ETCHILHAMPTON AUG 06
Analysis using almost vertical photo shot, unadjusted. Some distortion is obvious but maybe due to photo angle or ground slope.
Obvious link to the earlier Blowingstone Hill, Kingston Lisle formation. My earlier analysis was based on a low angle photo, adjusted in Photoshop, which was inaccurate. The formation appears to be well constructed with no obvious inaccuracies.
The four main curves of the star are parabolae, formed naturally and therefore unremarkably from the envelope of the 'sliding ladder' sequence of lines, which are all of the same length. The 4 pointed star formation is called an 'Astroid' in geometry. It is a standard geometric construction. See this link for example.
The inner blue circle which is laid in the formation has an approximate relation to the outer circle as a 10 pointed star. (Using the Hawkins' theorem of tangents) This may be coincidence. However there are 10 straight lines on each axis.
I see no further geometric subtleties or hidden references in this formation, therefore my conclusion based on geometric analysis alone is that is is man-made.
The curve is a parabola.