http://www.stonehenge-avebury.net/Photos/gtour/Minchin.jpg
That's a big bugger!
Haven't been to Minchinhampton in many years, but the common had a GPS survey done in 2000 by English Heritage, Severn trent dug some of it up for waterworks improvements, and I think a preliminary archeo dig was carried out. Maybe English heritage could help??Ah, i just looked: here
"Minchinhampton Common is remarkable for the density and timespan of the archaeological remains surviving as earthworks. These range from a Neolithic tomb, through prehistoric fields and post-medieval 'pillow mounds' (artificial rabbit warrens), to Second World War anti-glider trenches (long ditches dug to ensure that enemy gliders would crash on landing). Some of these earthworks are extremely slight, and nothing is straightforward, because the area has seen so many episodes of use and re-use. For example, the nature and date of the massive apparently defensive earthworks known as the 'Bulwarks' remains uncertain. Amberley Camps, supposedly a prehistoric fortification, is almost certainly nothing more than a pattern of medieval woodland boundaries. And then there are hundreds of small hollows associated with slight mounds of upcast – surface quarries or holes left by the roots of trees blown over in the Great Storm of 1703?"