I hear what you're saying Tom.

I've just noticed this shot, which is a bit more alarming than the ones I saw earlier:

http://www.themodernantiquarian.com/post/18056

There's what looks like chalk in the cup marks. This would mean that a horizontal traverse is being used with the crack near the floor, presumably being used for footholds. If that's the case, the constant rubbing of shoes against the rock surface as the climbers try to get a footing could do harm. The soles can often leave behind bits of rubber on the surface too.

Another thing I've just realised/remembered, and probably more of a threat, is climbers often carry round really tough, stubby little wire brushes to clean up finger holds and foot holds - gods forbid that they get one of those things near the carvings!

Definitely needs a sign putting up.

>If the books do mention the carvings and stress that they shouldn't be climbed on then that too is probably enough for most climbers.

Definitely - if there's no route detailed it won't get climbed (apart from by the odd idiot, but again, what can you do). The sport is about achieving set routes - that's where the competitive element lies. If it's no longer a recognised bit of bouldering, I don't reckon anyone would bother with it. Especially considering the stupendous amount of top class climbing available within 10-15 minutes!