The curved to irregular bands seen in these pictures are deposits of iron minerals and are called Liesegang bands. These bands are reddish-brown to yellow in color and are common in cliff-forming sandstones, such as those in the Red River Gorge, Cumberland Falls, Natural Bridge and Cumberland Gap areas. Much of the red iron mineralization in these bands are hematite, goethite and limonite. The source of the iron is the carbonate mineral siderite. But when siderite weathers, it oxidizes forming the yellow-brown mineral limonite as well as hematite and goethite.