Catastrophic flooding changes the course of British history

Sonar images of the Channel floor

A catastrophic megaflood separated Britain from France hundreds of thousands of years ago - <em>News Release</em>

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Imperial College London News Release

Embargo for:
1800 BST / 1300 EST
Wednesday 18 July 2007

A catastrophic megaflood separated Britain from France hundreds of thousands of years ago, changing the course of British history, according to research published in the journal Nature today.

The study, led by Dr Sanjeev Gupta   and Dr Jenny Collier    from Imperial College London, has revealed spectacular images of a huge valley tens of kilometres wide and up to 50 metres deep carved into chalk bedrock on the floor of the English Channel.

A rare glimpse via sonar imaging of the channel seabedUsing high-resolution sonar waves the team captured images of a perfectly preserved submerged world in the channel basin. The maps highlight deep scour marks and landforms which were created by torrents of water rushing over the exposed channel basin.

To the north of the channel basin was a lake which formed in the area now known as the southern North Sea. It was fed by the Rhine and Thames, impounded to the north by glaciers and dammed to the south by the Weald-Artois chalk ridge which spanned the Dover Straits. It is believed that a rise in the lake level eventually led to a breach in the Weald-Artois ridge, carving a massive valley along the English Channel, which was exposed during a glacial period.

At its peak, it is believed that the megaflood could have lasted several months, discharging an estimated one million cubic metres of water per second. This flow was one of the largest recorded megafloods in history and could have occurred 450,000 to 200,000 years ago.

The researchers believe the breach of the ridge, and subsequent flooding, reorganised the river drainages in north-west Europe by re-routing the combined Rhine-Thames River through the English Channel to form the Channel River.

The breach and permanent separation of the UK also affected patterns of early human occupation in Britain. Researchers speculate that the flooding induced changes in topography creating barriers to migration which led to a complete absence of humans in Britain 100,000 years ago.

Dr Sanjeev Gupta, from the Department of Earth Science & Engineering at Imperial said: “This prehistoric event rewrites the history of how the UK became an island and may explain why early human occupation of Britain came to an abrupt halt for almost 120 thousand years.”

Project collaborator, Dr Jenny Collier, also from the Department of Earth Science & Engineering, speculates on the potential for future discoveries on the continental shelves.

“The preservation of the landscape on the floor of the English Channel, which is now 30-50 m below sea-level, is far better than anyone would have expected. It opens the way to discover a host of processes that shaped the development of north-west Europe during the past million years or so,” said Dr Collier.

The Imperial research team collaborated with the UK Hydrographic Office and the Maritime Coastguard Agency (MCA) on the project. Data collected by the MCA and archived by the Hydrographic Office was originally sourced for civil safety at sea.


For further information please contact:

Colin Smith
Press Officer
Imperial College London
Tel: +44 (0)207 594 6712
Out of hours duty press officer: +44 (0)7803 886 248

Note to editors:

1. Catastrophic flooding origin of shelf valley systems in the English Channel" Journal of Nature, 19 July 2007. Available on request from Helen Jamison, Nature’s Press Officer, on +44 (0)20 7843 4658.

The full listing of authors and their affiliations for the Nature paper is as follows: Sanjeev Gupta(1), Jenny S. Collier(1), Andy Palmer-Felgate(1) & Graeme Potter(2). 1 Department of Earth Science and Engineering, Imperial College London, London SW7 2AZ, UK. 2 UK Hydrographic Office, Admiralty Way, Taunton, Somerset TA1 2DN, UK.

2. About the United Kingdom Hydrographic Office

Based in Taunton, Somerset the UK Hydrographic Office (UKHO) is a self-funding Government Agency with Trading Fund status.
The UK Hydrographic Office is the owner of the Admiralty brand, a name globally renowned for its world series of safety-critical navigational charts and publications. British Admiralty has protected the lives of millions of mariners both in our Royal Navy and in worldwide shipping since 1795. Today, these paper products command more than 65% of the world market share.
The UKHO currently provides wide coverage with electronic charts via the Admiralty brand. It has developed the award-winning Admiralty TotalTide worldwide digital tidal information and has recently won a Seatrade Award for The Admiralty Digital List of Lights.

3. About the Maritime and Coastguard Agency

This Maritime and Coastguard Agency is responsible throughout the UK for implementing the Government's maritime safety policy. That includes co-ordinating search and rescue at sea through Her Majesty's Coastguard, and checking that ships meet UK and international safety rules. We work to prevent the loss of lives at the coast and at sea, to ensure that ships are safe, and to prevent coastal pollution. Safer Lives, Safer Ships, Cleaner Seas

4. About Imperial College London

Rated as the world's ninth best university in the 2006 Times Higher Education Supplement University Rankings, Imperial College London is a science-based institution with a reputation for excellence in teaching and research that attracts 11,500 students and 6,000 staff of the highest international quality.
Innovative research at the College explores the interface between science, medicine, engineering and management and delivers practical solutions that improve quality of life and the environment - underpinned by a dynamic enterprise culture.

With 66 Fellows of the Royal Society among our current academic staff and distinguished past members of the College including 14 Nobel Laureates and two Fields Medallists, Imperial's contribution to society has been immense.

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The College's 100 years of living science will be celebrated throughout 2007 with a range of events to mark the Centenary of the signing of Imperial's founding charter on 8 July 1907.


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