The monument includes Tarr Steps, a 55m long multi-span stone clapper bridge which crosses the River Barle; it is believed to be of medieval date and is Listed Grade I.
The Barle rises about 17km to the north west of the clapper bridge and cuts through a deep wooded valley between Simonsbath and Dulverton. The bridge is located adjacent to a ford on the single track road which connects the villages of Hawkridge and Winsford. It is constructed from rectangular rough-grit sandstone slabs, obtained locally from the Pickwell Down basement beds, with 17 spans set on stone piers which are raised about 1m above the river bed. Twelve of the horizontal spanning stones are single; four are in pairs and one, which forms the end span on the eastern side, has three parallel stones. The stones are between 2m to 2.9m long, 2m to 1.6m wide and up to 0.3m thick and are supported by piers which are constructed of dry-stone blocks laid one upon another and set at about 2m intervals. The average size of the supporting blocks is 2.2m long, 0.7m wide and 0.7m thick. Each of the piers have up to three stone slabs laid against them on either side. These appear to act as cutwaters on the upstream side in order to protect the piers from flood damage and as supports for the bridge on the downstream side.
Perhaps because of its megalithic character and its proximity to trackways which are thought to be of Bronze Age date, Tarr Steps has commonly been believed to date from the prehistoric period. However, recent research has suggested that it is more likely to be medieval. It is known from documentary sources that in 1279 the River Barle was crossed by a bridge at Three Waters, located less than 2km to the south. This suggests Tarr Steps was not constructed until after 1279 as it would seem unlikely that two bridges crossing the same river would have co-existed in such close proximity. Research into similarly constructed clapper bridges on Dartmoor suggest that they were unlikely to date from before about 1400.
The modern surfacing of the road on the north side of the bridge is excluded from the scheduling, although the ground beneath it is included.
Book Reference - Title: National Monument Record - Type: DESC TEXT - Description: SS 83 SE 1
Book Reference - Author: Grinsell, L V - Title: The Archaeology of Exmoor - Date: 1970 - Page References: 148-150 - Type: DESC TEXT - Description: Communications
Book Reference - Author: Jervoise, E - Title: The Ancient Bridges of S England - Date: 1930 - Page References: 112 - Type: DESC TEXT - Description: The Bridges of Exmoor