Burnard describes this photograph as "section of Great Central Trackway in Webbs Marsh, Postbridge".
Crossing on page 32 of his 'Guide to Dartmoor' provides a trenchant argument that this apparent trackway is actually a reave. Reaves are banks of earth and stone that often run across the moor for many miles. They are considered to have been constructed during the Bronze Age (1500 - 800 BC) as boundary markers.
The reave/trackway of which Burnard shows a section, runs from the north-west of Postbridge to Lower White Tor and is described on the Ordnance Survey map as a 'Boundary Work'.