Yes, we visited it ages ago, I can't believe you managed to drill into the Stones to hide your cache
Caching has taken us to places we'd have never known about or thought of visiting and none of them we've been to so far have been placed in such a way that would cause damage to the surroundings - I don't see what the original poster is concerned about to be honest, if actual damage has been caused by placing a particular cache it should be dealt with, if not lets just crack on caching