Walderslade Woods 1
Image by slumpystones
Walderslade Woods

F.A.O. Slumpy .

First impressions would lead me to suspect that this photo
http://smg.photobucket.com/albums/v239/slumpy_uk/walderslade%20woods/?action=view¤t=moto_0042.jpg
may possibly give a clue to the origin of the ring and indicate weathering as opposed to carving as the cause

cheers fitz

fitzcoraldo wrote:
First impressions would lead me to suspect that this photo
http://smg.photobucket.com/albums/v239/slumpy_uk/walderslade%20woods/?action=view¤t=moto_0042.jpg
may possibly give a clue to the origin of the ring and indicate weathering as opposed to carving as the cause

cheers fitz

Precisely the reason I included it! It looks like successive bouts of water/pebble erosion has taken place, leaving a stepped cone.

However, the main ring certainly doesn't look like that, and although it does use existing cracks or grooves in the stone, I can't see how it would possibly have been done naturally.