"Very, very carefully. As carefully as humanly possible," he said, easing back slowly and keeping the bulk of his attention on the ground underneath their feet. "There seems to be a rather distressing tendency of the rock in this area to give way into a chasm just like the one you found. It is the one you found, actually. I really don't fancy trying to make our way out of it hanging by our fingertips, so try to step very, very softly."