Far down the track from Stonehenge and past Normanton Down, as you approach the Lake Group, the path climbs up a hill. About half way up, leading up the edge of the Lake Group wood, an earthwork is marked on the map. No longer a ditch or bank, a strong cropmark jumps out at you. I've seen pictures of cropmarks in ariel photographs, but have been disappointed on the ground. Not here.
The cropmark is only visible on the eastern side, where grass is growing, becoming thick and lush on the site of the earthwork. A different crop is growing on the western side, and the site of the earthwork isn't visible at all, not when we visited.
Not the most imposing of sites, but certainly worth the walk if you're in the area (but the walk itself is certainly worth it), just to see what this cropmark business is all about, without the use of a plane ...
The reason this Bronze Age earthwork survives as well as it does is mostly due to it still acting as a boundary between two fields and so has not suffered the plough. A lot of the linear archaeology in the Stonehenge area was flattened by mediaeval ploughing but this well-preserved section of boundary bank and ditch across Wilsford Down has survived and is clearly visible within the modern landscape, both from the ground and the air.
See the detail from the 1810 map of the area by Colt-Hoare for a clearer idea of how this feature fitted into the barrow groups in the area.
Another bank, only intermittently preserved, runs north-westwards from the wood in the Lake barrow group, up to the Winterbourne Stoke barrow group at the junction of Longbarrow Crossroads with the A303. This may have originally been created as a boundary between the two massive Long barrows, each being the centre of the barrow grouping.