The amazing concave shape of Malham and the overhang meant that when we stood below the climbers at the bottom of Malham Cove, we could hear a lot of what's being said. It's not perfect. There will be no clear focal point. So we would say that as a mirror for sound it suffers from spherical aberration. It would have needed to be parabolic to work perfectly and I don't think melt water from glaciers does that to order.
