literaly. doesnt matter what type of stone it is, it will fall off where it is, unless you have a "border" to keep it where ever you put it (if you see what i am trying to say)
other thing is it moves. my garden has a slight slope from left to right, although its only walked on, a couple of times a year i shovel it from the bottom of the slope back up again.
Breezer,
Our drive actually slopes upward at the bottom (or entrance which ever way you want to look at it). My wife and I really like the clean look it gives the property in which it sits (Cotswold stone I mean)