Slot canyons are natural fissures in snadstone rock that start as a narrow slot at the top and open up inside to reveal fantastic sculpted shapes where udeground rivers have viciously carved a path through the rocks over the centuries by water erosion. These are some of the most beautiful natural art structures in the world and they come to life when shafts of direct sandstone bounce ever softer light off the red walls of the cliffs illuminating all with a firey glow.