Home‎ > ‎G) Personal Projects‎ > ‎G.N) Lidar Imagery‎ > ‎

G.N.1) Mystery Circles

With a view to 3D printing some terrain, I created a Lidar view of Petworth in Sussex.

[1m DTM data, image is hillshaded and unsmoothed]

Reasonably interesting in its own right, but to the north-east I spotted some interesting circular artefacts, as below. These are in dense woodland that used to be one of my stomping-grounds as a child. The 'pock-marking' to the north-east is (I believe) quarrying for local sandstone.

[1m DTM data, image is hillshaded and unsmoothed]

The big 'crater' in the northernmost circle is about three meters deep and, I believe, another ex quarry.

The historical context includes this area being the only route into Petworth from the East until the construction of Horsham Road. Once dense woodland of Oak and Beech, this area was devastated by the "hurricane" of 1987 and is now largely birch. Chestnut is coppiced nearby.

Overlaying an OS Map showed an apparent 'clearing' in the woodland that aligned with one of the circles. Chemicals in the soil? Insufficient depth of soil? Trees cut down intentionally? Did their use require natural daylight?

[(c) Ordnance Survey]

Remarkably, the cutting of a swathe through the woodland the 1970s to allow electricity cables to be routed (the long empty rectangular feature running northwest) seems not to have disturbed these ground features.

They are included in a map from 1875:

(Note that the feature next to Goanah Lodges is shown as a mound rather than a "ridge").

They also appear on an OS map from 1898:

Though it doesn't show up very well in the image, one of the smaller ones is visible as a distinct ridge in an almost perfect circle. The ground inside is at the same height as that outside.

The girth of the yew trees in this picture suggests an age of circa 150 yrs. I couldn't measure the girth of the nearby tree.

The Forestry Commission's Gazetteer of Archaeological Features found in Woodlands comments:

"Low (less than 0.25 metres high), and wide (between 2 and 3 metres) rounded banks may also be found in woodland, especially ancient woods. It is not clear what their origin may be – former coppice divisions perhaps, or former ancient field boundaries".

The Answer:
I asked James Kenny, Archaeology Officer at Chichester District Council: he solved the case and considers them to be the remains of boundaries that would have been used to prevent grazing animals from gaining access to newly-planted plantations. What his expert eye spotted that mine did not is that in the 1875 the trees inside the circles are shown with a ‘coniferous tree’ symbol and the surrounding area is open heath. As these features weren't listed in the 1838 Petworth tithe map they must have been planted later than 1838; to be mature conifers in 1875 suggests the trees must have been planted in about 1850. This also explains the 'clearing' - the conifers inside the circle had been felled.

Such arboreal features would be one Victorian means of showing-off. These trees would be visible from Petworth Park, from Barton's Lane when leaving Petworth to go east and when approaching Gohana Lodges to reach Petworth from the east.

Similar plantings still exist to the west of these no-longer-a-mystery circles.

So, no treasure, no items of great value or evidence of alien visitations but interesting none-the-less.