Clapper bridge

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, Cumbria, Yorkshire and Lancashire. It is formed by large flat slabs of stone, often granite or schist, supported on stone piers (across rivers), or resting on the banks of streams.

Although often credited with 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. According to the Dartmoor National Park, the word 'clapper' derives ultimately from an Anglo-Saxon word, cleaca, meaning 'bridging the stepping stones' the Oxford English Dictionary gives the intermediate Medieval Latin form clapus, claperius, "of Gaulish origin", with an initial meaning of "a pile of stones".

A fine example, the Postbridge Clapper Bridge (illustration, left), can be found at Postbridge, on Dartmoor. Its slabs are over four metres (13 ft) long, two metres (6 ft 6 in) 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 Dartmoor tin by pack horses to the stannary town of .

Other surviving examples include the Tarr Steps over the River Barle in Exmoor, and Stara Bridge over the River Lynher in east Cornwall.