Artist Kurt Wenner is known for brain-defying creations. He makes drawings on pavement that feel 3D, often from the perspective of looking down into a scene struggle or chaos. Wenner recently took on a topic central to the Western United States: the Colorado River. He recreated the river's winding path... across the marble floor of Chicago’s Union Station. It’s part of an environmental campaign by an almond and soymilk manufacturer. Aspen Public Radio’s Elise Thatcher talks with Kurt Wenner, from his home in Washington State…. and it turns out he’s got a trick for keeping his artwork durable.