This is a tall HooDoo from down here! Persistent, dry winds blow away the many layers of soil from the tops and sides of hills and coulees, meanwhile the snow and ice break up the formations, with the runoff pulling the sand and slowly eroding away the layers of rock. Many badlands have been formed in this exact manner, but hoodoos carry something stronger that sets them apart. Atop each and every hoodoo is a stronger, harder rock that disallows erosion from above. The rain and wind swept sand cannot erode the hard iron caps each hoodoo wears, and so must erode the sandstone below. Slightly acidic rainwater further eats into and rounds off the sandstone hoodoo towers. Eventually the sandstone will fail, and the harder, stronger tops will fall.