What struck me was the absence, how it stretched out in all directions. Indistinguishable. The trees were stunted and small, scraggly things, as flimsy as old paper dried up and twisted and left to the dust of the endless desert landscape. From the ridge, they spotted the ravine's slope here and there all the way down to where it met the empty, mud-cracked stream bed. Out here, they called that a river. They had the nerve to mark it on a map. When I looked down into the ravine from the top of the ridge where I was standing, a sense of vertigo swept through me. The unfamiliar shrunken size of the trees tricked the eye, so that even shrubs which I knew were only a few feet down seemed to stretch the landscape into an odd but persistent sensation of distance. A gradual slope dropped away in an optical illusion of dizzying depth. I blinked. I thought, this was what the Discworld Witches called "gnarly ground."