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Clapper Bridge
Tarr Steps, Exmoor, Somerset, England
Ancestor	Step-stone bridge
Related	Log bridge
Descendant	Arch bridge, trestle
Carries	Pedestrians
Span range	Short
Material	Stone
Movable	No
Design effort	Low
Falsework required	No

A clapper bridge is an ancient form of bridge found on the moors of Devon (Dartmoor and Exmoor) and in other upland areas of the United Kingdom including Snowdonia and Anglesey. It is formed by large flat slabs of granite or schist supported on stone piers (across rivers), or resting on the banks of streams. According to the Dartmoor National Park, the word 'clapper' derives from an Anglo-Saxon word, 'cleaca', meaning 'bridging the stepping stones'.

Although often believed to be of prehistoric origin, most were erected in medieval times, and some in later centuries. They are often situated close to a ford where carts could cross.

The largest clapper bridge, Anping bridge[1], was built at around 1000 AD in Fujian Province, China. The bridge is 2223 meters long, and the largest granite slab span is 2.5 feet deep and wide and 35 feet long estimated to weigh 20 tons[2].

Another fine example is to be found at Postbridge, on Dartmoor. Its slabs are over four metres (13ft) long, two metres (6ft 6in) wide and weigh over eight tons each, making the bridge passable to a small cart. It was first recorded in 1380 and was built to facilitate the transportation of tin by pack horses to the stannary town of Tavistock.

Surviving examples include the Tarr Steps over the River Barle in Exmoor.

Other larger clapper bridges, such as at Dartmeet and Bellever, have collapsed - their slabs swept away by floods, or raided for building or wall construction. However, there are many other smaller examples in existence on Dartmoor and still in use, such as those at Teignhead Farm (close to Grey Wethers stone circles), Scorhill and across the Wallabrook stream.

Small clapper bridge over Afon Cadnant, near Menai Bridge, Anglesey (the hand-rail is a modern addition).