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Archaeologists dig up rare medieval waterwheel

16 February 2009
By Mike Brooke

ARCHAEOLOGISTS have uncovered a rare medieval tidal mill on the River Thames.

The discovery was made at Limehouse Reach in East London, where a team has been excavating peat soil on the foreshore at Greenwich Wharf, opposite the area known as Millwall on the Isle of Dogs.

It is remarkably well preserved in riverside peat deposits, archaeological experts from the Museum of London revealed today.

They believe it is the foundations of London’s earliest-found medieval tide-powered mill.

The huge structure, measuring 30ft by 36ft at its base, would have had a wheel diameter of 16ft, an incredible size for a wooden structure of this type which represents an extraordinary example of medieval engineering, dated to the 12th century. Analysis of tree rings has dated the trees used for its construction to 1194.

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Tidal Mills worked by drawing in water from the river as the tide rose and releasing it as it fell.

The mill at Limehouse Reach features a substantial fragment of intact waterwheel and an enormous trough to channel the water which was shaped out of a single oak beam. The medieval carpenters’ construction marks are still clearly visible.

It was discovered during archaeological investigations by the museum’s team working with contractors getting the land ready for a new residential development at Greenwich Wharf.

Four mills in Greenwich are mentioned in the Doomsday Book in 1086.

The remains of the structure have been dismantled, with each timber carefully recorded so it can be properly researched. Sections of the find which have been removed, including the trough and waterwheel, are now undergoing conservation treatment to preserve them from 21st century air pollution.