In reply to Stig: Recently had problems with a bunch of ramblers (you know, the flask of tea, gaiters, map and compass but never leave the F**KING ROAD!!!!!!) having a go at me for loading loads of bits of rock into my car giving me the old "take nothing but photos, leave nothing but footprints" and "well if everyone took a few rocks then there would be none left...."
Just wanna save others from the ear ache I got listening to Harold, Hilda and the sunshine club.
The only problem I have had with using rock is that it spins really easily. The bolts chew the rock fairly easily.
The way I solved it was using rubber washers between the bolt head and the surface of the rock. Works a treat.
Hope the wall is going well Stig.