boulder clay there. Its torrent of meltwater gushed through the Finchley Gap and south towards the new course of the Thames, and proceeded to carve out the Brent Valley in the process.
