Hi Rhiannon
< But I suppose it's not always near water so that's that one dismissed? >
Bittova sweep there! I didn't mean to infer that all cup&rings are water-based. Apologies if I meant to give that impression. Merely that it seems highly probable that quite a few carvings had some mythic relationship with it. As well as with light. And, in some cases, them there entoptics aswell...
If there's one thing I've learnt thru the years, it's that there's no one singular answer to these damn things!