Our chicken run floor is made up of a foot of sand and gravel, topped by a few inches of wood chips. There isn't any dirt for them to have a nice dust bath in. Dust bath? Apparently dust is good for their feathers, and helps reduce mites. When we let them out, the chickens often spend a lot of time next to Matt and Marissa's house where there is a nice patch of loose, dry dirt. I enjoyed watching them have some "spa time."