 In a canyon at Zion National Park, Utah, new vegetation against a wall of layered red rock sandstone makes a strikingly beautiful still life composition. The blue streaks in the sandstone are sometimes called rock varnish, or desert varnish. These natural patinas come in various hues and are thought to be caused by a build-up of certain bacteria over eons. Early Native American artists chipped through varnish patinas to create petroglyphs, rock art depicting animals, men, hunt scenes, etc.
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